library.js

//"use strict";

// An implementation of a libc for the web. Basically, implementations of
// the various standard C libraries, that can be called from compiled code,
// and work using the actual JavaScript environment.
//
// We search the Library object when there is an external function. If the
// entry in the Library is a function, we insert it. If it is a string, we
// do another lookup in the library (a simple way to write a function once,
// if it can be called by different names). We also allow dependencies,
// using __deps. Initialization code to be run after allocating all
// global constants can be defined by __postset.
//
// Note that the full function name will be '_' + the name in the Library
// object. For convenience, the short name appears here. Note that if you add a
// new function with an '_', it will not be found.

// Memory allocated during startup, in postsets, should only be ALLOC_STATIC

LibraryManager.library = {
  // keep this low in memory, because we flatten arrays with them in them
  stdin: 'allocate(1, "i32*", ALLOC_STATIC)',
  stdout: 'allocate(1, "i32*", ALLOC_STATIC)',
  stderr: 'allocate(1, "i32*", ALLOC_STATIC)',
  _impure_ptr: 'allocate(1, "i32*", ALLOC_STATIC)',
  __dso_handle: 'allocate(1, "i32*", ALLOC_STATIC)',
  $PROCINFO: {
    // permissions
    /*
    uid: 0,
    gid: 0,
    euid: 0,
    egid: 0,
    suid: 0,
    sgid: 0,
    fsuid: 0,
    fsgid: 0,
    */
    // process identification
    ppid: 1,
    pid: 42,
    sid: 42,
    pgid: 42
  },

  // ==========================================================================
  // dirent.h
  // ==========================================================================

  opendir__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'open'],
  opendir: function(dirname) {
    // DIR *opendir(const char *dirname);
    // http://pubs.opengroup.org/onlinepubs/007908799/xsh/opendir.html
    // NOTE: Calculating absolute path redundantly since we need to associate it
    //       with the opened stream.
    var path = Pointer_stringify(dirname);
    if (!path) {
      ___setErrNo(ERRNO_CODES.ENOENT);
      return 0;
    }
    var node;
    try {
      var lookup = FS.lookupPath(path, { follow: true });
      node = lookup.node;
    } catch (e) {
      FS.handleFSError(e);
      return 0;
    }
    if (!FS.isDir(node.mode)) {
      ___setErrNo(ERRNO_CODES.ENOTDIR);
      return 0;
    }
    var fd = _open(dirname, {{{ cDefine('O_RDONLY') }}}, allocate([0, 0, 0, 0], 'i32', ALLOC_STACK));
    return fd === -1 ? 0 : FS.getPtrForStream(FS.getStream(fd));
  },
  closedir__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'close', 'fileno'],
  closedir: function(dirp) {
    // int closedir(DIR *dirp);
    // http://pubs.opengroup.org/onlinepubs/007908799/xsh/closedir.html
    var fd = _fileno(dirp);
    var stream = FS.getStream(fd);
    if (stream.currReading) stream.currReading = null;
    return _close(fd);
  },
  telldir__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  telldir: function(dirp) {
    // long int telldir(DIR *dirp);
    // http://pubs.opengroup.org/onlinepubs/007908799/xsh/telldir.html
    var stream = FS.getStreamFromPtr(dirp);
    if (!stream || !FS.isDir(stream.node.mode)) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    return stream.position;
  },
  seekdir__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'lseek', 'fileno'],
  seekdir: function(dirp, loc) {
    // void seekdir(DIR *dirp, long int loc);
    // http://pubs.opengroup.org/onlinepubs/007908799/xsh/seekdir.html
    var fd = _fileno(dirp);
    _lseek(fd, loc, {{{ cDefine('SEEK_SET') }}});
  },
  rewinddir__deps: ['seekdir'],
  rewinddir: function(dirp) {
    // void rewinddir(DIR *dirp);
    // http://pubs.opengroup.org/onlinepubs/007908799/xsh/rewinddir.html
    _seekdir(dirp, 0);
    var stream = FS.getStreamFromPtr(dirp);
    if (stream.currReading) stream.currReading = null;
  },
  readdir_r__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  readdir_r: function(dirp, entry, result) {
    // int readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result);
    // http://pubs.opengroup.org/onlinepubs/007908799/xsh/readdir_r.html
    var stream = FS.getStreamFromPtr(dirp);
    if (!stream) {
      return ___setErrNo(ERRNO_CODES.EBADF);
    }
    if (!stream.currReading) {
      try {
        // load the list of entries now, then readdir will traverse that list, to ignore changes to files
        stream.currReading = FS.readdir(stream.path);
      } catch (e) {
        return FS.handleFSError(e);
      }
    }
    if (stream.position < 0 || stream.position >= stream.currReading.length) {
      {{{ makeSetValue('result', '0', '0', 'i8*') }}};
      return 0;
    }
    var id;
    var type;
    var name = stream.currReading[stream.position++];
    if (!name.indexOf('.')) {
      id = 1;
      type = 4;
    } else {
      try {
        // child may have been removed since we started to read this directory
        var child = FS.lookupNode(stream.node, name);
      } catch (e) {
        // skip to the next entry (not infinite since position is incremented until currReading.length)
        return _readdir_r(dirp, entry, result);
      }
      id = child.id;
      type = FS.isChrdev(child.mode) ? 2 :  // DT_CHR, character device.
             FS.isDir(child.mode) ? 4 :     // DT_DIR, directory.
             FS.isLink(child.mode) ? 10 :   // DT_LNK, symbolic link.
             8;                             // DT_REG, regular file.
    }
    {{{ makeSetValue('entry', C_STRUCTS.dirent.d_ino, 'id', 'i32') }}};
    {{{ makeSetValue('entry', C_STRUCTS.dirent.d_off, 'stream.position', 'i32') }}};
    {{{ makeSetValue('entry', C_STRUCTS.dirent.d_reclen, C_STRUCTS.dirent.__size__, 'i32') }}};
    for (var i = 0; i < name.length; i++) {
      {{{ makeSetValue('entry + ' + C_STRUCTS.dirent.d_name, 'i', 'name.charCodeAt(i)', 'i8') }}};
    }
    {{{ makeSetValue('entry + ' + C_STRUCTS.dirent.d_name, 'i', '0', 'i8') }}};
    {{{ makeSetValue('entry', C_STRUCTS.dirent.d_type, 'type', 'i8') }}};
    {{{ makeSetValue('result', '0', 'entry', 'i8*') }}};
    return 0;
  },
  readdir__deps: ['readdir_r', '__setErrNo', '$ERRNO_CODES'],
  readdir: function(dirp) {
    // struct dirent *readdir(DIR *dirp);
    // http://pubs.opengroup.org/onlinepubs/007908799/xsh/readdir_r.html
    var stream = FS.getStreamFromPtr(dirp);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return 0;
    }
    // TODO Is it supposed to be safe to execute multiple readdirs?
    if (!_readdir.entry) _readdir.entry = _malloc({{{ C_STRUCTS.dirent.__size__ }}});
    if (!_readdir.result) _readdir.result = _malloc(4);
    var err = _readdir_r(dirp, _readdir.entry, _readdir.result);
    if (err) {
      ___setErrNo(err);
      return 0;
    }
    return {{{ makeGetValue(0, '_readdir.result', 'i8*') }}};
  },

  // ==========================================================================
  // utime.h
  // ==========================================================================

  utime__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  utime: function(path, times) {
    // int utime(const char *path, const struct utimbuf *times);
    // http://pubs.opengroup.org/onlinepubs/009695399/basedefs/utime.h.html
    var time;
    if (times) {
      // NOTE: We don't keep track of access timestamps.
      var offset = {{{ C_STRUCTS.utimbuf.modtime }}};
      time = {{{ makeGetValue('times', 'offset', 'i32') }}};
      time *= 1000;
    } else {
      time = Date.now();
    }
    path = Pointer_stringify(path);
    try {
      FS.utime(path, time, time);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  utimes__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  utimes: function(path, times) {
    var time;
    if (times) {
      var offset = {{{ C_STRUCTS.timeval.__size__ }}} + {{{ C_STRUCTS.timeval.tv_sec }}};
      time = {{{ makeGetValue('times', 'offset', 'i32') }}} * 1000;
      offset = {{{ C_STRUCTS.timeval.__size__ }}} + {{{ C_STRUCTS.timeval.tv_usec }}};
      time += {{{ makeGetValue('times', 'offset', 'i32') }}} / 1000;
    } else {
      time = Date.now();
    }
    path = Pointer_stringify(path);
    try {
      FS.utime(path, time, time);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  // ==========================================================================
  // libgen.h
  // ==========================================================================

  __libgenSplitName: function(path) {
    if (path === 0 || {{{ makeGetValue('path', 0, 'i8') }}} === 0) {
      // Null or empty results in '.'.
      var me = ___libgenSplitName;
      if (!me.ret) {
        me.ret = allocate([{{{ charCode('.') }}}, 0], 'i8', ALLOC_NORMAL);
      }
      return [me.ret, -1];
    } else {
      var slash = {{{ charCode('/') }}};
      var allSlashes = true;
      var slashPositions = [];
      for (var i = 0; {{{ makeGetValue('path', 'i', 'i8') }}} !== 0; i++) {
        if ({{{ makeGetValue('path', 'i', 'i8') }}} === slash) {
          slashPositions.push(i);
        } else {
          allSlashes = false;
        }
      }
      var length = i;
      if (allSlashes) {
        // All slashes result in a single slash.
        {{{ makeSetValue('path', '1', '0', 'i8') }}};
        return [path, -1];
      } else {
        // Strip trailing slashes.
        while (slashPositions.length &&
               slashPositions[slashPositions.length - 1] == length - 1) {
          {{{ makeSetValue('path', 'slashPositions.pop(i)', '0', 'i8') }}};
          length--;
        }
        return [path, slashPositions.pop()];
      }
    }
  },
  basename__deps: ['__libgenSplitName'],
  basename: function(path) {
    // char *basename(char *path);
    // http://pubs.opengroup.org/onlinepubs/007908799/xsh/basename.html
    var result = ___libgenSplitName(path);
    return result[0] + result[1] + 1;
  },
  dirname__deps: ['__libgenSplitName'],
  dirname: function(path) {
    // char *dirname(char *path);
    // http://pubs.opengroup.org/onlinepubs/007908799/xsh/dirname.html
    var result = ___libgenSplitName(path);
    if (result[1] == 0) {
      {{{ makeSetValue('result[0]', 1, '0', 'i8') }}};
    } else if (result[1] !== -1) {
      {{{ makeSetValue('result[0]', 'result[1]', '0', 'i8') }}};
    }
    return result[0];
  },

  // ==========================================================================
  // sys/stat.h
  // ==========================================================================

  stat__deps: ['$FS'],
  stat: function(path, buf, dontResolveLastLink) {
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/stat.html
    // int stat(const char *path, struct stat *buf);
    // NOTE: dontResolveLastLink is a shortcut for lstat(). It should never be
    //       used in client code.
    path = typeof path !== 'string' ? Pointer_stringify(path) : path;
    try {
      var stat = dontResolveLastLink ? FS.lstat(path) : FS.stat(path);
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_dev, 'stat.dev', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.__st_dev_padding, '0', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.__st_ino_truncated, 'stat.ino', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_mode, 'stat.mode', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_nlink, 'stat.nlink', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_uid, 'stat.uid', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_gid, 'stat.gid', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_rdev, 'stat.rdev', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.__st_rdev_padding, '0', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_size, 'stat.size', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_blksize, '4096', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_blocks, 'stat.blocks', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_atim.tv_sec, '(stat.atime.getTime() / 1000)|0', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_atim.tv_nsec, '0', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_mtim.tv_sec, '(stat.mtime.getTime() / 1000)|0', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_mtim.tv_nsec, '0', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_ctim.tv_sec, '(stat.ctime.getTime() / 1000)|0', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_ctim.tv_nsec, '0', 'i32') }}};
      {{{ makeSetValue('buf', C_STRUCTS.stat.st_ino, 'stat.ino', 'i32') }}};
      return 0;
    } catch (e) {
      if (e.node && PATH.normalize(path) !== PATH.normalize(FS.getPath(e.node))) {
        // an error occurred while trying to look up the path; we should just report ENOTDIR
        e.setErrno(ERRNO_CODES.ENOTDIR);
      }
      FS.handleFSError(e);
      return -1;
    }
  },
  lstat__deps: ['stat'],
  lstat: function(path, buf) {
    // int lstat(const char *path, struct stat *buf);
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/lstat.html
    return _stat(path, buf, true);
  },
  fstat__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'stat'],
  fstat: function(fildes, buf) {
    // int fstat(int fildes, struct stat *buf);
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/fstat.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    return _stat(stream.path, buf);
  },
  mknod__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  mknod: function(path, mode, dev) {
    // int mknod(const char *path, mode_t mode, dev_t dev);
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/mknod.html
    path = Pointer_stringify(path);
    // we don't want this in the JS API as the JS API
    // uses mknod to create all nodes.
    switch (mode & {{{ cDefine('S_IFMT') }}}) {
      case {{{ cDefine('S_IFREG') }}}:
      case {{{ cDefine('S_IFCHR') }}}:
      case {{{ cDefine('S_IFBLK') }}}:
      case {{{ cDefine('S_IFIFO') }}}:
      case {{{ cDefine('S_IFSOCK') }}}:
        break;
      default:
        ___setErrNo(ERRNO_CODES.EINVAL);
        return -1;
    }
    try {
      FS.mknod(path, mode, dev);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  mkdir__deps: ['mknod'],
  mkdir: function(path, mode) {
    // int mkdir(const char *path, mode_t mode);
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/mkdir.html
    path = Pointer_stringify(path);
    // remove a trailing slash, if one - /a/b/ has basename of '', but
    // we want to create b in the context of this function
    path = PATH.normalize(path);
    if (path[path.length-1] === '/') path = path.substr(0, path.length-1);
    try {
      FS.mkdir(path, mode, 0);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  mkfifo__deps: ['__setErrNo', '$ERRNO_CODES'],
  mkfifo: function(path, mode) {
    // int mkfifo(const char *path, mode_t mode);
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/mkfifo.html
    // NOTE: We support running only a single process, and named pipes require
    //       blocking, which we can't provide. The error code is not very
    //       accurate, but it's the closest among those allowed in the standard
    //       and unlikely to result in retries.
    ___setErrNo(ERRNO_CODES.EROFS);
    return -1;
  },
  chmod__deps: ['$FS', '__setErrNo'],
  chmod: function(path, mode, dontResolveLastLink) {
    // int chmod(const char *path, mode_t mode);
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/chmod.html
    // NOTE: dontResolveLastLink is a shortcut for lchmod(). It should never be
    //       used in client code.
    path = typeof path !== 'string' ? Pointer_stringify(path) : path;
    try {
      FS.chmod(path, mode);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  fchmod__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'chmod'],
  fchmod: function(fildes, mode) {
    // int fchmod(int fildes, mode_t mode);
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/fchmod.html
    try {
      FS.fchmod(fildes, mode);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  lchmod__deps: ['chmod'],
  lchmod: function(path, mode) {
    path = Pointer_stringify(path);
    try {
      FS.lchmod(path, mode);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  umask__deps: ['$FS'],
  umask: function(newMask) {
    // mode_t umask(mode_t cmask);
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/umask.html
    // NOTE: This value isn't actually used for anything.
    if (_umask.cmask === undefined) _umask.cmask = 0x1FF;  // S_IRWXU | S_IRWXG | S_IRWXO.
    var oldMask = _umask.cmask;
    _umask.cmask = newMask;
    return oldMask;
  },

  // ==========================================================================
  // sys/statvfs.h
  // ==========================================================================

  statvfs__deps: ['$FS'],
  statvfs: function(path, buf) {
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/statvfs.html
    // int statvfs(const char *restrict path, struct statvfs *restrict buf);
    // NOTE: None of the constants here are true. We're just returning safe and
    //       sane values.
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_bsize, '4096', 'i32') }}};
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_frsize, '4096', 'i32') }}};
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_blocks, '1000000', 'i32') }}};
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_bfree, '500000', 'i32') }}};
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_bavail, '500000', 'i32') }}};
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_files, 'FS.nextInode', 'i32') }}};
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_ffree, '1000000', 'i32') }}};
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_favail, '1000000', 'i32') }}};
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_fsid, '42', 'i32') }}};
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_flag, '2', 'i32') }}};  // ST_NOSUID
    {{{ makeSetValue('buf', C_STRUCTS.statvfs.f_namemax, '255', 'i32') }}};
    return 0;
  },
  fstatvfs__deps: ['statvfs'],
  fstatvfs: function(fildes, buf) {
    // int fstatvfs(int fildes, struct statvfs *buf);
    // http://pubs.opengroup.org/onlinepubs/009604499/functions/statvfs.html
    return _statvfs(0, buf);
  },

  // ==========================================================================
  // fcntl.h
  // ==========================================================================

  open__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  open: function(path, oflag, varargs) {
    // int open(const char *path, int oflag, ...);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/open.html
    var mode = {{{ makeGetValue('varargs', 0, 'i32') }}};
    path = Pointer_stringify(path);
    try {
      var stream = FS.open(path, oflag, mode);
      return stream.fd;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  creat__deps: ['open'],
  creat: function(path, mode) {
    // int creat(const char *path, mode_t mode);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/creat.html
    return _open(path, {{{ cDefine('O_WRONLY') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_TRUNC') }}}, allocate([mode, 0, 0, 0], 'i32', ALLOC_STACK));
  },
  mktemp: function(template) {
    if (!_mktemp.counter) _mktemp.counter = 0;
    var c = (_mktemp.counter++).toString();
    var rep = 'XXXXXX';
    while (c.length < rep.length) c = '0' + c;
    writeArrayToMemory(intArrayFromString(c), template + Pointer_stringify(template).indexOf(rep));
    return template;
  },
  mkstemp__deps: ['creat', 'mktemp'],
  mkstemp: function(template) {
    return _creat(_mktemp(template), 0600);
  },
  mkdtemp__deps: ['mktemp', 'mkdir'],
  mkdtemp: function(template) {
    template = _mktemp(template);
    return (_mkdir(template, 0700) === 0) ? template : 0;
  },
  fcntl__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  fcntl: function(fildes, cmd, varargs, dup2) {
    // int fcntl(int fildes, int cmd, ...);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/fcntl.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    switch (cmd) {
      case {{{ cDefine('F_DUPFD') }}}:
        var arg = {{{ makeGetValue('varargs', 0, 'i32') }}};
        if (arg < 0) {
          ___setErrNo(ERRNO_CODES.EINVAL);
          return -1;
        }
        var newStream;
        try {
          newStream = FS.open(stream.path, stream.flags, 0, arg);
        } catch (e) {
          FS.handleFSError(e);
          return -1;
        }
        return newStream.fd;
      case {{{ cDefine('F_GETFD') }}}:
      case {{{ cDefine('F_SETFD') }}}:
        return 0;  // FD_CLOEXEC makes no sense for a single process.
      case {{{ cDefine('F_GETFL') }}}:
        return stream.flags;
      case {{{ cDefine('F_SETFL') }}}:
        var arg = {{{ makeGetValue('varargs', 0, 'i32') }}};
        stream.flags |= arg;
        return 0;
      case {{{ cDefine('F_GETLK') }}}:
      case {{{ cDefine('F_GETLK64') }}}:
        var arg = {{{ makeGetValue('varargs', 0, 'i32') }}};
        var offset = {{{ C_STRUCTS.flock.l_type }}};
        // We're always unlocked.
        {{{ makeSetValue('arg', 'offset', cDefine('F_UNLCK'), 'i16') }}};
        return 0;
      case {{{ cDefine('F_SETLK') }}}:
      case {{{ cDefine('F_SETLKW') }}}:
      case {{{ cDefine('F_SETLK64') }}}:
      case {{{ cDefine('F_SETLKW64') }}}:
        // Pretend that the locking is successful.
        return 0;
      case {{{ cDefine('F_SETOWN') }}}:
      case {{{ cDefine('F_GETOWN') }}}:
        // These are for sockets. We don't have them fully implemented yet.
        ___setErrNo(ERRNO_CODES.EINVAL);
        return -1;
      default:
        ___setErrNo(ERRNO_CODES.EINVAL);
        return -1;
    }
    // Should never be reached. Only to silence strict warnings.
    return -1;
  },
  posix_fadvise: function(fd, offset, len, advice) {
    // int posix_fadvise(int fd, off_t offset, off_t len, int advice);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/posix_fadvise.html
    // Advise as much as you wish. We don't care.
    return 0;
  },
  posix_madvise: function(){ return 0 }, // ditto as fadvise
  posix_fallocate__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  posix_fallocate: function(fd, offset, len) {
    // int posix_fallocate(int fd, off_t offset, off_t len);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/posix_fallocate.html
    var stream = FS.getStream(fd);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    try {
      FS.allocate(stream, offset, len);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  // ==========================================================================
  // sys/file.h
  // ==========================================================================

  flock: function(fd, operation) {
    // int flock(int fd, int operation);
    // Pretend to succeed
    return 0;
  },

  // ==========================================================================
  // nl_types.h
  // ==========================================================================

  catopen: function(name, oflag) {
    // nl_catd catopen (const char *name, int oflag)
    return -1;
  },

  catgets: function(catd, set_id, msg_id, s) {
    // char *catgets (nl_catd catd, int set_id, int msg_id, const char *s)
    return s;
  },

  catclose: function(catd) {
    // int catclose (nl_catd catd)
    return 0;
  },

  // ==========================================================================
  // poll.h
  // ==========================================================================

  __DEFAULT_POLLMASK: {{{ cDefine('POLLIN') }}} | {{{ cDefine('POLLOUT') }}},
  poll__deps: ['$FS', '__DEFAULT_POLLMASK'],
  poll: function(fds, nfds, timeout) {
    // int poll(struct pollfd fds[], nfds_t nfds, int timeout);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/poll.html
    var nonzero = 0;
    for (var i = 0; i < nfds; i++) {
      var pollfd = fds + {{{ C_STRUCTS.pollfd.__size__ }}} * i;
      var fd = {{{ makeGetValue('pollfd', C_STRUCTS.pollfd.fd, 'i32') }}};
      var events = {{{ makeGetValue('pollfd', C_STRUCTS.pollfd.events, 'i16') }}};
      var mask = {{{ cDefine('POLLNVAL') }}};
      var stream = FS.getStream(fd);
      if (stream) {
        mask = ___DEFAULT_POLLMASK;
        if (stream.stream_ops.poll) {
          mask = stream.stream_ops.poll(stream);
        }
      }
      mask &= events | {{{ cDefine('POLLERR') }}} | {{{ cDefine('POLLHUP') }}};
      if (mask) nonzero++;
      {{{ makeSetValue('pollfd', C_STRUCTS.pollfd.revents, 'mask', 'i16') }}};
    }
    return nonzero;
  },

  // ==========================================================================
  // unistd.h
  // ==========================================================================

  access__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  access: function(path, amode) {
    // int access(const char *path, int amode);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/access.html
    path = Pointer_stringify(path);
    if (amode & ~{{{ cDefine('S_IRWXO') }}}) {
      // need a valid mode
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    }
    var node;
    try {
      var lookup = FS.lookupPath(path, { follow: true });
      node = lookup.node;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
    var perms = '';
    if (amode & {{{ cDefine('R_OK') }}}) perms += 'r';
    if (amode & {{{ cDefine('W_OK') }}}) perms += 'w';
    if (amode & {{{ cDefine('X_OK') }}}) perms += 'x';
    if (perms /* otherwise, they've just passed F_OK */ && FS.nodePermissions(node, perms)) {
      ___setErrNo(ERRNO_CODES.EACCES);
      return -1;
    }
    return 0;
  },
  chdir__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  chdir: function(path) {
    // int chdir(const char *path);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/chdir.html
    // NOTE: The path argument may be a string, to simplify fchdir().
    if (typeof path !== 'string') path = Pointer_stringify(path);
    try {
      FS.chdir(path);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  chown__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  chown: function(path, owner, group, dontResolveLastLink) {
    // int chown(const char *path, uid_t owner, gid_t group);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/chown.html
    // We don't support multiple users, so changing ownership makes no sense.
    // NOTE: The path argument may be a string, to simplify fchown().
    // NOTE: dontResolveLastLink is a shortcut for lchown(). It should never be
    //       used in client code.
    if (typeof path !== 'string') path = Pointer_stringify(path);
    try {
      FS.chown(path, owner, group);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  chroot__deps: ['__setErrNo', '$ERRNO_CODES'],
  chroot: function(path) {
    // int chroot(const char *path);
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/chroot.html
    ___setErrNo(ERRNO_CODES.EACCES);
    return -1;
  },
  close__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  close: function(fildes) {
    // int close(int fildes);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/close.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    try {
      FS.close(stream);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  dup__deps: ['fcntl'],
  dup: function(fildes) {
    // int dup(int fildes);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/dup.html
    return _fcntl(fildes, 0, allocate([0, 0, 0, 0], 'i32', ALLOC_STACK));  // F_DUPFD.
  },
  dup2__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'fcntl', 'close'],
  dup2: function(fildes, fildes2) {
    // int dup2(int fildes, int fildes2);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/dup.html
    var stream = FS.getStream(fildes);
    if (fildes2 < 0) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    } else if (fildes === fildes2 && stream) {
      return fildes;
    } else {
      _close(fildes2);
      try {
        var stream2 = FS.open(stream.path, stream.flags, 0, fildes2, fildes2);
        return stream2.fd;
      } catch (e) {
        FS.handleFSError(e);
        return -1;
      }
    }
  },
  fchown__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'chown'],
  fchown: function(fildes, owner, group) {
    // int fchown(int fildes, uid_t owner, gid_t group);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fchown.html
    try {
      FS.fchown(fildes, owner, group);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  fchdir__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'chdir'],
  fchdir: function(fildes) {
    // int fchdir(int fildes);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fchdir.html
    var stream = FS.getStream(fildes);
    if (stream) {
      return _chdir(stream.path);
    } else {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
  },
  ctermid__deps: ['strcpy'],
  ctermid: function(s) {
    // char *ctermid(char *s);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/ctermid.html
    if (!_ctermid.ret) {
      var arr = intArrayFromString('/dev/tty');
      _ctermid.ret = allocate(arr, 'i8', ALLOC_NORMAL);
    }
    return s ? _strcpy(s, _ctermid.ret) : _ctermid.ret;
  },
  crypt: function(key, salt) {
    // char *(const char *, const char *);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/crypt.html
    // TODO: Implement (probably compile from C).
    ___setErrNo(ERRNO_CODES.ENOSYS);
#if ASSERTIONS
    Runtime.warnOnce('crypt() returning an error as we do not support it');
#endif
    return 0;
  },
  encrypt: function(block, edflag) {
    // void encrypt(char block[64], int edflag);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/encrypt.html
    // TODO: Implement (probably compile from C).
#if ASSERTIONS
    Runtime.warnOnce('encrypt() returning an error as we do not support it');
#endif
    ___setErrNo(ERRNO_CODES.ENOSYS);
  },
  fpathconf__deps: ['__setErrNo', '$ERRNO_CODES'],
  fpathconf: function(fildes, name) {
    // long fpathconf(int fildes, int name);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/encrypt.html
    // NOTE: The first parameter is ignored, so pathconf == fpathconf.
    // The constants here aren't real values. Just mimicking glibc.
    switch (name) {
      case {{{ cDefine('_PC_LINK_MAX') }}}:
        return 32000;
      case {{{ cDefine('_PC_MAX_CANON') }}}:
      case {{{ cDefine('_PC_MAX_INPUT') }}}:
      case {{{ cDefine('_PC_NAME_MAX') }}}:
        return 255;
      case {{{ cDefine('_PC_PATH_MAX') }}}:
      case {{{ cDefine('_PC_PIPE_BUF') }}}:
      case {{{ cDefine('_PC_REC_MIN_XFER_SIZE') }}}:
      case {{{ cDefine('_PC_REC_XFER_ALIGN') }}}:
      case {{{ cDefine('_PC_ALLOC_SIZE_MIN') }}}:
        return 4096;
      case {{{ cDefine('_PC_CHOWN_RESTRICTED') }}}:
      case {{{ cDefine('_PC_NO_TRUNC') }}}:
      case {{{ cDefine('_PC_2_SYMLINKS') }}}:
        return 1;
      case {{{ cDefine('_PC_VDISABLE') }}}:
        return 0;
      case {{{ cDefine('_PC_SYNC_IO') }}}:
      case {{{ cDefine('_PC_ASYNC_IO') }}}:
      case {{{ cDefine('_PC_PRIO_IO') }}}:
      case {{{ cDefine('_PC_SOCK_MAXBUF') }}}:
      case {{{ cDefine('_PC_REC_INCR_XFER_SIZE') }}}:
      case {{{ cDefine('_PC_REC_MAX_XFER_SIZE') }}}:
      case {{{ cDefine('_PC_SYMLINK_MAX') }}}:
        return -1;
      case {{{ cDefine('_PC_FILESIZEBITS') }}}:
        return 64;
    }
    ___setErrNo(ERRNO_CODES.EINVAL);
    return -1;
  },
  pathconf: 'fpathconf',
#if EMTERPRETIFY_ASYNC
  fsync__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', '$EmterpreterAsync'],
  fsync: function(fildes) {
    return EmterpreterAsync.handle(function(resume) {
      // int fsync(int fildes);
      // http://pubs.opengroup.org/onlinepubs/000095399/functions/fsync.html
      var stream = FS.getStream(fildes);
      if (stream) {
        var mount = stream.node.mount;
        if (!mount.type.syncfs) {
          // We write directly to the file system, so there's nothing to do here.
          resume(function() { return 0 });
          return;
        }
        mount.type.syncfs(mount, false, function(err) {
          if (err) {
            ___setErrNo(ERRNO_CODES.EIO);
            resume(function() { return -1 });
            return;
          }
          resume(function() { return 0 });
        });
      } else {
        ___setErrNo(ERRNO_CODES.EBADF);
        resume(function() { return -1 });
      }
    });
  },
#else
  fsync__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  fsync: function(fildes) {
    // int fsync(int fildes);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fsync.html
    var stream = FS.getStream(fildes);
    if (stream) {
      // We write directly to the file system, so there's nothing to do here.
      return 0;
    } else {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
  },
#endif // EMTERPRETIFY_ASYNC
  fdatasync: 'fsync',
  truncate__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  truncate: function(path, length) {
    // int truncate(const char *path, off_t length);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/truncate.html
    // NOTE: The path argument may be a string, to simplify ftruncate().
    if (typeof path !== 'string') path = Pointer_stringify(path);
    try {
      FS.truncate(path, length);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  ftruncate__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'truncate'],
  ftruncate: function(fildes, length) {
    // int ftruncate(int fildes, off_t length);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/ftruncate.html
    try {
      FS.ftruncate(fildes, length);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  getcwd__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  getcwd: function(buf, size) {
    // char *getcwd(char *buf, size_t size);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/getcwd.html
    if (size == 0) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return 0;
    }
    var cwd = FS.cwd();
    if (size < cwd.length + 1) {
      ___setErrNo(ERRNO_CODES.ERANGE);
      return 0;
    } else {
      writeAsciiToMemory(cwd, buf);
      return buf;
    }
  },
  isatty__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  isatty: function(fildes) {
    // int isatty(int fildes);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/isatty.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return 0;
    }
    // HACK - implement tcgetattr
    if (!stream.tty) {
      ___setErrNo(ERRNO_CODES.ENOTTY);
      return 0;
    }
    return 1;
  },
  lchown__deps: ['chown'],
  lchown: function(path, owner, group) {
    // int lchown(const char *path, uid_t owner, gid_t group);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/lchown.html
    return _chown(path, owner, group, true);
  },
  link__deps: ['__setErrNo', '$ERRNO_CODES'],
  link: function(path1, path2) {
    // int link(const char *path1, const char *path2);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/link.html
    // We don't support hard links.
    ___setErrNo(ERRNO_CODES.EMLINK);
    return -1;
  },
  lockf__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  lockf: function(fildes, func, size) {
    // int lockf(int fildes, int function, off_t size);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/lockf.html
    var stream = FS.getStream(fildes);
    if (stream) {
      // Pretend whatever locking or unlocking operation succeeded. Locking does
      // not make much sense, since we have a single process/thread.
      return 0;
    } else {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
  },
  lseek__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  lseek: function(fildes, offset, whence) {
    // off_t lseek(int fildes, off_t offset, int whence);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/lseek.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    try {
      return FS.llseek(stream, offset, whence);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  pipe__deps: ['__setErrNo', '$ERRNO_CODES'],
  pipe: function(fildes) {
    // int pipe(int fildes[2]);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/pipe.html
    // It is possible to implement this using two device streams, but pipes make
    // little sense in a single-threaded environment, so we do not support them.
    ___setErrNo(ERRNO_CODES.ENOSYS);
#if ASSERTIONS
    Runtime.warnOnce('pipe() returning an error as we do not support them');
#endif
    return -1;
  },
  pread__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  pread: function(fildes, buf, nbyte, offset) {
    // ssize_t pread(int fildes, void *buf, size_t nbyte, off_t offset);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/read.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    try {
      var slab = {{{ makeGetSlabs('buf', 'i8', true) }}};
      return FS.read(stream, slab, buf, nbyte, offset);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  read__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'recv', 'pread'],
  read: function(fildes, buf, nbyte) {
    // ssize_t read(int fildes, void *buf, size_t nbyte);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/read.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }

#if SOCKET_WEBRTC
    if (stream && ('socket' in stream)) {
      return _recv(fildes, buf, nbyte, 0);
    }
#endif

    try {
      var slab = {{{ makeGetSlabs('buf', 'i8', true) }}};
      return FS.read(stream, slab, buf, nbyte);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  sync: function() {
    // void sync(void);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/sync.html
    // All our writing is already synchronized. This is a no-op.
  },
  rmdir__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  rmdir: function(path) {
    // int rmdir(const char *path);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/rmdir.html
    path = Pointer_stringify(path);
    try {
      FS.rmdir(path);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  unlink__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  unlink: function(path) {
    // int unlink(const char *path);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/unlink.html
    path = Pointer_stringify(path);
    try {
      FS.unlink(path);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  ttyname__deps: ['ttyname_r'],
  ttyname: function(fildes) {
    // char *ttyname(int fildes);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/ttyname.html
    if (!_ttyname.ret) _ttyname.ret = _malloc(256);
    return _ttyname_r(fildes, _ttyname.ret, 256) ? 0 : _ttyname.ret;
  },
  ttyname_r__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'isatty'],
  ttyname_r: function(fildes, name, namesize) {
    // int ttyname_r(int fildes, char *name, size_t namesize);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/ttyname.html
    var stream = FS.getStream(fildes);
    var ttyname = '/dev/tty';
    if (!stream) {
      return ___setErrNo(ERRNO_CODES.EBADF);
    } else if (!_isatty(fildes)) {
       return ___setErrNo(ERRNO_CODES.ENOTTY);
    } else if (namesize < ttyname.length + 1) {
      return ___setErrNo(ERRNO_CODES.ERANGE);
    }
    writeStringToMemory(ttyname, name);
    return 0;
  },
  symlink__deps: ['$FS', '$PATH', '__setErrNo', '$ERRNO_CODES'],
  symlink: function(path1, path2) {
    // int symlink(const char *path1, const char *path2);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/symlink.html
    path1 = Pointer_stringify(path1);
    path2 = Pointer_stringify(path2);
    try {
      FS.symlink(path1, path2);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  readlink__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  readlink: function(path, buf, bufsize) {
    // ssize_t readlink(const char *restrict path, char *restrict buf, size_t bufsize);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/readlink.html
    path = Pointer_stringify(path);
    var str;
    try {
      str = FS.readlink(path);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
    str = str.slice(0, Math.max(0, bufsize - 1));
    writeStringToMemory(str, buf, true);
    return str.length;
  },
  pwrite__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  pwrite: function(fildes, buf, nbyte, offset) {
    // ssize_t pwrite(int fildes, const void *buf, size_t nbyte, off_t offset);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/write.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    try {
      var slab = {{{ makeGetSlabs('buf', 'i8', true) }}};
      return FS.write(stream, slab, buf, nbyte, offset);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  write__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'send', 'pwrite'],
  write: function(fildes, buf, nbyte) {
    // ssize_t write(int fildes, const void *buf, size_t nbyte);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/write.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }

#if SOCKET_WEBRTC
    if (stream && ('socket' in stream)) {
      return _send(fildes, buf, nbyte, 0);
    }
#endif

    try {
      var slab = {{{ makeGetSlabs('buf', 'i8', true) }}};
      return FS.write(stream, slab, buf, nbyte);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  confstr__deps: ['__setErrNo', '$ERRNO_CODES', '$ENV'],
  confstr: function(name, buf, len) {
    // size_t confstr(int name, char *buf, size_t len);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/confstr.html
    var value;
    switch (name) {
      case {{{ cDefine('_CS_PATH') }}}:
        value = ENV['PATH'] || '/';
        break;
      case {{{ cDefine('_CS_POSIX_V6_WIDTH_RESTRICTED_ENVS') }}}:
        // Mimicking glibc.
        value = 'POSIX_V6_ILP32_OFF32\nPOSIX_V6_ILP32_OFFBIG';
        break;
      case {{{ cDefine('_CS_GNU_LIBC_VERSION') }}}:
        // This JS implementation was tested against this glibc version.
        value = 'glibc 2.14';
        break;
      case {{{ cDefine('_CS_GNU_LIBPTHREAD_VERSION') }}}:
        // We don't support pthreads.
        value = '';
        break;
      case {{{ cDefine('_CS_POSIX_V6_ILP32_OFF32_LIBS') }}}:
      case {{{ cDefine('_CS_POSIX_V6_ILP32_OFFBIG_LIBS') }}}:
      case {{{ cDefine('_CS_POSIX_V6_LP64_OFF64_CFLAGS') }}}:
      case {{{ cDefine('_CS_POSIX_V6_LP64_OFF64_LDFLAGS') }}}:
      case {{{ cDefine('_CS_POSIX_V6_LP64_OFF64_LIBS') }}}:
      case {{{ cDefine('_CS_POSIX_V6_LPBIG_OFFBIG_CFLAGS') }}}:
      case {{{ cDefine('_CS_POSIX_V6_LPBIG_OFFBIG_LDFLAGS') }}}:
      case {{{ cDefine('_CS_POSIX_V6_LPBIG_OFFBIG_LIBS') }}}:
        value = '';
        break;
      case {{{ cDefine('_CS_POSIX_V6_ILP32_OFF32_CFLAGS') }}}:
      case {{{ cDefine('_CS_POSIX_V6_ILP32_OFF32_LDFLAGS') }}}:
      case {{{ cDefine('_CS_POSIX_V6_ILP32_OFFBIG_LDFLAGS') }}}:
        value = '-m32';
        break;
      case {{{ cDefine('_CS_POSIX_V6_ILP32_OFFBIG_CFLAGS') }}}:
        value = '-m32 -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64';
        break;
      default:
        ___setErrNo(ERRNO_CODES.EINVAL);
        return 0;
    }
    if (len == 0 || buf == 0) {
      return value.length + 1;
    } else {
      var length = Math.min(len, value.length);
      for (var i = 0; i < length; i++) {
        {{{ makeSetValue('buf', 'i', 'value.charCodeAt(i)', 'i8') }}};
      }
      if (len > length) {{{ makeSetValue('buf', 'i++', '0', 'i8') }}};
      return i;
    }
  },
  execl__deps: ['__setErrNo', '$ERRNO_CODES'],
  execl: function(/* ... */) {
    // int execl(const char *path, const char *arg0, ... /*, (char *)0 */);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/exec.html
    // We don't support executing external code.
    ___setErrNo(ERRNO_CODES.ENOEXEC);
    return -1;
  },
  execle: 'execl',
  execlp: 'execl',
  execv: 'execl',
  execve: 'execl',
  execvp: 'execl',
  _exit: function(status) {
    // void _exit(int status);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/exit.html
    Module['exit'](status);
  },
  fork__deps: ['__setErrNo', '$ERRNO_CODES'],
  fork: function() {
    // pid_t fork(void);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fork.html
    // We don't support multiple processes.
    ___setErrNo(ERRNO_CODES.EAGAIN);
    return -1;
  },
  vfork: 'fork',

  getpid__deps: ['$PROCINFO'],
  getpid: function() {  return PROCINFO.pid;  },

  getppid__deps: ['$PROCINFO'],
  getppid: function() { return PROCINFO.ppid; },

  getpgrp__deps: ['$PROCINFO'],
  getpgrp: function() { return PROCINFO.pgid; },
  setpgrp: function() { return 0; },

  getsid__deps: ['__setErrNo', '$ERRNO_CODES', '$PROCINFO'],
  getsid: function(pid) {
    if (pid && pid != PROCINFO.pid) {
      ___setErrNo(ERRNO_CODES.ESRCH);
      return -1;
    }
    return PROCINFO.sid;
  },
  setsid: function() { return 0; },

  getpgid__deps: ['__setErrNo', '$ERRNO_CODES', '$PROCINFO'],
  getpgid: function(pid) {
    if (pid && pid != PROCINFO.pid) {
      ___setErrNo(ERRNO_CODES.ESRCH);
      return -1;
    }
    return PROCINFO.pgid;
  },
  setpgid__deps: ['__setErrNo', '$ERRNO_CODES', '$PROCINFO'],
  setpgid: function(pid, pgid) {
    if (pid && pid != PROCINFO.pid) {
      ___setErrNo(ERRNO_CODES.ESRCH);
      return -1;
    }
    if (pgid != PROCINFO.pgid) {
      ___setErrNo(ERRNO_CODES.EPERM);
      return -1;
    }
    return 0; // TODO: call setpgrp()
  },
  tcgetpgrp__deps: ['$PROCINFO'],
  tcgetpgrp: function(fildes) {
    // TODO: check that filedes is terminal
    return PROCINFO.pgid;
  },
  tcsetpgrp__deps: ['__setErrNo', '$ERRNO_CODES', '$PROCINFO'],
  tcsetpgrp: function(fildes, pgid_id) {
    // TODO: check that filedes is terminal
    if (pgid_id != PROCINFO.pgid) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    }
    return 0;
  },

  getuid: function() { return 0; },

  setuid__deps: ['__setErrNo', '$ERRNO_CODES'],
  setuid: function(uid) {
    if (uid != 0) {
      ___setErrNo(ERRNO_CODES.EPERM);
      return -1;
    }
    return 0;
  },

  getegid: 'getgid',
  setegid: 'setgid',

  getgid:  'getuid',
  setgid:  'setuid',

  geteuid: 'getuid',
  seteuid: 'setuid',

  // NOTE: These do not match the signatures, but they all use the same stub.
  setregid: 'setgid',
  setreuid: 'setuid',

  getresuid: function(ruid, euid, suid) {
    {{{ makeSetValue('ruid', '0', '0', 'i32') }}};
    {{{ makeSetValue('euid', '0', '0', 'i32') }}};
    {{{ makeSetValue('suid', '0', '0', 'i32') }}};
    return 0;
  },
  getresgid: 'getresuid',

  // NOTE: These do not match the signatures, but they all use the same stub.
  setresuid: 'setuid',
  setresgid: 'setgid',

  getgroups__deps: ['__setErrNo', '$ERRNO_CODES'],
  getgroups: function(gidsetsize, grouplist) {
    // int getgroups(int gidsetsize, gid_t grouplist[]);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/getgroups.html
    if (gidsetsize < 1) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    } else {
      {{{ makeSetValue('grouplist', '0', '0', 'i32') }}};
      return 1;
    }
  },
  // TODO: Implement initgroups (grp.h).
  setgroups__deps: ['__setErrNo', '$ERRNO_CODES', 'sysconf'],
  setgroups: function(ngroups, gidset) {
    // int setgroups(int ngroups, const gid_t *gidset);
    // https://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man2/setgroups.2.html
    if (ngroups < 1 || ngroups > _sysconf({{{ cDefine('_SC_NGROUPS_MAX') }}})) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    } else {
      // We have just one process/user/group, so it makes no sense to set groups.
      ___setErrNo(ERRNO_CODES.EPERM);
      return -1;
    }
  },
  gethostid: function() {
    // long gethostid(void);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/gethostid.html
    return 42;
  },
  gethostname__deps: ['__setErrNo', '$ERRNO_CODES'],
  gethostname: function(name, namelen) {
    // int gethostname(char *name, size_t namelen);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/gethostname.html
    var host = 'emscripten';
    if (typeof window !== 'undefined' && window.location.host) {
      host = window.location.host;
    }
    var length = Math.min(namelen, host.length);
    for (var i = 0; i < length; i++) {
      {{{ makeSetValue('name', 'i', 'host.charCodeAt(i)', 'i8') }}};
    }
    if (namelen > length) {
      {{{ makeSetValue('name', 'i', '0', 'i8') }}};
      return 0;
    } else {
      ___setErrNo(ERRNO_CODES.ENAMETOOLONG);
      return -1;
    }
  },
  getlogin__deps: ['getlogin_r'],
  getlogin: function() {
    // char *getlogin(void);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/getlogin.html
    if (!_getlogin.ret) _getlogin.ret = _malloc(8);
    return _getlogin_r(_getlogin.ret, 8) ? 0 : _getlogin.ret;
  },
  getlogin_r__deps: ['__setErrNo', '$ERRNO_CODES'],
  getlogin_r: function(name, namesize) {
    // int getlogin_r(char *name, size_t namesize);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/getlogin.html
    var ret = 'root';
    if (namesize < ret.length + 1) {
      return ___setErrNo(ERRNO_CODES.ERANGE);
    } else {
      writeAsciiToMemory(ret, name);
      return 0;
    }
  },
  getpagesize: function() {
    // int getpagesize(void);
    return PAGE_SIZE;
  },
  getopt: function(argc, argv, optstring) {
    // int getopt(int argc, char * const argv[], const char *optstring);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/getopt.html
    // TODO: Implement (probably compile from C).
    return -1;
  },
  nice__deps: ['__setErrNo', '$ERRNO_CODES'],
  nice: function(incr) {
    // int nice(int incr);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/nice.html
    // Niceness makes no sense in a single-process environment.
    ___setErrNo(ERRNO_CODES.EPERM);
    return 0;
  },
  sleep__deps: ['usleep'],
  sleep: function(seconds) {
    // unsigned sleep(unsigned seconds);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/sleep.html
    return _usleep(seconds * 1e6);
  },
  usleep: function(useconds) {
    // int usleep(useconds_t useconds);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/usleep.html
    // We're single-threaded, so use a busy loop. Super-ugly.
    var msec = useconds / 1000;
    if ((ENVIRONMENT_IS_WEB || ENVIRONMENT_IS_WORKER) && self['performance'] && self['performance']['now']) {
      var start = self['performance']['now']();
      while (self['performance']['now']() - start < msec) {
        // Do nothing.
      }
    } else {
      var start = Date.now();
      while (Date.now() - start < msec) {
        // Do nothing.
      }
    }
    return 0;
  },
  swab: function(src, dest, nbytes) {
    // void swab(const void *restrict src, void *restrict dest, ssize_t nbytes);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/swab.html
    if (nbytes < 0) return;
    nbytes -= nbytes % 2;
    for (var i = 0; i < nbytes; i += 2) {
      var first = {{{ makeGetValue('src', 'i', 'i8') }}};
      var second = {{{ makeGetValue('src', 'i + 1', 'i8') }}};
      {{{ makeSetValue('dest', 'i', 'second', 'i8') }}};
      {{{ makeSetValue('dest', 'i + 1', 'first', 'i8') }}};
    }
  },
  tcgetpgrp: function(fildes) {
    // pid_t tcgetpgrp(int fildes);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/tcgetpgrp.html
    // Our only process always runs with group ID 0.
    return 0;
  },
  tcsetpgrp__deps: ['__setErrNo', '$ERRNO_CODES'],
  tcsetpgrp: function(fildes, pgid_id) {
    // int tcsetpgrp(int fildes, pid_t pgid_id);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/tcsetpgrp.html
    // We don't support multiple processes or groups with ID other than 0.
    ___setErrNo(ERRNO_CODES.EINVAL);
    return -1;
  },
  sysconf__deps: ['__setErrNo', '$ERRNO_CODES'],
  sysconf: function(name) {
    // long sysconf(int name);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/sysconf.html
    switch(name) {
      case {{{ cDefine('_SC_PAGE_SIZE') }}}: return PAGE_SIZE;
      case {{{ cDefine('_SC_PHYS_PAGES') }}}: return totalMemory / PAGE_SIZE;
      case {{{ cDefine('_SC_ADVISORY_INFO') }}}:
      case {{{ cDefine('_SC_BARRIERS') }}}:
      case {{{ cDefine('_SC_ASYNCHRONOUS_IO') }}}:
      case {{{ cDefine('_SC_CLOCK_SELECTION') }}}:
      case {{{ cDefine('_SC_CPUTIME') }}}:
      case {{{ cDefine('_SC_FSYNC') }}}:
      case {{{ cDefine('_SC_IPV6') }}}:
      case {{{ cDefine('_SC_MAPPED_FILES') }}}:
      case {{{ cDefine('_SC_MEMLOCK') }}}:
      case {{{ cDefine('_SC_MEMLOCK_RANGE') }}}:
      case {{{ cDefine('_SC_MEMORY_PROTECTION') }}}:
      case {{{ cDefine('_SC_MESSAGE_PASSING') }}}:
      case {{{ cDefine('_SC_MONOTONIC_CLOCK') }}}:
      case {{{ cDefine('_SC_PRIORITIZED_IO') }}}:
      case {{{ cDefine('_SC_PRIORITY_SCHEDULING') }}}:
      case {{{ cDefine('_SC_RAW_SOCKETS') }}}:
      case {{{ cDefine('_SC_READER_WRITER_LOCKS') }}}:
      case {{{ cDefine('_SC_REALTIME_SIGNALS') }}}:
      case {{{ cDefine('_SC_SEMAPHORES') }}}:
      case {{{ cDefine('_SC_SHARED_MEMORY_OBJECTS') }}}:
      case {{{ cDefine('_SC_SPAWN') }}}:
      case {{{ cDefine('_SC_SPIN_LOCKS') }}}:
      case {{{ cDefine('_SC_SYNCHRONIZED_IO') }}}:
      case {{{ cDefine('_SC_THREAD_ATTR_STACKADDR') }}}:
      case {{{ cDefine('_SC_THREAD_ATTR_STACKSIZE') }}}:
      case {{{ cDefine('_SC_THREAD_CPUTIME') }}}:
      case {{{ cDefine('_SC_THREAD_PRIO_INHERIT') }}}:
      case {{{ cDefine('_SC_THREAD_PRIO_PROTECT') }}}:
      case {{{ cDefine('_SC_THREAD_PRIORITY_SCHEDULING') }}}:
      case {{{ cDefine('_SC_THREAD_PROCESS_SHARED') }}}:
      case {{{ cDefine('_SC_THREAD_SAFE_FUNCTIONS') }}}:
      case {{{ cDefine('_SC_THREADS') }}}:
      case {{{ cDefine('_SC_TIMEOUTS') }}}:
      case {{{ cDefine('_SC_TIMERS') }}}:
      case {{{ cDefine('_SC_VERSION') }}}:
      case {{{ cDefine('_SC_2_C_BIND') }}}:
      case {{{ cDefine('_SC_2_C_DEV') }}}:
      case {{{ cDefine('_SC_2_CHAR_TERM') }}}:
      case {{{ cDefine('_SC_2_LOCALEDEF') }}}:
      case {{{ cDefine('_SC_2_SW_DEV') }}}:
      case {{{ cDefine('_SC_2_VERSION') }}}:
        return 200809;
      case {{{ cDefine('_SC_MQ_OPEN_MAX') }}}:
      case {{{ cDefine('_SC_XOPEN_STREAMS') }}}:
      case {{{ cDefine('_SC_XBS5_LP64_OFF64') }}}:
      case {{{ cDefine('_SC_XBS5_LPBIG_OFFBIG') }}}:
      case {{{ cDefine('_SC_AIO_LISTIO_MAX') }}}:
      case {{{ cDefine('_SC_AIO_MAX') }}}:
      case {{{ cDefine('_SC_SPORADIC_SERVER') }}}:
      case {{{ cDefine('_SC_THREAD_SPORADIC_SERVER') }}}:
      case {{{ cDefine('_SC_TRACE') }}}:
      case {{{ cDefine('_SC_TRACE_EVENT_FILTER') }}}:
      case {{{ cDefine('_SC_TRACE_EVENT_NAME_MAX') }}}:
      case {{{ cDefine('_SC_TRACE_INHERIT') }}}:
      case {{{ cDefine('_SC_TRACE_LOG') }}}:
      case {{{ cDefine('_SC_TRACE_NAME_MAX') }}}:
      case {{{ cDefine('_SC_TRACE_SYS_MAX') }}}:
      case {{{ cDefine('_SC_TRACE_USER_EVENT_MAX') }}}:
      case {{{ cDefine('_SC_TYPED_MEMORY_OBJECTS') }}}:
      case {{{ cDefine('_SC_V6_LP64_OFF64') }}}:
      case {{{ cDefine('_SC_V6_LPBIG_OFFBIG') }}}:
      case {{{ cDefine('_SC_2_FORT_DEV') }}}:
      case {{{ cDefine('_SC_2_FORT_RUN') }}}:
      case {{{ cDefine('_SC_2_PBS') }}}:
      case {{{ cDefine('_SC_2_PBS_ACCOUNTING') }}}:
      case {{{ cDefine('_SC_2_PBS_CHECKPOINT') }}}:
      case {{{ cDefine('_SC_2_PBS_LOCATE') }}}:
      case {{{ cDefine('_SC_2_PBS_MESSAGE') }}}:
      case {{{ cDefine('_SC_2_PBS_TRACK') }}}:
      case {{{ cDefine('_SC_2_UPE') }}}:
      case {{{ cDefine('_SC_THREAD_THREADS_MAX') }}}:
      case {{{ cDefine('_SC_SEM_NSEMS_MAX') }}}:
      case {{{ cDefine('_SC_SYMLOOP_MAX') }}}:
      case {{{ cDefine('_SC_TIMER_MAX') }}}:
        return -1;
      case {{{ cDefine('_SC_V6_ILP32_OFF32') }}}:
      case {{{ cDefine('_SC_V6_ILP32_OFFBIG') }}}:
      case {{{ cDefine('_SC_JOB_CONTROL') }}}:
      case {{{ cDefine('_SC_REGEXP') }}}:
      case {{{ cDefine('_SC_SAVED_IDS') }}}:
      case {{{ cDefine('_SC_SHELL') }}}:
      case {{{ cDefine('_SC_XBS5_ILP32_OFF32') }}}:
      case {{{ cDefine('_SC_XBS5_ILP32_OFFBIG') }}}:
      case {{{ cDefine('_SC_XOPEN_CRYPT') }}}:
      case {{{ cDefine('_SC_XOPEN_ENH_I18N') }}}:
      case {{{ cDefine('_SC_XOPEN_LEGACY') }}}:
      case {{{ cDefine('_SC_XOPEN_REALTIME') }}}:
      case {{{ cDefine('_SC_XOPEN_REALTIME_THREADS') }}}:
      case {{{ cDefine('_SC_XOPEN_SHM') }}}:
      case {{{ cDefine('_SC_XOPEN_UNIX') }}}:
        return 1;
      case {{{ cDefine('_SC_THREAD_KEYS_MAX') }}}:
      case {{{ cDefine('_SC_IOV_MAX') }}}:
      case {{{ cDefine('_SC_GETGR_R_SIZE_MAX') }}}:
      case {{{ cDefine('_SC_GETPW_R_SIZE_MAX') }}}:
      case {{{ cDefine('_SC_OPEN_MAX') }}}:
        return 1024;
      case {{{ cDefine('_SC_RTSIG_MAX') }}}:
      case {{{ cDefine('_SC_EXPR_NEST_MAX') }}}:
      case {{{ cDefine('_SC_TTY_NAME_MAX') }}}:
        return 32;
      case {{{ cDefine('_SC_ATEXIT_MAX') }}}:
      case {{{ cDefine('_SC_DELAYTIMER_MAX') }}}:
      case {{{ cDefine('_SC_SEM_VALUE_MAX') }}}:
        return 2147483647;
      case {{{ cDefine('_SC_SIGQUEUE_MAX') }}}:
      case {{{ cDefine('_SC_CHILD_MAX') }}}:
        return 47839;
      case {{{ cDefine('_SC_BC_SCALE_MAX') }}}:
      case {{{ cDefine('_SC_BC_BASE_MAX') }}}:
        return 99;
      case {{{ cDefine('_SC_LINE_MAX') }}}:
      case {{{ cDefine('_SC_BC_DIM_MAX') }}}:
        return 2048;
      case {{{ cDefine('_SC_ARG_MAX') }}}: return 2097152;
      case {{{ cDefine('_SC_NGROUPS_MAX') }}}: return 65536;
      case {{{ cDefine('_SC_MQ_PRIO_MAX') }}}: return 32768;
      case {{{ cDefine('_SC_RE_DUP_MAX') }}}: return 32767;
      case {{{ cDefine('_SC_THREAD_STACK_MIN') }}}: return 16384;
      case {{{ cDefine('_SC_BC_STRING_MAX') }}}: return 1000;
      case {{{ cDefine('_SC_XOPEN_VERSION') }}}: return 700;
      case {{{ cDefine('_SC_LOGIN_NAME_MAX') }}}: return 256;
      case {{{ cDefine('_SC_COLL_WEIGHTS_MAX') }}}: return 255;
      case {{{ cDefine('_SC_CLK_TCK') }}}: return 100;
      case {{{ cDefine('_SC_HOST_NAME_MAX') }}}: return 64;
      case {{{ cDefine('_SC_AIO_PRIO_DELTA_MAX') }}}: return 20;
      case {{{ cDefine('_SC_STREAM_MAX') }}}: return 16;
      case {{{ cDefine('_SC_TZNAME_MAX') }}}: return 6;
      case {{{ cDefine('_SC_THREAD_DESTRUCTOR_ITERATIONS') }}}: return 4;
      case {{{ cDefine('_SC_NPROCESSORS_ONLN') }}}: {
        if (typeof navigator === 'object') return navigator['hardwareConcurrency'] || 1;
        return 1;
      }
    }
    ___setErrNo(ERRNO_CODES.EINVAL);
    return -1;
  },
  sbrk: function(bytes) {
    // Implement a Linux-like 'memory area' for our 'process'.
    // Changes the size of the memory area by |bytes|; returns the
    // address of the previous top ('break') of the memory area
    // We control the "dynamic" memory - DYNAMIC_BASE to DYNAMICTOP
    var self = _sbrk;
    if (!self.called) {
      DYNAMICTOP = alignMemoryPage(DYNAMICTOP); // make sure we start out aligned
      self.called = true;
      assert(Runtime.dynamicAlloc);
      self.alloc = Runtime.dynamicAlloc;
      Runtime.dynamicAlloc = function() { abort('cannot dynamically allocate, sbrk now has control') };
    }
    var ret = DYNAMICTOP;
    if (bytes != 0) {
      var success = self.alloc(bytes);
      if (!success) return -1 >>> 0; // sbrk failure code
    }
    return ret;  // Previous break location.
  },

  // ==========================================================================
  // stdio.h
  // ==========================================================================

  _getFloat: function(text) {
    return /^[+-]?[0-9]*\.?[0-9]+([eE][+-]?[0-9]+)?/.exec(text);
  },

  _scanString__deps: ['_getFloat'],
  _scanString: function(format, get, unget, varargs) {
    if (!__scanString.whiteSpace) {
      __scanString.whiteSpace = {};
      __scanString.whiteSpace[{{{ charCode(' ') }}}] = 1;
      __scanString.whiteSpace[{{{ charCode('\t') }}}] = 1;
      __scanString.whiteSpace[{{{ charCode('\n') }}}] = 1;
      __scanString.whiteSpace[{{{ charCode('\v') }}}] = 1;
      __scanString.whiteSpace[{{{ charCode('\f') }}}] = 1;
      __scanString.whiteSpace[{{{ charCode('\r') }}}] = 1;
    }
    // Supports %x, %4x, %d.%d, %lld, %s, %f, %lf.
    // TODO: Support all format specifiers.
    format = Pointer_stringify(format);
    var soFar = 0;
    if (format.indexOf('%n') >= 0) {
      // need to track soFar
      var _get = get;
      get = function get() {
        soFar++;
        return _get();
      }
      var _unget = unget;
      unget = function unget() {
        soFar--;
        return _unget();
      }
    }
    var formatIndex = 0;
    var argsi = 0;
    var fields = 0;
    var argIndex = 0;
    var next;

    mainLoop:
    for (var formatIndex = 0; formatIndex < format.length;) {
      if (format[formatIndex] === '%' && format[formatIndex+1] == 'n') {
        argIndex = Runtime.prepVararg(argIndex, '*');
        var argPtr = {{{ makeGetValue('varargs', 'argIndex', 'void*') }}};
        argIndex += Runtime.getAlignSize('void*', null, true);
        {{{ makeSetValue('argPtr', 0, 'soFar', 'i32') }}};
        formatIndex += 2;
        continue;
      }

      if (format[formatIndex] === '%') {
        var nextC = format.indexOf('c', formatIndex+1);
        if (nextC > 0) {
          var maxx = 1;
          if (nextC > formatIndex+1) {
            var sub = format.substring(formatIndex+1, nextC);
            maxx = parseInt(sub);
            if (maxx != sub) maxx = 0;
          }
          if (maxx) {
            argIndex = Runtime.prepVararg(argIndex, '*');
            var argPtr = {{{ makeGetValue('varargs', 'argIndex', 'void*') }}};
            argIndex += Runtime.getAlignSize('void*', null, true);
            fields++;
            for (var i = 0; i < maxx; i++) {
              next = get();
              {{{ makeSetValue('argPtr++', 0, 'next', 'i8') }}};
              if (next === 0) return i > 0 ? fields : fields-1; // we failed to read the full length of this field
            }
            formatIndex += nextC - formatIndex + 1;
            continue;
          }
        }
      }

      // handle %[...]
      if (format[formatIndex] === '%' && format.indexOf('[', formatIndex+1) > 0) {
        var match = /\%([0-9]*)\[(\^)?(\]?[^\]]*)\]/.exec(format.substring(formatIndex));
        if (match) {
          var maxNumCharacters = parseInt(match[1]) || Infinity;
          var negateScanList = (match[2] === '^');
          var scanList = match[3];

          // expand "middle" dashs into character sets
          var middleDashMatch;
          while ((middleDashMatch = /([^\-])\-([^\-])/.exec(scanList))) {
            var rangeStartCharCode = middleDashMatch[1].charCodeAt(0);
            var rangeEndCharCode = middleDashMatch[2].charCodeAt(0);
            for (var expanded = ''; rangeStartCharCode <= rangeEndCharCode; expanded += String.fromCharCode(rangeStartCharCode++));
            scanList = scanList.replace(middleDashMatch[1] + '-' + middleDashMatch[2], expanded);
          }

          argIndex = Runtime.prepVararg(argIndex, '*');
          var argPtr = {{{ makeGetValue('varargs', 'argIndex', 'void*') }}};
          argIndex += Runtime.getAlignSize('void*', null, true);
          fields++;

          for (var i = 0; i < maxNumCharacters; i++) {
            next = get();
            if (negateScanList) {
              if (scanList.indexOf(String.fromCharCode(next)) < 0) {
                {{{ makeSetValue('argPtr++', 0, 'next', 'i8') }}};
              } else {
                unget();
                break;
              }
            } else {
              if (scanList.indexOf(String.fromCharCode(next)) >= 0) {
                {{{ makeSetValue('argPtr++', 0, 'next', 'i8') }}};
              } else {
                unget();
                break;
              }
            }
          }

          // write out null-terminating character
          {{{ makeSetValue('argPtr++', 0, '0', 'i8') }}};
          formatIndex += match[0].length;
          
          continue;
        }
      }      
      // remove whitespace
      while (1) {
        next = get();
        if (next == 0) return fields;
        if (!(next in __scanString.whiteSpace)) break;
      }
      unget();

      if (format[formatIndex] === '%') {
        formatIndex++;
        var suppressAssignment = false;
        if (format[formatIndex] == '*') {
          suppressAssignment = true;
          formatIndex++;
        }
        var maxSpecifierStart = formatIndex;
        while (format[formatIndex].charCodeAt(0) >= {{{ charCode('0') }}} &&
               format[formatIndex].charCodeAt(0) <= {{{ charCode('9') }}}) {
          formatIndex++;
        }
        var max_;
        if (formatIndex != maxSpecifierStart) {
          max_ = parseInt(format.slice(maxSpecifierStart, formatIndex), 10);
        }
        var long_ = false;
        var half = false;
        var quarter = false;
        var longLong = false;
        if (format[formatIndex] == 'l') {
          long_ = true;
          formatIndex++;
          if (format[formatIndex] == 'l') {
            longLong = true;
            formatIndex++;
          }
        } else if (format[formatIndex] == 'h') {
          half = true;
          formatIndex++;
          if (format[formatIndex] == 'h') {
            quarter = true;
            formatIndex++;
          }
        }
        var type = format[formatIndex];
        formatIndex++;
        var curr = 0;
        var buffer = [];
        // Read characters according to the format. floats are trickier, they may be in an unfloat state in the middle, then be a valid float later
        if (type == 'f' || type == 'e' || type == 'g' ||
            type == 'F' || type == 'E' || type == 'G') {
          next = get();
          while (next > 0 && (!(next in __scanString.whiteSpace)))  {
            buffer.push(String.fromCharCode(next));
            next = get();
          }
          var m = __getFloat(buffer.join(''));
          var last = m ? m[0].length : 0;
          for (var i = 0; i < buffer.length - last + 1; i++) {
            unget();
          }
          buffer.length = last;
        } else {
          next = get();
          var first = true;
          
          // Strip the optional 0x prefix for %x.
          if ((type == 'x' || type == 'X') && (next == {{{ charCode('0') }}})) {
            var peek = get();
            if (peek == {{{ charCode('x') }}} || peek == {{{ charCode('X') }}}) {
              next = get();
            } else {
              unget();
            }
          }
          
          while ((curr < max_ || isNaN(max_)) && next > 0) {
            if (!(next in __scanString.whiteSpace) && // stop on whitespace
                (type == 's' ||
                 ((type === 'd' || type == 'u' || type == 'i') && ((next >= {{{ charCode('0') }}} && next <= {{{ charCode('9') }}}) ||
                                                                   (first && next == {{{ charCode('-') }}}))) ||
                 ((type === 'x' || type === 'X') && (next >= {{{ charCode('0') }}} && next <= {{{ charCode('9') }}} ||
                                   next >= {{{ charCode('a') }}} && next <= {{{ charCode('f') }}} ||
                                   next >= {{{ charCode('A') }}} && next <= {{{ charCode('F') }}}))) &&
                (formatIndex >= format.length || next !== format[formatIndex].charCodeAt(0))) { // Stop when we read something that is coming up
              buffer.push(String.fromCharCode(next));
              next = get();
              curr++;
              first = false;
            } else {
              break;
            }
          }
          unget();
        }
        if (buffer.length === 0) return fields; // Stop here.
        if (suppressAssignment) continue;

        var text = buffer.join('');
        argIndex = Runtime.prepVararg(argIndex, '*');
        var argPtr = {{{ makeGetValue('varargs', 'argIndex', 'void*') }}};
        argIndex += Runtime.getAlignSize('void*', null, true);
        var base = 10;
        switch (type) {
          case 'X': case 'x':
            base = 16;
          case 'd': case 'u': case 'i':
            if (quarter) {
              {{{ makeSetValue('argPtr', 0, 'parseInt(text, base)', 'i8') }}};
            } else if (half) {
              {{{ makeSetValue('argPtr', 0, 'parseInt(text, base)', 'i16') }}};
            } else if (longLong) {
              {{{ makeSetValue('argPtr', 0, 'parseInt(text, base)', 'i64') }}};
            } else {
              {{{ makeSetValue('argPtr', 0, 'parseInt(text, base)', 'i32') }}};
            }
            break;
          case 'F':
          case 'f':
          case 'E':
          case 'e':
          case 'G':
          case 'g':
          case 'E':
            // fallthrough intended
            if (long_) {
              {{{ makeSetValue('argPtr', 0, 'parseFloat(text)', 'double') }}};
            } else {
              {{{ makeSetValue('argPtr', 0, 'parseFloat(text)', 'float') }}};
            }
            break;
          case 's':
            var array = intArrayFromString(text);
            for (var j = 0; j < array.length; j++) {
              {{{ makeSetValue('argPtr', 'j', 'array[j]', 'i8') }}};
            }
            break;
        }
        fields++;
      } else if (format[formatIndex].charCodeAt(0) in __scanString.whiteSpace) {
        next = get();
        while (next in __scanString.whiteSpace) {
          if (next <= 0) break mainLoop;  // End of input.
          next = get();
        }
        unget(next);
        formatIndex++;
      } else {
        // Not a specifier.
        next = get();
        if (format[formatIndex].charCodeAt(0) !== next) {
          unget(next);
          break mainLoop;
        }
        formatIndex++;
      }
    }
    return fields;
  },
  // NOTE: Invalid stream pointers passed to these functions would cause a crash
  //       in native code. We, on the other hand, just ignore them, since it's
  //       easier.
  clearerr__deps: ['$FS'],
  clearerr: function(stream) {
    // void clearerr(FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/clearerr.html
    stream = FS.getStreamFromPtr(stream);
    if (!stream) {
      return;
    }
    stream.eof = false;
    stream.error = false;
  },
  fclose__deps: ['close', 'fileno'],
  fclose: function(stream) {
    // int fclose(FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fclose.html
    var fd = _fileno(stream);
    return _close(fd);
  },
  fdopen__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  fdopen: function(fildes, mode) {
    // FILE *fdopen(int fildes, const char *mode);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fdopen.html
    mode = Pointer_stringify(mode);
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return 0;
    }
    if ((mode.indexOf('w') != -1 && !stream.isWrite) ||
        (mode.indexOf('r') != -1 && !stream.isRead) ||
        (mode.indexOf('a') != -1 && !stream.isAppend) ||
        (mode.indexOf('+') != -1 && (!stream.isRead || !stream.isWrite))) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return 0;
    } else {
      stream.error = false;
      stream.eof = false;
      return FS.getPtrForStream(stream);
    }
  },
  feof__deps: ['$FS'],
  feof: function(stream) {
    // int feof(FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/feof.html
    stream = FS.getStreamFromPtr(stream);
    return Number(stream && stream.eof);
  },
  ferror__deps: ['$FS'],
  ferror: function(stream) {
    // int ferror(FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/ferror.html
    stream = FS.getStreamFromPtr(stream);
    return Number(stream && stream.error);
  },
  fflush__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  fflush: function(stream) {
    // int fflush(FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fflush.html

    /*
    // Disabled, see https://github.com/kripken/emscripten/issues/2770
    stream = FS.getStreamFromPtr(stream);
    if (stream.stream_ops.flush) {
      stream.stream_ops.flush(stream);
    }
    */
  },
  fgetc__deps: ['$FS', 'fread'],
  fgetc__postset: '_fgetc.ret = allocate([0], "i8", ALLOC_STATIC);',
  fgetc: function(stream) {
    // int fgetc(FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fgetc.html
    var streamObj = FS.getStreamFromPtr(stream);
    if (!streamObj) return -1;
    if (streamObj.eof || streamObj.error) return -1;
    var ret = _fread(_fgetc.ret, 1, 1, stream);
    if (ret == 0) {
      return -1;
    } else if (ret == -1) {
      streamObj.error = true;
      return -1;
    } else {
      return {{{ makeGetValue('_fgetc.ret', '0', 'i8', null, 1) }}};
    }
  },
  getc: 'fgetc',
  getc_unlocked: 'fgetc',
  getchar__deps: ['fgetc', 'stdin'],
  getchar: function() {
    // int getchar(void);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/getchar.html
    return _fgetc({{{ makeGetValue(makeGlobalUse('_stdin'), '0', 'void*') }}});
  },
  fgetpos__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  fgetpos: function(stream, pos) {
    // int fgetpos(FILE *restrict stream, fpos_t *restrict pos);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fgetpos.html
    stream = FS.getStreamFromPtr(stream);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    if (FS.isChrdev(stream.node.mode)) {
      ___setErrNo(ERRNO_CODES.ESPIPE);
      return -1;
    }
    {{{ makeSetValue('pos', '0', 'stream.position', 'i32') }}};
    var state = (stream.eof ? 1 : 0) + (stream.error ? 2 : 0);
    {{{ makeSetValue('pos', Runtime.getNativeTypeSize('i32'), 'state', 'i32') }}};
    return 0;
  },
  fgets__deps: ['fgetc'],
  fgets: function(s, n, stream) {
    // char *fgets(char *restrict s, int n, FILE *restrict stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fgets.html
    var streamObj = FS.getStreamFromPtr(stream);
    if (!streamObj) return 0;
    if (streamObj.error || streamObj.eof) return 0;
    var byte_;
    for (var i = 0; i < n - 1 && byte_ != {{{ charCode('\n') }}}; i++) {
      byte_ = _fgetc(stream);
      if (byte_ == -1) {
        if (streamObj.error || (streamObj.eof && i == 0)) return 0;
        else if (streamObj.eof) break;
      }
      {{{ makeSetValue('s', 'i', 'byte_', 'i8') }}};
    }
    {{{ makeSetValue('s', 'i', '0', 'i8') }}};
    return s;
  },
  gets__deps: ['fgets'],
  gets: function(s) {
    // char *gets(char *s);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/gets.html
    return _fgets(s, 1e6, {{{ makeGetValue(makeGlobalUse('_stdin'), '0', 'void*') }}});
  },
  fileno: function(stream) {
    // int fileno(FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fileno.html
    stream = FS.getStreamFromPtr(stream);
    if (!stream) return -1;
    return stream.fd;
  },
  ftrylockfile: function() {
    // int ftrylockfile(FILE *file);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/flockfile.html
    // Locking is useless in a single-threaded environment. Pretend to succeed.
    return 0;
  },
  flockfile: 'ftrylockfile',
  funlockfile: 'ftrylockfile',
  fopen__deps: ['$FS', '__setErrNo', '$ERRNO_CODES', 'open'],
  fopen: function(filename, mode) {
    // FILE *fopen(const char *restrict filename, const char *restrict mode);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fopen.html
    var flags;
    mode = Pointer_stringify(mode);
    if (mode[0] == 'r') {
      if (mode.indexOf('+') != -1) {
        flags = {{{ cDefine('O_RDWR') }}};
      } else {
        flags = {{{ cDefine('O_RDONLY') }}};
      }
    } else if (mode[0] == 'w') {
      if (mode.indexOf('+') != -1) {
        flags = {{{ cDefine('O_RDWR') }}};
      } else {
        flags = {{{ cDefine('O_WRONLY') }}};
      }
      flags |= {{{ cDefine('O_CREAT') }}};
      flags |= {{{ cDefine('O_TRUNC') }}};
    } else if (mode[0] == 'a') {
      if (mode.indexOf('+') != -1) {
        flags = {{{ cDefine('O_RDWR') }}};
      } else {
        flags = {{{ cDefine('O_WRONLY') }}};
      }
      flags |= {{{ cDefine('O_CREAT') }}};
      flags |= {{{ cDefine('O_APPEND') }}};
    } else {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return 0;
    }
    var fd = _open(filename, flags, allocate([0x1FF, 0, 0, 0], 'i32', ALLOC_STACK));  // All creation permissions.
    return fd === -1 ? 0 : FS.getPtrForStream(FS.getStream(fd));
  },
  fputc__deps: ['$FS', 'write', 'fileno'],
  fputc__postset: '_fputc.ret = allocate([0], "i8", ALLOC_STATIC);',
  fputc: function(c, stream) {
    // int fputc(int c, FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fputc.html
    var chr = unSign(c & 0xFF);
    {{{ makeSetValue('_fputc.ret', '0', 'chr', 'i8') }}};
    var fd = _fileno(stream);
    var ret = _write(fd, _fputc.ret, 1);
    if (ret == -1) {
      var streamObj = FS.getStreamFromPtr(stream);
      if (streamObj) streamObj.error = true;
      return -1;
    } else {
      return chr;
    }
  },
  putc: 'fputc',
  putc_unlocked: 'fputc',
  putchar__deps: ['fputc', 'stdout'],
  putchar: function(c) {
    // int putchar(int c);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/putchar.html
    return _fputc(c, {{{ makeGetValue(makeGlobalUse('_stdout'), '0', 'void*') }}});
  },
  putchar_unlocked: 'putchar',
  fputs__deps: ['write', 'strlen', 'fileno'],
  fputs: function(s, stream) {
    // int fputs(const char *restrict s, FILE *restrict stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fputs.html
    var fd = _fileno(stream);
    return _write(fd, s, _strlen(s));
  },
  puts__deps: ['fputs', 'fputc', 'stdout'],
  puts: function(s) {
#if NO_FILESYSTEM == 0
    // int puts(const char *s);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/puts.html
    // NOTE: puts() always writes an extra newline.
    var stdout = {{{ makeGetValue(makeGlobalUse('_stdout'), '0', 'void*') }}};
    var ret = _fputs(s, stdout);
    if (ret < 0) {
      return ret;
    } else {
      var newlineRet = _fputc({{{ charCode('\n') }}}, stdout);
      return (newlineRet < 0) ? -1 : ret + 1;
    }
#else
    // extra effort to support puts, even without a filesystem. very partial, very hackish
    var result = Pointer_stringify(s);
    var string = result.substr(0);
    if (string[string.length-1] === '\n') string = string.substr(0, string.length-1); // remove a final \n, as Module.print will do that
    Module.print(string);
    return result.length;
#endif
  },
  fread__deps: ['$FS', 'read'],
  fread: function(ptr, size, nitems, stream) {
    // size_t fread(void *restrict ptr, size_t size, size_t nitems, FILE *restrict stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fread.html
    var bytesToRead = nitems * size;
    if (bytesToRead == 0) {
      return 0;
    }
    var bytesRead = 0;
    var streamObj = FS.getStreamFromPtr(stream);
    if (!streamObj) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return 0;
    }
    while (streamObj.ungotten.length && bytesToRead > 0) {
      {{{ makeSetValue('ptr++', '0', 'streamObj.ungotten.pop()', 'i8') }}};
      bytesToRead--;
      bytesRead++;
    }
    var err = _read(streamObj.fd, ptr, bytesToRead);
    if (err == -1) {
      if (streamObj) streamObj.error = true;
      return 0;
    }
    bytesRead += err;
    if (bytesRead < bytesToRead) streamObj.eof = true;
    return (bytesRead / size)|0;
  },
  freopen__deps: ['$FS', 'fclose', 'fopen', '__setErrNo', '$ERRNO_CODES'],
  freopen: function(filename, mode, stream) {
    // FILE *freopen(const char *restrict filename, const char *restrict mode, FILE *restrict stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/freopen.html
    if (!filename) {
      var streamObj = FS.getStreamFromPtr(stream);
      if (!streamObj) {
        ___setErrNo(ERRNO_CODES.EBADF);
        return 0;
      }
      if (_freopen.buffer) _free(_freopen.buffer);
      filename = intArrayFromString(streamObj.path);
      filename = allocate(filename, 'i8', ALLOC_NORMAL);
    }
    _fclose(stream);
    return _fopen(filename, mode);
  },
  fseek__deps: ['$FS', 'lseek', 'fileno'],
  fseek: function(stream, offset, whence) {
    // int fseek(FILE *stream, long offset, int whence);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fseek.html
    var fd = _fileno(stream);
    var ret = _lseek(fd, offset, whence);
    if (ret == -1) {
      return -1;
    }
    stream = FS.getStreamFromPtr(stream);
    stream.eof = false;
    return 0;
  },
  fseeko: 'fseek',
  fsetpos__deps: ['$FS', 'lseek', '__setErrNo', '$ERRNO_CODES'],
  fsetpos: function(stream, pos) {
    // int fsetpos(FILE *stream, const fpos_t *pos);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fsetpos.html
    stream = FS.getStreamFromPtr(stream);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    if (FS.isChrdev(stream.node.mode)) {
      ___setErrNo(ERRNO_CODES.EPIPE);
      return -1;
    }
    stream.position = {{{ makeGetValue('pos', '0', 'i32') }}};
    var state = {{{ makeGetValue('pos', Runtime.getNativeTypeSize('i32'), 'i32') }}};
    stream.eof = Boolean(state & 1);
    stream.error = Boolean(state & 2);
    return 0;
  },
  ftell__deps: ['$FS', '__setErrNo', '$ERRNO_CODES'],
  ftell: function(stream) {
    // long ftell(FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/ftell.html
    stream = FS.getStreamFromPtr(stream);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    if (FS.isChrdev(stream.node.mode)) {
      ___setErrNo(ERRNO_CODES.ESPIPE);
      return -1;
    } else {
      return stream.position;
    }
  },
  ftello: 'ftell',
  fwrite__deps: ['$FS', 'write', 'fileno'],
  fwrite: function(ptr, size, nitems, stream) {
    // size_t fwrite(const void *restrict ptr, size_t size, size_t nitems, FILE *restrict stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/fwrite.html
    var bytesToWrite = nitems * size;
    if (bytesToWrite == 0) return 0;
    var fd = _fileno(stream);
    var bytesWritten = _write(fd, ptr, bytesToWrite);
    if (bytesWritten == -1) {
      var streamObj = FS.getStreamFromPtr(stream);
      if (streamObj) streamObj.error = true;
      return 0;
    } else {
      return (bytesWritten / size)|0;
    }
  },
  popen__deps: ['__setErrNo', '$ERRNO_CODES'],
  popen: function(command, mode) {
    // FILE *popen(const char *command, const char *mode);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/popen.html
    // We allow only one process, so no pipes.
    ___setErrNo(ERRNO_CODES.EMFILE);
    return 0;
  },
  pclose__deps: ['__setErrNo', '$ERRNO_CODES'],
  pclose: function(stream) {
    // int pclose(FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/pclose.html
    // We allow only one process, so no pipes.
    ___setErrNo(ERRNO_CODES.ECHILD);
    return -1;
  },
  perror__deps: ['puts', 'fputs', 'fputc', 'strerror', '__errno_location'],
  perror: function(s) {
    // void perror(const char *s);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/perror.html
    var stdout = {{{ makeGetValue(makeGlobalUse('_stdout'), '0', 'void*') }}};
    if (s) {
      _fputs(s, stdout);
      _fputc({{{ charCode(':') }}}, stdout);
      _fputc({{{ charCode(' ') }}}, stdout);
    }
    var errnum = {{{ makeGetValue('___errno_location()', '0', 'i32') }}};
    _puts(_strerror(errnum));
  },
  remove__deps: ['unlink', 'rmdir'],
  remove: function(path) {
    // int remove(const char *path);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/remove.html
    var ret = _unlink(path);
    if (ret == -1) ret = _rmdir(path);
    return ret;
  },
  rename__deps: ['__setErrNo', '$ERRNO_CODES'],
  rename: function(old_path, new_path) {
    // int rename(const char *old, const char *new);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/rename.html
    old_path = Pointer_stringify(old_path);
    new_path = Pointer_stringify(new_path);
    try {
      FS.rename(old_path, new_path);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
  rewind__deps: ['$FS', 'fseek'],
  rewind: function(stream) {
    // void rewind(FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/rewind.html
    _fseek(stream, 0, 0);  // SEEK_SET.
    var streamObj = FS.getStreamFromPtr(stream);
    if (streamObj) streamObj.error = false;
  },
  setvbuf: function(stream, buf, type, size) {
    // int setvbuf(FILE *restrict stream, char *restrict buf, int type, size_t size);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/setvbuf.html
    // TODO: Implement custom buffering.
    return 0;
  },
  setbuf__deps: ['setvbuf'],
  setbuf: function(stream, buf) {
    // void setbuf(FILE *restrict stream, char *restrict buf);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/setbuf.html
    if (buf) _setvbuf(stream, buf, 0, 8192);  // _IOFBF, BUFSIZ.
    else _setvbuf(stream, buf, 2, 8192);  // _IONBF, BUFSIZ.
  },
  tmpnam__deps: ['$FS'],
  tmpnam: function(s, dir, prefix) {
    // char *tmpnam(char *s);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/tmpnam.html
    // NOTE: The dir and prefix arguments are for internal use only.
    dir = dir || '/tmp';
    var folder = FS.findObject(dir);
    if (!folder || !folder.isFolder) {
      dir = '/tmp';
      folder = FS.findObject(dir);
      if (!folder || !folder.isFolder) return 0;
    }
    var name = prefix || 'file';
    do {
      name += String.fromCharCode(65 + (Math.random() * 25)|0);
    } while (name in folder.contents);
    var result = dir + '/' + name;
    if (!_tmpnam.buffer) _tmpnam.buffer = _malloc(256);
    if (!s) s = _tmpnam.buffer;
    assert(result.length <= 255);
    writeAsciiToMemory(result, s);
    return s;
  },
  tempnam__deps: ['tmpnam'],
  tempnam: function(dir, pfx) {
    // char *tempnam(const char *dir, const char *pfx);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/tempnam.html
    return _tmpnam(0, Pointer_stringify(dir), Pointer_stringify(pfx));
  },
  tmpfile__deps: ['tmpnam', 'fopen'],
  tmpfile: function() {
    // FILE *tmpfile(void);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/tmpfile.html
    // TODO: Delete the created file on closing.
    if (!_tmpfile.mode) {
      _tmpfile.mode = allocate(intArrayFromString('w+'), 'i8', ALLOC_NORMAL);
    }
    return _fopen(_tmpnam(0), _tmpfile.mode);
  },
  ungetc__deps: ['$FS'],
  ungetc: function(c, stream) {
    // int ungetc(int c, FILE *stream);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/ungetc.html
    stream = FS.getStreamFromPtr(stream);
    if (!stream) {
      return -1;
    }
    if (c === {{{ cDefine('EOF') }}}) {
      // do nothing for EOF character
      return c;
    }
    c = unSign(c & 0xFF);
    stream.ungotten.push(c);
    stream.eof = false;
    return c;
  },
  system__deps: ['__setErrNo', '$ERRNO_CODES'],
  system: function(command) {
    // int system(const char *command);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/system.html
    // Can't call external programs.
    ___setErrNo(ERRNO_CODES.EAGAIN);
    return -1;
  },
  fscanf__deps: ['$FS', '_scanString', 'fgetc', 'ungetc'],
  fscanf: function(stream, format, varargs) {
    // int fscanf(FILE *restrict stream, const char *restrict format, ... );
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/scanf.html
    var streamObj = FS.getStreamFromPtr(stream);
    if (!streamObj) {
      return -1;
    }
    var buffer = [];
    function get() {
      var c = _fgetc(stream);
      buffer.push(c);
      return c;
    };
    function unget() {
      _ungetc(buffer.pop(), stream);
    };
    return __scanString(format, get, unget, varargs);
  },
  scanf__deps: ['fscanf'],
  scanf: function(format, varargs) {
    // int scanf(const char *restrict format, ... );
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/scanf.html
    var stdin = {{{ makeGetValue(makeGlobalUse('_stdin'), '0', 'void*') }}};
    return _fscanf(stdin, format, varargs);
  },
  fprintf__deps: ['fwrite', '_formatString'],
  fprintf: function(stream, format, varargs) {
    // int fprintf(FILE *restrict stream, const char *restrict format, ...);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/printf.html
    var result = __formatString(format, varargs);
    var stack = Runtime.stackSave();
    var ret = _fwrite(allocate(result, 'i8', ALLOC_STACK), 1, result.length, stream);
    Runtime.stackRestore(stack);
    return ret;
  },
  printf__deps: ['fprintf'],
  printf: function(format, varargs) {
    // int printf(const char *restrict format, ...);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/printf.html
#if NO_FILESYSTEM == 0
    var stdout = {{{ makeGetValue(makeGlobalUse('_stdout'), '0', 'void*') }}};
    return _fprintf(stdout, format, varargs);
#else
    // extra effort to support printf, even without a filesystem. very partial, very hackish
    var result = __formatString(format, varargs);
    var string = intArrayToString(result);
    if (string[string.length-1] === '\n') string = string.substr(0, string.length-1); // remove a final \n, as Module.print will do that
    Module.print(string);
    return result.length;
#endif
  },
  dprintf__deps: ['_formatString', 'write'],
  dprintf: function(fd, format, varargs) {
    var result = __formatString(format, varargs);
    var stack = Runtime.stackSave();
    var ret = _write(fd, allocate(result, 'i8', ALLOC_STACK), result.length);
    Runtime.stackRestore(stack);
  },

  // convert va_arg into varargs
  vfprintf__deps: ['fprintf'],
  vfprintf: function(s, f, va_arg) {
    return _fprintf(s, f, {{{ makeGetValue('va_arg', 0, '*') }}});
  },
  vprintf__deps: ['printf'],
  vprintf: function(format, va_arg) {
    return _printf(format, {{{ makeGetValue('va_arg', 0, '*') }}});
  },
  vdprintf__deps: ['dprintf'],
  vdprintf: function (fd, format, va_arg) {
    return _dprintf(fd, format, {{{ makeGetValue('va_arg', 0, '*') }}});
  },
  vscanf__deps: ['scanf'],
  vscanf: function(format, va_arg) {
    return _scanf(format, {{{ makeGetValue('va_arg', 0, '*') }}});
  },
  vfscanf__deps: ['fscanf'],
  vfscanf: function(s, format, va_arg) {
    return _fscanf(s, format, {{{ makeGetValue('va_arg', 0, '*') }}});
  },

  // ==========================================================================
  // sys/mman.h
  // ==========================================================================

  mmap__deps: ['$FS', 'memset'],
  mmap: function(start, num, prot, flags, fd, offset) {
    /* FIXME: Since mmap is normally implemented at the kernel level,
     * this implementation simply uses malloc underneath the call to
     * mmap.
     */
    var MAP_PRIVATE = 2;
    var ptr;
    var allocated = false;

    if (!_mmap.mappings) _mmap.mappings = {};

    if (fd == -1) {
      ptr = _malloc(num);
      if (!ptr) return -1;
      _memset(ptr, 0, num);
      allocated = true;
    } else {
      var info = FS.getStream(fd);
      if (!info) return -1;
      try {
        var res = FS.mmap(info, HEAPU8, start, num, offset, prot, flags);
        ptr = res.ptr;
        allocated = res.allocated;
      } catch (e) {
        FS.handleFSError(e);
        return -1;
      }
    }

    _mmap.mappings[ptr] = { malloc: ptr, num: num, allocated: allocated, fd: fd, flags: flags };
    return ptr;
  },

  munmap__deps: ['msync'],
  munmap: function(start, num) {
    if (!_mmap.mappings) _mmap.mappings = {};
    // TODO: support unmmap'ing parts of allocations
    var info = _mmap.mappings[start];
    if (!info) return 0;
    if (num == info.num) {
      // At the Linux man page, it says:
      // "The file may not actually be updated until msync(2) or munmap(2) are called."
      // I guess that means we need to call msync when doing munmap
      _msync(start, num); // todo: which flags?

      FS.munmap(FS.getStream(info.fd));

      _mmap.mappings[start] = null;
      if (info.allocated) {
        _free(info.malloc);
      }
    }
    return 0;
  },

  // TODO: Implement mremap.

  mprotect: function(addr, len, prot) {
    // int mprotect(void *addr, size_t len, int prot);
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/mprotect.html
    // Pretend to succeed
    return 0;
  },

  msync: function(addr, len, flags) {
    // int msync(void *addr, size_t len, int flags);
    // http://pubs.opengroup.org/onlinepubs/009696799/functions/msync.html
    // TODO: support sync'ing parts of allocations
    var info = _mmap.mappings[addr];
    if (!info) return 0;
    if (len == info.num) {
      var buffer = new Uint8Array(HEAPU8.buffer, addr, len);
      return FS.msync(FS.getStream(info.fd), buffer, 0, len, info.flags);
    }

    return 0;
  },

  // ==========================================================================
  // stdlib.h
  // ==========================================================================

  // tiny, fake malloc/free implementation. If the program actually uses malloc,
  // a compiled version will be used; this will only be used if the runtime
  // needs to allocate something, for which this is good enough if otherwise
  // no malloc is needed.
  malloc: function(bytes) {
    /* Over-allocate to make sure it is byte-aligned by 8.
     * This will leak memory, but this is only the dummy
     * implementation (replaced by dlmalloc normally) so
     * not an issue.
     */
#if ASSERTIONS == 2
    Runtime.warnOnce('using stub malloc (reference it from C to have the real one included)');
#endif
    var ptr = Runtime.dynamicAlloc(bytes + 8);
    return (ptr+8) & 0xFFFFFFF8;
  },
  free: function() {
#if ASSERTIONS == 2
    Runtime.warnOnce('using stub free (reference it from C to have the real one included)');
#endif
},

  calloc: function(n, s) {
    var ret = _malloc(n*s);
    _memset(ret, 0, n*s);
    return ret;
  },

  abs: 'Math_abs',
  labs: 'Math_abs',
  llabs__deps: [function() { Types.preciseI64MathUsed = 1 }],
  llabs: function(lo, hi) {
    i64Math.abs(lo, hi);
    {{{ makeStructuralReturn([makeGetTempDouble(0, 'i32'), makeGetTempDouble(1, 'i32')]) }}};
  },

  exit__deps: ['_exit'],
  exit: function(status) {
    __exit(status);
  },

  _ZSt9terminatev__deps: ['exit'],
  _ZSt9terminatev: function() {
    _exit(-1234);
  },

  atexit: function(func, arg) {
    __ATEXIT__.unshift({ func: func, arg: arg });
  },
  __cxa_atexit: 'atexit',

  abort: function() {
    Module['abort']();
  },

  realloc__deps: ['memcpy'],
  realloc: function(ptr, size) {
    // Very simple, inefficient implementation - if you use a real malloc, best to use
    // a real realloc with it
    if (!size) {
      if (ptr) _free(ptr);
      return 0;
    }
    var ret = _malloc(size);
    if (ptr) {
      _memcpy(ret, ptr, size); // might be some invalid reads
      _free(ptr);
    }
    return ret;
  },

  _parseInt__deps: ['isspace', '__setErrNo', '$ERRNO_CODES'],
  _parseInt: function(str, endptr, base, min, max, bits, unsign) {
    // Skip space.
    while (_isspace({{{ makeGetValue('str', 0, 'i8') }}})) str++;

    // Check for a plus/minus sign.
    var multiplier = 1;
    if ({{{ makeGetValue('str', 0, 'i8') }}} == {{{ charCode('-') }}}) {
      multiplier = -1;
      str++;
    } else if ({{{ makeGetValue('str', 0, 'i8') }}} == {{{ charCode('+') }}}) {
      str++;
    }

    // Find base.
    var finalBase = base;
    if (!finalBase) {
      if ({{{ makeGetValue('str', 0, 'i8') }}} == {{{ charCode('0') }}}) {
        if ({{{ makeGetValue('str+1', 0, 'i8') }}} == {{{ charCode('x') }}} ||
            {{{ makeGetValue('str+1', 0, 'i8') }}} == {{{ charCode('X') }}}) {
          finalBase = 16;
          str += 2;
        } else {
          finalBase = 8;
          str++;
        }
      }
    } else if (finalBase==16) {
      if ({{{ makeGetValue('str', 0, 'i8') }}} == {{{ charCode('0') }}}) {
        if ({{{ makeGetValue('str+1', 0, 'i8') }}} == {{{ charCode('x') }}} ||
            {{{ makeGetValue('str+1', 0, 'i8') }}} == {{{ charCode('X') }}}) {
          str += 2;
        }
      }
    }
    if (!finalBase) finalBase = 10;

    // Get digits.
    var chr;
    var ret = 0;
    while ((chr = {{{ makeGetValue('str', 0, 'i8') }}}) != 0) {
      var digit = parseInt(String.fromCharCode(chr), finalBase);
      if (isNaN(digit)) {
        break;
      } else {
        ret = ret * finalBase + digit;
        str++;
      }
    }

    // Apply sign.
    ret *= multiplier;

    // Set end pointer.
    if (endptr) {
      {{{ makeSetValue('endptr', 0, 'str', '*') }}};
    }

    // Unsign if needed.
    if (unsign) {
      if (Math.abs(ret) > max) {
        ret = max;
        ___setErrNo(ERRNO_CODES.ERANGE);
      } else {
        ret = unSign(ret, bits);
      }
    }

    // Validate range.
    if (ret > max || ret < min) {
      ret = ret > max ? max : min;
      ___setErrNo(ERRNO_CODES.ERANGE);
    }

    if (bits == 64) {
      {{{ makeStructuralReturn(splitI64('ret')) }}};
    }

    return ret;
  },
  _parseInt64__deps: ['isspace', '__setErrNo', '$ERRNO_CODES', function() { Types.preciseI64MathUsed = 1 }],
  _parseInt64: function(str, endptr, base, min, max, unsign) {
    var isNegative = false;
    // Skip space.
    while (_isspace({{{ makeGetValue('str', 0, 'i8') }}})) str++;

    // Check for a plus/minus sign.
    if ({{{ makeGetValue('str', 0, 'i8') }}} == {{{ charCode('-') }}}) {
      str++;
      isNegative = true;
    } else if ({{{ makeGetValue('str', 0, 'i8') }}} == {{{ charCode('+') }}}) {
      str++;
    }

    // Find base.
    var ok = false;
    var finalBase = base;
    if (!finalBase) {
      if ({{{ makeGetValue('str', 0, 'i8') }}} == {{{ charCode('0') }}}) {
        if ({{{ makeGetValue('str+1', 0, 'i8') }}} == {{{ charCode('x') }}} ||
            {{{ makeGetValue('str+1', 0, 'i8') }}} == {{{ charCode('X') }}}) {
          finalBase = 16;
          str += 2;
        } else {
          finalBase = 8;
          ok = true; // we saw an initial zero, perhaps the entire thing is just "0"
        }
      }
    } else if (finalBase==16) {
      if ({{{ makeGetValue('str', 0, 'i8') }}} == {{{ charCode('0') }}}) {
        if ({{{ makeGetValue('str+1', 0, 'i8') }}} == {{{ charCode('x') }}} ||
            {{{ makeGetValue('str+1', 0, 'i8') }}} == {{{ charCode('X') }}}) {
          str += 2;
        }
      }
    }
    if (!finalBase) finalBase = 10;
    var start = str;

    // Get digits.
    var chr;
    while ((chr = {{{ makeGetValue('str', 0, 'i8') }}}) != 0) {
      var digit = parseInt(String.fromCharCode(chr), finalBase);
      if (isNaN(digit)) {
        break;
      } else {
        str++;
        ok = true;
      }
    }

    if (!ok) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      {{{ makeStructuralReturn(['0', '0']) }}};
    }

    // Set end pointer.
    if (endptr) {
      {{{ makeSetValue('endptr', 0, 'str', '*') }}};
    }

    try {
      var numberString = isNegative ? '-'+Pointer_stringify(start, str - start) : Pointer_stringify(start, str - start);
      i64Math.fromString(numberString, finalBase, min, max, unsign);
    } catch(e) {
      ___setErrNo(ERRNO_CODES.ERANGE); // not quite correct
    }

    {{{ makeStructuralReturn([makeGetTempDouble(0, 'i32'), makeGetTempDouble(1, 'i32')]) }}};
  },
  environ__deps: ['$ENV'],
  environ: 'allocate(1, "i32*", ALLOC_STATIC)',
  __environ__deps: ['environ'],
  __environ: 'environ',
  __buildEnvironment__deps: ['__environ'],
  __buildEnvironment: function(env) {
    // WARNING: Arbitrary limit!
    var MAX_ENV_VALUES = 64;
    var TOTAL_ENV_SIZE = 1024;

    // Statically allocate memory for the environment.
    var poolPtr;
    var envPtr;
    if (!___buildEnvironment.called) {
      ___buildEnvironment.called = true;
      // Set default values. Use string keys for Closure Compiler compatibility.
      ENV['USER'] = 'web_user';
      ENV['PATH'] = '/';
      ENV['PWD'] = '/';
      ENV['HOME'] = '/home/web_user';
      ENV['LANG'] = 'C';
      ENV['_'] = Module['thisProgram'];
      // Allocate memory.
      poolPtr = allocate(TOTAL_ENV_SIZE, 'i8', ALLOC_STATIC);
      envPtr = allocate(MAX_ENV_VALUES * {{{ Runtime.QUANTUM_SIZE }}},
                        'i8*', ALLOC_STATIC);
      {{{ makeSetValue('envPtr', '0', 'poolPtr', 'i8*') }}};
      {{{ makeSetValue(makeGlobalUse('_environ'), 0, 'envPtr', 'i8*') }}};
    } else {
      envPtr = {{{ makeGetValue(makeGlobalUse('_environ'), '0', 'i8**') }}};
      poolPtr = {{{ makeGetValue('envPtr', '0', 'i8*') }}};
    }

    // Collect key=value lines.
    var strings = [];
    var totalSize = 0;
    for (var key in env) {
      if (typeof env[key] === 'string') {
        var line = key + '=' + env[key];
        strings.push(line);
        totalSize += line.length;
      }
    }
    if (totalSize > TOTAL_ENV_SIZE) {
      throw new Error('Environment size exceeded TOTAL_ENV_SIZE!');
    }

    // Make new.
    var ptrSize = {{{ Runtime.getNativeTypeSize('i8*') }}};
    for (var i = 0; i < strings.length; i++) {
      var line = strings[i];
      writeAsciiToMemory(line, poolPtr);
      {{{ makeSetValue('envPtr', 'i * ptrSize', 'poolPtr', 'i8*') }}};
      poolPtr += line.length + 1;
    }
    {{{ makeSetValue('envPtr', 'strings.length * ptrSize', '0', 'i8*') }}};
  },
  $ENV__deps: ['__buildEnvironment'],
  $ENV__postset: '___buildEnvironment(ENV);',
  $ENV: {},
  getenv__deps: ['$ENV'],
  getenv: function(name) {
    // char *getenv(const char *name);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/getenv.html
    if (name === 0) return 0;
    name = Pointer_stringify(name);
    if (!ENV.hasOwnProperty(name)) return 0;

    if (_getenv.ret) _free(_getenv.ret);
    _getenv.ret = allocate(intArrayFromString(ENV[name]), 'i8', ALLOC_NORMAL);
    return _getenv.ret;
  },
  clearenv__deps: ['$ENV', '__buildEnvironment'],
  clearenv: function(name) {
    // int clearenv (void);
    // http://www.gnu.org/s/hello/manual/libc/Environment-Access.html#index-clearenv-3107
    ENV = {};
    ___buildEnvironment(ENV);
    return 0;
  },
  setenv__deps: ['$ENV', '__buildEnvironment', '$ERRNO_CODES', '__setErrNo'],
  setenv: function(envname, envval, overwrite) {
    // int setenv(const char *envname, const char *envval, int overwrite);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/setenv.html
    if (envname === 0) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    }
    var name = Pointer_stringify(envname);
    var val = Pointer_stringify(envval);
    if (name === '' || name.indexOf('=') !== -1) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    }
    if (ENV.hasOwnProperty(name) && !overwrite) return 0;
    ENV[name] = val;
    ___buildEnvironment(ENV);
    return 0;
  },
  unsetenv__deps: ['$ENV', '__buildEnvironment', '$ERRNO_CODES', '__setErrNo'],
  unsetenv: function(name) {
    // int unsetenv(const char *name);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/unsetenv.html
    if (name === 0) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    }
    name = Pointer_stringify(name);
    if (name === '' || name.indexOf('=') !== -1) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    }
    if (ENV.hasOwnProperty(name)) {
      delete ENV[name];
      ___buildEnvironment(ENV);
    }
    return 0;
  },
  putenv__deps: ['$ENV', '__buildEnvironment', '$ERRNO_CODES', '__setErrNo'],
  putenv: function(string) {
    // int putenv(char *string);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/putenv.html
    // WARNING: According to the standard (and the glibc implementation), the
    //          string is taken by reference so future changes are reflected.
    //          We copy it instead, possibly breaking some uses.
    if (string === 0) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    }
    string = Pointer_stringify(string);
    var splitPoint = string.indexOf('=')
    if (string === '' || string.indexOf('=') === -1) {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    }
    var name = string.slice(0, splitPoint);
    var value = string.slice(splitPoint + 1);
    if (!(name in ENV) || ENV[name] !== value) {
      ENV[name] = value;
      ___buildEnvironment(ENV);
    }
    return 0;
  },

  getloadavg: function(loadavg, nelem) {
    // int getloadavg(double loadavg[], int nelem);
    // http://linux.die.net/man/3/getloadavg
    var limit = Math.min(nelem, 3);
    var doubleSize = {{{ Runtime.getNativeTypeSize('double') }}};
    for (var i = 0; i < limit; i++) {
      {{{ makeSetValue('loadavg', 'i * doubleSize', '0.1', 'double') }}};
    }
    return limit;
  },

  realpath__deps: ['$FS', '__setErrNo'],
  realpath: function(file_name, resolved_name) {
    // char *realpath(const char *restrict file_name, char *restrict resolved_name);
    // http://pubs.opengroup.org/onlinepubs/009604499/functions/realpath.html
    var absolute = FS.analyzePath(Pointer_stringify(file_name));
    if (absolute.error) {
      ___setErrNo(absolute.error);
      return 0;
    } else {
      var size = Math.min(4095, absolute.path.length);  // PATH_MAX - 1.
      if (resolved_name === 0) resolved_name = _malloc(size+1);
      for (var i = 0; i < size; i++) {
        {{{ makeSetValue('resolved_name', 'i', 'absolute.path.charCodeAt(i)', 'i8') }}};
      }
      {{{ makeSetValue('resolved_name', 'size', '0', 'i8') }}};
      return resolved_name;
    }
  },

  // For compatibility, call to rand() when code requests arc4random(), although this is *not* at all
  // as strong as rc4 is. See https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man3/arc4random.3.html
  arc4random: 'rand',

  // ==========================================================================
  // string.h
  // ==========================================================================

  memcpy__inline: function(dest, src, num, align) {
    var ret = '';
    ret += makeCopyValues(dest, src, num, 'null', null, align);
    return ret;
  },

  emscripten_memcpy_big: function(dest, src, num) {
    HEAPU8.set(HEAPU8.subarray(src, src+num), dest);
    return dest;
  },

  memcpy__asm: true,
  memcpy__sig: 'iiii',
  memcpy__deps: ['emscripten_memcpy_big'],
  memcpy: function(dest, src, num) {
    dest = dest|0; src = src|0; num = num|0;
    var ret = 0;
    if ((num|0) >= 4096) return _emscripten_memcpy_big(dest|0, src|0, num|0)|0;
    ret = dest|0;
    if ((dest&3) == (src&3)) {
      while (dest & 3) {
        if ((num|0) == 0) return ret|0;
        {{{ makeSetValueAsm('dest', 0, makeGetValueAsm('src', 0, 'i8'), 'i8') }}};
        dest = (dest+1)|0;
        src = (src+1)|0;
        num = (num-1)|0;
      }
      while ((num|0) >= 4) {
        {{{ makeSetValueAsm('dest', 0, makeGetValueAsm('src', 0, 'i32'), 'i32') }}};
        dest = (dest+4)|0;
        src = (src+4)|0;
        num = (num-4)|0;
      }
    }
    while ((num|0) > 0) {
      {{{ makeSetValueAsm('dest', 0, makeGetValueAsm('src', 0, 'i8'), 'i8') }}};
      dest = (dest+1)|0;
      src = (src+1)|0;
      num = (num-1)|0;
    }
    return ret|0;
  },

  llvm_memcpy_i32: 'memcpy',
  llvm_memcpy_i64: 'memcpy',
  llvm_memcpy_p0i8_p0i8_i32: 'memcpy',
  llvm_memcpy_p0i8_p0i8_i64: 'memcpy',

  memmove__sig: 'iiii',
  memmove__asm: true,
  memmove__deps: ['memcpy'],
  memmove: function(dest, src, num) {
    dest = dest|0; src = src|0; num = num|0;
    var ret = 0;
    if (((src|0) < (dest|0)) & ((dest|0) < ((src + num)|0))) {
      // Unlikely case: Copy backwards in a safe manner
      ret = dest;
      src = (src + num)|0;
      dest = (dest + num)|0;
      while ((num|0) > 0) {
        dest = (dest - 1)|0;
        src = (src - 1)|0;
        num = (num - 1)|0;
        {{{ makeSetValueAsm('dest', 0, makeGetValueAsm('src', 0, 'i8'), 'i8') }}};
      }
      dest = ret;
    } else {
      _memcpy(dest, src, num) | 0;
    }
    return dest | 0;
  },
  llvm_memmove_i32: 'memmove',
  llvm_memmove_i64: 'memmove',
  llvm_memmove_p0i8_p0i8_i32: 'memmove',
  llvm_memmove_p0i8_p0i8_i64: 'memmove',

  memset__inline: function(ptr, value, num, align) {
    return makeSetValues(ptr, 0, value, 'null', num, align);
  },
  memset__sig: 'iiii',
  memset__asm: true,
  memset: function(ptr, value, num) {
    ptr = ptr|0; value = value|0; num = num|0;
    var stop = 0, value4 = 0, stop4 = 0, unaligned = 0;
    stop = (ptr + num)|0;
    if ((num|0) >= {{{ Math.round(2.5*UNROLL_LOOP_MAX) }}}) {
      // This is unaligned, but quite large, so work hard to get to aligned settings
      value = value & 0xff;
      unaligned = ptr & 3;
      value4 = value | (value << 8) | (value << 16) | (value << 24);
      stop4 = stop & ~3;
      if (unaligned) {
        unaligned = (ptr + 4 - unaligned)|0;
        while ((ptr|0) < (unaligned|0)) { // no need to check for stop, since we have large num
          {{{ makeSetValueAsm('ptr', 0, 'value', 'i8') }}};
          ptr = (ptr+1)|0;
        }
      }
      while ((ptr|0) < (stop4|0)) {
        {{{ makeSetValueAsm('ptr', 0, 'value4', 'i32') }}};
        ptr = (ptr+4)|0;
      }
    }
    while ((ptr|0) < (stop|0)) {
      {{{ makeSetValueAsm('ptr', 0, 'value', 'i8') }}};
      ptr = (ptr+1)|0;
    }
    return (ptr-num)|0;
  },
  llvm_memset_i32: 'memset',
  llvm_memset_p0i8_i32: 'memset',
  llvm_memset_p0i8_i64: 'memset',

  strlen__sig: 'ii',
  strlen__asm: true,
  strlen: function(ptr) {
    ptr = ptr|0;
    var curr = 0;
    curr = ptr;
    while ({{{ makeGetValueAsm('curr', '0', 'i8') }}}) {
      curr = (curr + 1)|0;
    }
    return (curr - ptr)|0;
  },

  strcpy__asm: true,
  strcpy__sig: 'iii',
  strcpy: function(pdest, psrc) {
    pdest = pdest|0; psrc = psrc|0;
    var i = 0;
    do {
      {{{ makeCopyValues('(pdest+i)|0', '(psrc+i)|0', 1, 'i8', null, 1) }}};
      i = (i+1)|0;
    } while ({{{ makeGetValueAsm('psrc', 'i-1', 'i8') }}});
    return pdest|0;
  },

  strncpy__asm: true,
  strncpy__sig: 'iiii',
  strncpy: function(pdest, psrc, num) {
    pdest = pdest|0; psrc = psrc|0; num = num|0;
    var padding = 0, curr = 0, i = 0;
    while ((i|0) < (num|0)) {
      curr = padding ? 0 : {{{ makeGetValueAsm('psrc', 'i', 'i8') }}};
      {{{ makeSetValue('pdest', 'i', 'curr', 'i8') }}};
      padding = padding ? 1 : ({{{ makeGetValueAsm('psrc', 'i', 'i8') }}} == 0);
      i = (i+1)|0;
    }
    return pdest|0;
  },

  strcat__asm: true,
  strcat__sig: 'iii',
  strcat__deps: ['strlen'],
  strcat: function(pdest, psrc) {
    pdest = pdest|0; psrc = psrc|0;
    var i = 0;
    var pdestEnd = 0;
    pdestEnd = (pdest + (_strlen(pdest)|0))|0;
    do {
      {{{ makeCopyValues('pdestEnd+i', 'psrc+i', 1, 'i8', null, 1) }}};
      i = (i+1)|0;
    } while ({{{ makeGetValueAsm('psrc', 'i-1', 'i8') }}});
    return pdest|0;
  },

  strerror_r__deps: ['$ERRNO_CODES', '$ERRNO_MESSAGES', '__setErrNo'],
  strerror_r: function(errnum, strerrbuf, buflen) {
    if (errnum in ERRNO_MESSAGES) {
      if (ERRNO_MESSAGES[errnum].length > buflen - 1) {
        return ___setErrNo(ERRNO_CODES.ERANGE);
      } else {
        var msg = ERRNO_MESSAGES[errnum];
        writeAsciiToMemory(msg, strerrbuf);
        return 0;
      }
    } else {
      return ___setErrNo(ERRNO_CODES.EINVAL);
    }
  },
  strerror__deps: ['strerror_r'],
  strerror: function(errnum) {
    if (!_strerror.buffer) _strerror.buffer = _malloc(256);
    _strerror_r(errnum, _strerror.buffer, 256);
    return _strerror.buffer;
  },

  // ==========================================================================
  // ctype.h
  // ==========================================================================

  // Lookup tables for glibc ctype implementation.
  __ctype_b_loc: function() {
    // http://refspecs.freestandards.org/LSB_3.0.0/LSB-Core-generic/LSB-Core-generic/baselib---ctype-b-loc.html
    var me = ___ctype_b_loc;
    if (!me.ret) {
      var values = [
        0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
        0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
        0,0,0,0,0,0,0,0,0,0,2,2,2,2,2,2,2,2,2,8195,8194,8194,8194,8194,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,24577,49156,49156,49156,
        49156,49156,49156,49156,49156,49156,49156,49156,49156,49156,49156,49156,55304,55304,55304,55304,55304,55304,55304,55304,
        55304,55304,49156,49156,49156,49156,49156,49156,49156,54536,54536,54536,54536,54536,54536,50440,50440,50440,50440,50440,
        50440,50440,50440,50440,50440,50440,50440,50440,50440,50440,50440,50440,50440,50440,50440,49156,49156,49156,49156,49156,
        49156,54792,54792,54792,54792,54792,54792,50696,50696,50696,50696,50696,50696,50696,50696,50696,50696,50696,50696,50696,
        50696,50696,50696,50696,50696,50696,50696,49156,49156,49156,49156,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
        0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
        0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
      ];
      var i16size = {{{ Runtime.getNativeTypeSize('i16') }}};
      var arr = _malloc(values.length * i16size);
      for (var i = 0; i < values.length; i++) {
        {{{ makeSetValue('arr', 'i * i16size', 'values[i]', 'i16') }}};
      }
      me.ret = allocate([arr + 128 * i16size], 'i16*', ALLOC_NORMAL);
    }
    return me.ret;
  },
  __ctype_tolower_loc: function() {
    // http://refspecs.freestandards.org/LSB_3.1.1/LSB-Core-generic/LSB-Core-generic/libutil---ctype-tolower-loc.html
    var me = ___ctype_tolower_loc;
    if (!me.ret) {
      var values = [
        128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,
        158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,
        188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,
        218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,
        248,249,250,251,252,253,254,-1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,
        33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,97,98,99,100,101,102,103,
        104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,91,92,93,94,95,96,97,98,99,100,101,102,103,
        104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,
        134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,
        164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,
        194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,
        224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,
        254,255
      ];
      var i32size = {{{ Runtime.getNativeTypeSize('i32') }}};
      var arr = _malloc(values.length * i32size);
      for (var i = 0; i < values.length; i++) {
        {{{ makeSetValue('arr', 'i * i32size', 'values[i]', 'i32') }}};
      }
      me.ret = allocate([arr + 128 * i32size], 'i32*', ALLOC_NORMAL);
    }
    return me.ret;
  },
  __ctype_toupper_loc: function() {
    // http://refspecs.freestandards.org/LSB_3.1.1/LSB-Core-generic/LSB-Core-generic/libutil---ctype-toupper-loc.html
    var me = ___ctype_toupper_loc;
    if (!me.ret) {
      var values = [
        128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,
        158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,
        188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,
        218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,
        248,249,250,251,252,253,254,-1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,
        33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,
        73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,
        81,82,83,84,85,86,87,88,89,90,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,
        145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,
        175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,
        205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,
        235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255
      ];
      var i32size = {{{ Runtime.getNativeTypeSize('i32') }}};
      var arr = _malloc(values.length * i32size);
      for (var i = 0; i < values.length; i++) {
        {{{ makeSetValue('arr', 'i * i32size', 'values[i]', 'i32') }}};
      }
      me.ret = allocate([arr + 128 * i32size], 'i32*', ALLOC_NORMAL);
    }
    return me.ret;
  },

  // ==========================================================================
  // GCC/LLVM specifics
  // ==========================================================================
  __builtin_prefetch: function(){},

  // ==========================================================================
  // LLVM specifics
  // ==========================================================================

  llvm_va_start__inline: function(ptr) {
    // varargs - we received a pointer to the varargs as a final 'extra' parameter called 'varrp'
    // 2-word structure: struct { void* start; void* currentOffset; }
    return makeSetValue(ptr, 0, 'varrp', 'void*') + ';' + makeSetValue(ptr, Runtime.QUANTUM_SIZE, 0, 'void*');
  },

  llvm_va_end: function() {},

  llvm_va_copy: function(ppdest, ppsrc) {
    // copy the list start
    {{{ makeCopyValues('ppdest', 'ppsrc', Runtime.QUANTUM_SIZE, 'null', null, 1) }}};
    
    // copy the list's current offset (will be advanced with each call to va_arg)
    {{{ makeCopyValues('(ppdest+'+Runtime.QUANTUM_SIZE+')', '(ppsrc+'+Runtime.QUANTUM_SIZE+')', Runtime.QUANTUM_SIZE, 'null', null, 1) }}};
  },

  llvm_bswap_i16__asm: true,
  llvm_bswap_i16__sig: 'ii',
  llvm_bswap_i16: function(x) {
    x = x|0;
    return (((x&0xff)<<8) | ((x>>8)&0xff))|0;
  },

  llvm_bswap_i32__asm: true,
  llvm_bswap_i32__sig: 'ii',
  llvm_bswap_i32: function(x) {
    x = x|0;
    return (((x&0xff)<<24) | (((x>>8)&0xff)<<16) | (((x>>16)&0xff)<<8) | (x>>>24))|0;
  },

  llvm_bswap_i64__deps: ['llvm_bswap_i32'],
  llvm_bswap_i64: function(l, h) {
    var retl = _llvm_bswap_i32(h)>>>0;
    var reth = _llvm_bswap_i32(l)>>>0;
    {{{ makeStructuralReturn(['retl', 'reth']) }}};
  },

  llvm_ctlz_i64__asm: true,
  llvm_ctlz_i64__sig: 'iii',
  llvm_ctlz_i64: function(l, h, isZeroUndef) {
    l = l | 0;
    h = h | 0;
    isZeroUndef = isZeroUndef | 0;
    var ret = 0;
    ret = Math_clz32(h) | 0;
    if ((ret | 0) == 32) ret = ret + (Math_clz32(l) | 0) | 0;
    {{{ makeSetTempRet0('0') }}};
    return ret | 0;
  },

  llvm_cttz_i32__deps: [function() {
    function cttz(x) {
      for (var i = 0; i < 8; i++) {
        if (x & (1 << i)) {
          return i;
        }
      }
      return 8;
    }
    if (SIDE_MODULE) return ''; // uses it from the parent
    return 'var cttz_i8 = allocate([' + range(256).map(function(x) { return cttz(x) }).join(',') + '], "i8", ALLOC_STATIC);';
  }],
  llvm_cttz_i32__asm: true,
  llvm_cttz_i32__sig: 'ii',
  llvm_cttz_i32: function(x) {
    x = x|0;
    var ret = 0;
    ret = {{{ makeGetValueAsm('cttz_i8', 'x & 0xff', 'i8') }}};
    if ((ret|0) < 8) return ret|0;
    ret = {{{ makeGetValueAsm('cttz_i8', '(x >> 8)&0xff', 'i8') }}};
    if ((ret|0) < 8) return (ret + 8)|0;
    ret = {{{ makeGetValueAsm('cttz_i8', '(x >> 16)&0xff', 'i8') }}};
    if ((ret|0) < 8) return (ret + 16)|0;
    return ({{{ makeGetValueAsm('cttz_i8', 'x >>> 24', 'i8') }}} + 24)|0;
  },

  llvm_cttz_i64__deps: ['llvm_cttz_i32'],
  llvm_cttz_i64: function(l, h) {
    var ret = _llvm_cttz_i32(l);
    if (ret == 32) ret += _llvm_cttz_i32(h);
    {{{ makeStructuralReturn(['ret', '0']) }}};
  },

  llvm_ctpop_i32: function(x) {
    var ret = 0;
    while (x) {
      if (x&1) ret++;
      x >>>= 1;
    }
    return ret;
  },

  llvm_ctpop_i64__deps: ['llvm_ctpop_i32'],
  llvm_ctpop_i64: function(l, h) {
    return _llvm_ctpop_i32(l) + _llvm_ctpop_i32(h);
  },

  llvm_trap: function() {
    abort('trap!');
  },

  llvm_prefetch: function(){},

  __assert_fail: function(condition, filename, line, func) {
    ABORT = true;
    throw 'Assertion failed: ' + Pointer_stringify(condition) + ', at: ' + [filename ? Pointer_stringify(filename) : 'unknown filename', line, func ? Pointer_stringify(func) : 'unknown function'] + ' at ' + stackTrace();
  },

  __assert_func: function(filename, line, func, condition) {
    throw 'Assertion failed: ' + (condition ? Pointer_stringify(condition) : 'unknown condition') + ', at: ' + [filename ? Pointer_stringify(filename) : 'unknown filename', line, func ? Pointer_stringify(func) : 'unknown function'] + ' at ' + stackTrace();
  },

  __cxa_guard_acquire: function(variable) {
    if (!{{{ makeGetValue(0, 'variable', 'i8', null, null, 1) }}}) { // ignore SAFE_HEAP stuff because llvm mixes i64 and i8 here
      {{{ makeSetValue(0, 'variable', '1', 'i8') }}};
      return 1;
    }
    return 0;
  },
  __cxa_guard_release: function() {},
  __cxa_guard_abort: function() {},

  $EXCEPTIONS: {
    last: 0,
    caught: [],
    infos: {},
    deAdjust: function(adjusted) {
      if (!adjusted || EXCEPTIONS.infos[adjusted]) return adjusted;
      for (var ptr in EXCEPTIONS.infos) {
        var info = EXCEPTIONS.infos[ptr];
        if (info.adjusted === adjusted) {
#if EXCEPTION_DEBUG
          Module.printErr('de-adjusted exception ptr ' + adjusted + ' to ' + ptr);
#endif
          return ptr;
        }
      }
#if EXCEPTION_DEBUG
      Module.printErr('no de-adjustment for unknown exception ptr ' + adjusted);
#endif
      return adjusted;
    },
    addRef: function(ptr) {
#if EXCEPTION_DEBUG
      Module.printErr('addref ' + ptr);
#endif
      if (!ptr) return;
      var info = EXCEPTIONS.infos[ptr];
      info.refcount++;
    },
    decRef: function(ptr) {
#if EXCEPTION_DEBUG
      Module.printErr('decref ' + ptr);
#endif
      if (!ptr) return;
      var info = EXCEPTIONS.infos[ptr];
      assert(info.refcount > 0);
      info.refcount--;
      if (info.refcount === 0) {
        if (info.destructor) {
          Runtime.dynCall('vi', info.destructor, [ptr]);
        }
        delete EXCEPTIONS.infos[ptr];
        ___cxa_free_exception(ptr);
#if EXCEPTION_DEBUG
        Module.printErr('decref freeing exception ' + [ptr, EXCEPTIONS.last, 'stack', EXCEPTIONS.caught]);
#endif
      }
    },
    clearRef: function(ptr) {
      if (!ptr) return;
      var info = EXCEPTIONS.infos[ptr];
      info.refcount = 0;
    },
  },

  // Exceptions
  __cxa_allocate_exception__deps: ['malloc'],
  __cxa_allocate_exception: function(size) {
    return _malloc(size);
  },
  __cxa_free_exception__deps: ['free'],
  __cxa_free_exception: function(ptr) {
    try {
      return _free(ptr);
    } catch(e) { // XXX FIXME
#if ASSERTIONS
      Module.printErr('exception during cxa_free_exception: ' + e);
#endif
    }
  },
  __cxa_increment_exception_refcount__deps: ['$EXCEPTIONS'],
  __cxa_increment_exception_refcount: function(ptr) {
    EXCEPTIONS.addRef(EXCEPTIONS.deAdjust(ptr));
  },
  __cxa_decrement_exception_refcount__deps: ['$EXCEPTIONS'],
  __cxa_decrement_exception_refcount: function(ptr) {
    EXCEPTIONS.decRef(EXCEPTIONS.deAdjust(ptr));
  },
  // Here, we throw an exception after recording a couple of values that we need to remember
  // We also remember that it was the last exception thrown as we need to know that later.
  __cxa_throw__sig: 'viii',
  __cxa_throw__deps: ['_ZSt18uncaught_exceptionv', '__cxa_find_matching_catch', '$EXCEPTIONS'],
  __cxa_throw: function(ptr, type, destructor) {
#if EXCEPTION_DEBUG
    Module.printErr('Compiled code throwing an exception, ' + [ptr,type,destructor]);
#endif
    EXCEPTIONS.infos[ptr] = {
      ptr: ptr,
      adjusted: ptr,
      type: type,
      destructor: destructor,
      refcount: 0
    };
    EXCEPTIONS.last = ptr;
    if (!("uncaught_exception" in __ZSt18uncaught_exceptionv)) {
      __ZSt18uncaught_exceptionv.uncaught_exception = 1;
    } else {
      __ZSt18uncaught_exceptionv.uncaught_exception++;
    }
    {{{ makeThrow('ptr') }}}
  },
  // This exception will be caught twice, but while begin_catch runs twice,
  // we early-exit from end_catch when the exception has been rethrown, so
  // pop that here from the caught exceptions.
  __cxa_rethrow__deps: ['__cxa_end_catch', '$EXCEPTIONS'],
  __cxa_rethrow: function() {
    ___cxa_end_catch.rethrown = true;
    var ptr = EXCEPTIONS.caught.pop();
#if EXCEPTION_DEBUG
    Module.printErr('Compiled code RE-throwing an exception, popped ' + [ptr, EXCEPTIONS.last, 'stack', EXCEPTIONS.caught]);
#endif
    EXCEPTIONS.last = ptr;
    {{{ makeThrow('ptr') }}}
  },
  llvm_eh_exception__deps: ['$EXCEPTIONS'],
  llvm_eh_exception: function() {
    return EXCEPTIONS.last;
  },
  llvm_eh_selector__jsargs: true,
  llvm_eh_selector__deps: ['$EXCEPTIONS'],
  llvm_eh_selector: function(unused_exception_value, personality/*, varargs*/) {
    var type = EXCEPTIONS.last;
    for (var i = 2; i < arguments.length; i++) {
      if (arguments[i] ==  type) return type;
    }
    return 0;
  },
  llvm_eh_typeid_for: function(type) {
    return type;
  },
  __cxa_begin_catch__deps: ['_ZSt18uncaught_exceptionv', '$EXCEPTIONS'],
  __cxa_begin_catch: function(ptr) {
    __ZSt18uncaught_exceptionv.uncaught_exception--;
    EXCEPTIONS.caught.push(ptr);
#if EXCEPTION_DEBUG
		Module.printErr('cxa_begin_catch ' + [ptr, 'stack', EXCEPTIONS.caught]);
#endif
    EXCEPTIONS.addRef(EXCEPTIONS.deAdjust(ptr));
    return ptr;
  },
  // We're done with a catch. Now, we can run the destructor if there is one
  // and free the exception. Note that if the dynCall on the destructor fails
  // due to calling apply on undefined, that means that the destructor is
  // an invalid index into the FUNCTION_TABLE, so something has gone wrong.
  __cxa_end_catch__deps: ['__cxa_free_exception', '$EXCEPTIONS'],
  __cxa_end_catch: function() {
    if (___cxa_end_catch.rethrown) {
      ___cxa_end_catch.rethrown = false;
      return;
    }
    // Clear state flag.
    asm['setThrew'](0);
    // Call destructor if one is registered then clear it.
    var ptr = EXCEPTIONS.caught.pop();
#if EXCEPTION_DEBUG
    Module.printErr('cxa_end_catch popped ' + [ptr, EXCEPTIONS.last, 'stack', EXCEPTIONS.caught]);
#endif
    if (ptr) {
      EXCEPTIONS.decRef(EXCEPTIONS.deAdjust(ptr));
      EXCEPTIONS.last = 0; // XXX in decRef?
    }
  },
  __cxa_get_exception_ptr: function(ptr) {
#if EXCEPTION_DEBUG
    Module.printErr('cxa_get_exception_ptr ' + ptr);
#endif
    // TODO: use info.adjusted?
    return ptr;
  },
  _ZSt18uncaught_exceptionv: function() { // std::uncaught_exception()
    return !!__ZSt18uncaught_exceptionv.uncaught_exception;
  },
  __cxa_uncaught_exception__deps: ['_ZSt18uncaught_exceptionv'],
  __cxa_uncaught_exception: function() {
    return !!__ZSt18uncaught_exceptionv.uncaught_exception;
  },

  __cxa_call_unexpected: function(exception) {
    Module.printErr('Unexpected exception thrown, this is not properly supported - aborting');
    ABORT = true;
    throw exception;
  },

  __cxa_current_primary_exception: function() {
    var ret = EXCEPTIONS.caught[EXCEPTIONS.caught.length-1] || 0;
    if (ret) EXCEPTIONS.addRef(EXCEPTIONS.deAdjust(ret));
    return ret;
  },

  __cxa_rethrow_primary_exception__deps: ['__cxa_rethrow'],
  __cxa_rethrow_primary_exception: function(ptr) {
    if (!ptr) return;
    EXCEPTIONS.caught.push(ptr);
    ___cxa_rethrow();
  },

  terminate: '__cxa_call_unexpected',

  __gxx_personality_v0__deps: ['_ZSt18uncaught_exceptionv', '__cxa_find_matching_catch'],
  __gxx_personality_v0: function() {
  },

  // Finds a suitable catch clause for when an exception is thrown.
  // In normal compilers, this functionality is handled by the C++
  // 'personality' routine. This is passed a fairly complex structure
  // relating to the context of the exception and makes judgements
  // about how to handle it. Some of it is about matching a suitable
  // catch clause, and some of it is about unwinding. We already handle
  // unwinding using 'if' blocks around each function, so the remaining
  // functionality boils down to picking a suitable 'catch' block.
  // We'll do that here, instead, to keep things simpler.

  __cxa_find_matching_catch__deps: ['__resumeException', '$EXCEPTIONS'],
  __cxa_find_matching_catch: function() {
    var thrown = EXCEPTIONS.last;
    if (!thrown) {
      // just pass through the null ptr
      {{{ makeStructuralReturn([0, 0]) }}};
    }
    var info = EXCEPTIONS.infos[thrown];
    var throwntype = info.type;
    if (!throwntype) {
      // just pass through the thrown ptr
      {{{ makeStructuralReturn(['thrown', 0]) }}};
    }
    var typeArray = Array.prototype.slice.call(arguments);

    var pointer = Module['___cxa_is_pointer_type'](throwntype);
    // can_catch receives a **, add indirection
    if (!___cxa_find_matching_catch.buffer) ___cxa_find_matching_catch.buffer = _malloc(4);
#if EXCEPTION_DEBUG
    Module.print("can_catch on " + [thrown]);
#endif
    {{{ makeSetValue('___cxa_find_matching_catch.buffer', '0', 'thrown', '*') }}};
    thrown = ___cxa_find_matching_catch.buffer;
    // The different catch blocks are denoted by different types.
    // Due to inheritance, those types may not precisely match the
    // type of the thrown object. Find one which matches, and
    // return the type of the catch block which should be called.
    for (var i = 0; i < typeArray.length; i++) {
      if (typeArray[i] && Module['___cxa_can_catch'](typeArray[i], throwntype, thrown)) {
        thrown = {{{ makeGetValue('thrown', '0', '*') }}}; // undo indirection
        info.adjusted = thrown;
#if EXCEPTION_DEBUG
        Module.print("  can_catch found " + [thrown, typeArray[i]]);
#endif
        {{{ makeStructuralReturn(['thrown', 'typeArray[i]']) }}};
      }
    }
    // Shouldn't happen unless we have bogus data in typeArray
    // or encounter a type for which emscripten doesn't have suitable
    // typeinfo defined. Best-efforts match just in case.
    thrown = {{{ makeGetValue('thrown', '0', '*') }}}; // undo indirection
    {{{ makeStructuralReturn(['thrown', 'throwntype']) }}};
  },

  __resumeException__deps: ['$EXCEPTIONS', function() { Functions.libraryFunctions['___resumeException'] = 1 }], // will be called directly from compiled code
  __resumeException: function(ptr) {
#if EXCEPTION_DEBUG
    Module.print("Resuming exception " + [ptr, EXCEPTIONS.last]);
#endif
    if (!EXCEPTIONS.last) { EXCEPTIONS.last = ptr; }
    EXCEPTIONS.clearRef(EXCEPTIONS.deAdjust(ptr)); // exception refcount should be cleared, but don't free it
    {{{ makeThrow('ptr') }}}
  },

  llvm_uadd_with_overflow_i8: function(x, y) {
    x = x & 0xff;
    y = y & 0xff;
    {{{ makeStructuralReturn(['(x+y) & 0xff', 'x+y > 255']) }}};
  },

  llvm_umul_with_overflow_i8: function(x, y) {
    x = x & 0xff;
    y = y & 0xff;
    {{{ makeStructuralReturn(['(x*y) & 0xff', 'x*y > 255']) }}};
  },

  llvm_uadd_with_overflow_i16: function(x, y) {
    x = x & 0xffff;
    y = y & 0xffff;
    {{{ makeStructuralReturn(['(x+y) & 0xffff', 'x+y > 65535']) }}};
  },

  llvm_umul_with_overflow_i16: function(x, y) {
    x = x & 0xffff;
    y = y & 0xffff;
    {{{ makeStructuralReturn(['(x*y) & 0xffff', 'x*y > 65535']) }}};
  },

  llvm_uadd_with_overflow_i32: function(x, y) {
    x = x>>>0;
    y = y>>>0;
    {{{ makeStructuralReturn(['(x+y)>>>0', 'x+y > 4294967295']) }}};
  },

  llvm_umul_with_overflow_i32: function(x, y) {
    x = x>>>0;
    y = y>>>0;
    {{{ makeStructuralReturn(['(x*y)>>>0', 'x*y > 4294967295']) }}};
  },

  llvm_umul_with_overflow_i64__deps: [function() { Types.preciseI64MathUsed = 1 }],
  llvm_umul_with_overflow_i64: function(xl, xh, yl, yh) {
#if ASSERTIONS
    Runtime.warnOnce('no overflow support in llvm_umul_with_overflow_i64');
#endif
    var low = ___muldi3(xl, xh, yl, yh);
    {{{ makeStructuralReturn(['low', makeGetTempRet0(), '0']) }}};
  },

  llvm_stacksave: function() {
    var self = _llvm_stacksave;
    if (!self.LLVM_SAVEDSTACKS) {
      self.LLVM_SAVEDSTACKS = [];
    }
    self.LLVM_SAVEDSTACKS.push(Runtime.stackSave());
    return self.LLVM_SAVEDSTACKS.length-1;
  },
  llvm_stackrestore: function(p) {
    var self = _llvm_stacksave;
    var ret = self.LLVM_SAVEDSTACKS[p];
    self.LLVM_SAVEDSTACKS.splice(p, 1);
    Runtime.stackRestore(ret);
  },

  __cxa_pure_virtual: function() {
    ABORT = true;
    throw 'Pure virtual function called!';
  },

  llvm_flt_rounds: function() {
    return -1; // 'indeterminable' for FLT_ROUNDS
  },

  llvm_memory_barrier: function(){},

  llvm_atomic_load_add_i32_p0i32: function(ptr, delta) {
    var ret = {{{ makeGetValue('ptr', '0', 'i32') }}};
    {{{ makeSetValue('ptr', '0', 'ret+delta', 'i32') }}};
    return ret;
  },

  llvm_expect_i32__inline: function(val, expected) {
    return '(' + val + ')';
  },

  llvm_lifetime_start: function() {},
  llvm_lifetime_end: function() {},

  llvm_invariant_start: function() {},
  llvm_invariant_end: function() {},

  llvm_objectsize_i32: function() { return -1 }, // TODO: support this

  llvm_dbg_declare__inline: function() { throw 'llvm_debug_declare' }, // avoid warning

  // llvm-nacl

  llvm_nacl_atomic_store_i32__inline: true,

  llvm_nacl_atomic_cmpxchg_i8__inline: true,
  llvm_nacl_atomic_cmpxchg_i16__inline: true,
  llvm_nacl_atomic_cmpxchg_i32__inline: true,

  // gnu atomics

  __atomic_is_lock_free: function(size, ptr) {
    return size <= 4 && (ptr&(size-1)) == 0;
  },

  __atomic_load_8: function(ptr, memmodel) {
    {{{ makeStructuralReturn([makeGetValue('ptr', 0, 'i32'), makeGetValue('ptr', 4, 'i32')]) }}};
  },

  __atomic_store_8: function(ptr, vall, valh, memmodel) {
    {{{ makeSetValue('ptr', 0, 'vall', 'i32') }}};
    {{{ makeSetValue('ptr', 4, 'valh', 'i32') }}};
  },

  __atomic_exchange_8: function(ptr, vall, valh, memmodel) {
    var l = {{{ makeGetValue('ptr', 0, 'i32') }}};
    var h = {{{ makeGetValue('ptr', 4, 'i32') }}};
    {{{ makeSetValue('ptr', 0, 'vall', 'i32') }}};
    {{{ makeSetValue('ptr', 4, 'valh', 'i32') }}};
    {{{ makeStructuralReturn(['l', 'h']) }}};
  },

  __atomic_compare_exchange_8: function(ptr, expected, desiredl, desiredh, weak, success_memmodel, failure_memmodel) {
    var pl = {{{ makeGetValue('ptr', 0, 'i32') }}};
    var ph = {{{ makeGetValue('ptr', 4, 'i32') }}};
    var el = {{{ makeGetValue('expected', 0, 'i32') }}};
    var eh = {{{ makeGetValue('expected', 4, 'i32') }}};
    if (pl === el && ph === eh) {
      {{{ makeSetValue('ptr', 0, 'desiredl', 'i32') }}};
      {{{ makeSetValue('ptr', 4, 'desiredh', 'i32') }}};
      return 1;
    } else {
      {{{ makeSetValue('expected', 0, 'pl', 'i32') }}};
      {{{ makeSetValue('expected', 4, 'ph', 'i32') }}};
      return 0;
    }
  },

  __atomic_fetch_add_8__deps: ['llvm_uadd_with_overflow_i64'],
  __atomic_fetch_add_8: function(ptr, vall, valh, memmodel) {
    var l = {{{ makeGetValue('ptr', 0, 'i32') }}};
    var h = {{{ makeGetValue('ptr', 4, 'i32') }}};
    {{{ makeSetValue('ptr', 0, '_llvm_uadd_with_overflow_i64(l, h, vall, valh)', 'i32') }}};
    {{{ makeSetValue('ptr', 4, makeGetTempRet0(), 'i32') }}};
    {{{ makeStructuralReturn(['l', 'h']) }}};
  },

  __atomic_fetch_sub_8__deps: ['i64Subtract'],
  __atomic_fetch_sub_8: function(ptr, vall, valh, memmodel) {
    var l = {{{ makeGetValue('ptr', 0, 'i32') }}};
    var h = {{{ makeGetValue('ptr', 4, 'i32') }}};
    {{{ makeSetValue('ptr', 0, '_i64Subtract(l, h, vall, valh)', 'i32') }}};
    {{{ makeSetValue('ptr', 4, makeGetTempRet0(), 'i32') }}};
    {{{ makeStructuralReturn(['l', 'h']) }}};
  },

  __atomic_fetch_and_8__deps: ['i64Subtract'],
  __atomic_fetch_and_8: function(ptr, vall, valh, memmodel) {
    var l = {{{ makeGetValue('ptr', 0, 'i32') }}};
    var h = {{{ makeGetValue('ptr', 4, 'i32') }}};
    {{{ makeSetValue('ptr', 0, 'l&vall', 'i32') }}};
    {{{ makeSetValue('ptr', 4, 'h&valh', 'i32') }}};
    {{{ makeStructuralReturn(['l', 'h']) }}};
  },

  __atomic_fetch_or_8: function(ptr, vall, valh, memmodel) {
    var l = {{{ makeGetValue('ptr', 0, 'i32') }}};
    var h = {{{ makeGetValue('ptr', 4, 'i32') }}};
    {{{ makeSetValue('ptr', 0, 'l|vall', 'i32') }}};
    {{{ makeSetValue('ptr', 4, 'h|valh', 'i32') }}};
    {{{ makeStructuralReturn(['l', 'h']) }}};
  },

  __atomic_fetch_xor_8: function(ptr, vall, valh, memmodel) {
    var l = {{{ makeGetValue('ptr', 0, 'i32') }}};
    var h = {{{ makeGetValue('ptr', 4, 'i32') }}};
    {{{ makeSetValue('ptr', 0, 'l^vall', 'i32') }}};
    {{{ makeSetValue('ptr', 4, 'h^valh', 'i32') }}};
    {{{ makeStructuralReturn(['l', 'h']) }}};
  },


  // ==========================================================================
  // llvm-mono integration
  // ==========================================================================

  llvm_mono_load_i8_p0i8: function(ptr) {
    return {{{ makeGetValue('ptr', 0, 'i8') }}};
  },

  llvm_mono_store_i8_p0i8: function(value, ptr) {
    {{{ makeSetValue('ptr', 0, 'value', 'i8') }}};
  },

  llvm_mono_load_i16_p0i16: function(ptr) {
    return {{{ makeGetValue('ptr', 0, 'i16') }}};
  },

  llvm_mono_store_i16_p0i16: function(value, ptr) {
    {{{ makeSetValue('ptr', 0, 'value', 'i16') }}};
  },

  llvm_mono_load_i32_p0i32: function(ptr) {
    return {{{ makeGetValue('ptr', 0, 'i32') }}};
  },

  llvm_mono_store_i32_p0i32: function(value, ptr) {
    {{{ makeSetValue('ptr', 0, 'value', 'i32') }}};
  },

  // ==========================================================================
  // math.h
  // ==========================================================================

  cos: 'Math_cos',
  cosf: 'Math_cos',
  cosl: 'Math_cos',
  sin: 'Math_sin',
  sinf: 'Math_sin',
  sinl: 'Math_sin',
  tan: 'Math_tan',
  tanf: 'Math_tan',
  tanl: 'Math_tan',
  acos: 'Math_acos',
  acosf: 'Math_acos',
  acosl: 'Math_acos',
  asin: 'Math_asin',
  asinf: 'Math_asin',
  asinl: 'Math_asin',
  atan: 'Math_atan',
  atanf: 'Math_atan',
  atanl: 'Math_atan',
  atan2: 'Math_atan2',
  atan2f: 'Math_atan2',
  atan2l: 'Math_atan2',
  exp: 'Math_exp',
  expf: 'Math_exp',
  expl: 'Math_exp',

  // The erf and erfc functions are inspired from
  // http://www.digitalmars.com/archives/cplusplus/3634.html
  // and mruby source code at
  // https://github.com/mruby/mruby/blob/master/src/math.c
  erfc: function(x) {
    var MATH_TOLERANCE = 1E-12;
    var ONE_SQRTPI = 0.564189583547756287;
    var a = 1;
    var b = x;
    var c = x;
    var d = x * x + 0.5;
    var n = 1.0;
    var q2 = b / d;
    var q1, t;

    if (Math.abs(x) < 2.2) {
      return 1.0 - _erf(x);
    }
    if (x < 0) {
      return 2.0 - _erfc(-x);
    }
    do {
      t = a * n + b * x;
      a = b;
      b = t;
      t = c * n + d * x;
      c = d;
      d = t;
      n += 0.5;
      q1 = q2;
      q2 = b / d;
    } while (Math.abs(q1 - q2) / q2 > MATH_TOLERANCE);
    return (ONE_SQRTPI * Math.exp(- x * x) * q2);
  },
  erfcf: 'erfc',
  erfcl: 'erfc',
  erf__deps: ['erfc'],
  erf: function(x) {
    var MATH_TOLERANCE = 1E-12;
    var TWO_SQRTPI = 1.128379167095512574;
    var sum = x;
    var term = x;
    var xsqr = x*x;
    var j = 1;

    if (Math.abs(x) > 2.2) {
      return 1.0 - _erfc(x);
    }
    do {
      term *= xsqr / j;
      sum -= term / (2 * j + 1);
      ++j;
      term *= xsqr / j;
      sum += term / (2 * j + 1);
      ++j;
    } while (Math.abs(term / sum) > MATH_TOLERANCE);
    return (TWO_SQRTPI * sum);
  },
  erff: 'erf',
  erfl: 'erf',
  log: 'Math_log',
  logf: 'Math_log',
  logl: 'Math_log',
  sqrt: 'Math_sqrt',
  sqrtf: 'Math_sqrt',
  sqrtl: 'Math_sqrt',
  fabs: 'Math_abs',
  fabsf: 'Math_abs',
  fabsl: 'Math_abs',
  llvm_fabs_f32: 'Math_abs',
  llvm_fabs_f64: 'Math_abs',
  ceil: 'Math_ceil',
  ceilf: 'Math_ceil',
  ceill: 'Math_ceil',
  floor: 'Math_floor',
  floorf: 'Math_floor',
  floorl: 'Math_floor',
  pow: 'Math_pow',
  powf: 'Math_pow',
  powl: 'Math_pow',
  llvm_sqrt_f32: 'Math_sqrt',
  llvm_sqrt_f64: 'Math_sqrt',
  llvm_pow_f32: 'Math_pow',
  llvm_pow_f64: 'Math_pow',
  llvm_log_f32: 'Math_log',
  llvm_log_f64: 'Math_log',
  llvm_exp_f32: 'Math_exp',
  llvm_exp_f64: 'Math_exp',

  _reallyNegative: function(x) {
    return x < 0 || (x === 0 && (1/x) === -Infinity);
  },

  div: function(divt, numer, denom) {
    var quot = (numer / denom) | 0;
    var rem = numer - quot * denom;
    {{{ makeSetValue('divt', C_STRUCTS.div_t.quot, 'quot', 'i32') }}};
    {{{ makeSetValue('divt', C_STRUCTS.div_t.rem, 'rem', 'i32') }}};
    return divt;
  },

  // ==========================================================================
  // sys/utsname.h
  // ==========================================================================

  uname: function(name) {
    // int uname(struct utsname *name);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/uname.html
    var layout = {{{ JSON.stringify(C_STRUCTS.utsname) }}};
    function copyString(element, value) {
      var offset = layout[element];
      writeAsciiToMemory(value, name + offset);
    }
    if (name === 0) {
      return -1;
    } else {
      copyString('sysname', 'Emscripten');
      copyString('nodename', 'emscripten');
      copyString('release', '1.0');
      copyString('version', '#1');
      copyString('machine', 'x86-JS');
      return 0;
    }
  },

  // ==========================================================================
  // dlfcn.h - Dynamic library loading
  //
  // Some limitations:
  //
  //  * Minification on each file separately may not work, as they will
  //    have different shortened names. You can in theory combine them, then
  //    minify, then split... perhaps.
  //
  //  * LLVM optimizations may fail. If the child wants to access a function
  //    in the parent, LLVM opts may remove it from the parent when it is
  //    being compiled. Not sure how to tell LLVM to not do so.
  // ==========================================================================

  $DLFCN: {
    error: null,
    errorMsg: null,
    loadedLibs: {}, // handle -> [refcount, name, lib_object]
    loadedLibNames: {}, // name -> handle
  },
  // void* dlopen(const char* filename, int flag);
  dlopen__deps: ['$DLFCN', '$FS', '$ENV'],
  dlopen: function(filename, flag) {
    // void *dlopen(const char *file, int mode);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/dlopen.html
    filename = filename === 0 ? '__self__' : (ENV['LD_LIBRARY_PATH'] || '/') + Pointer_stringify(filename);

    if (DLFCN.loadedLibNames[filename]) {
      // Already loaded; increment ref count and return.
      var handle = DLFCN.loadedLibNames[filename];
      DLFCN.loadedLibs[handle].refcount++;
      return handle;
    }

    if (filename === '__self__') {
      var handle = -1;
      var lib_module = Module;
      var cached_functions = {};
    } else {
      var target = FS.findObject(filename);
      if (!target || target.isFolder || target.isDevice) {
        DLFCN.errorMsg = 'Could not find dynamic lib: ' + filename;
        return 0;
      } else {
        FS.forceLoadFile(target);
        var lib_data = FS.readFile(filename, { encoding: 'utf8' });
      }

      try {
        var lib_module = eval(lib_data)(
          Runtime.alignFunctionTables(),
          Module
        );
      } catch (e) {
#if ASSERTIONS
        Module.printErr('Error in loading dynamic library: ' + e);
#endif
        DLFCN.errorMsg = 'Could not evaluate dynamic lib: ' + filename;
        return 0;
      }

      // Not all browsers support Object.keys().
      var handle = 1;
      for (var key in DLFCN.loadedLibs) {
        if (DLFCN.loadedLibs.hasOwnProperty(key)) handle++;
      }

      // We don't care about RTLD_NOW and RTLD_LAZY.
      if (flag & 256) { // RTLD_GLOBAL
        for (var ident in lib_module) {
          if (lib_module.hasOwnProperty(ident)) {
            Module[ident] = lib_module[ident];
          }
        }
      }

      var cached_functions = {};
    }
    DLFCN.loadedLibs[handle] = {
      refcount: 1,
      name: filename,
      module: lib_module,
      cached_functions: cached_functions
    };
    DLFCN.loadedLibNames[filename] = handle;

    return handle;
  },
  // int dlclose(void* handle);
  dlclose__deps: ['$DLFCN'],
  dlclose: function(handle) {
    // int dlclose(void *handle);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/dlclose.html
    if (!DLFCN.loadedLibs[handle]) {
      DLFCN.errorMsg = 'Tried to dlclose() unopened handle: ' + handle;
      return 1;
    } else {
      var lib_record = DLFCN.loadedLibs[handle];
      if (--lib_record.refcount == 0) {
        if (lib_record.module.cleanups) {
          lib_record.module.cleanups.forEach(function(cleanup) { cleanup() });
        }
        delete DLFCN.loadedLibNames[lib_record.name];
        delete DLFCN.loadedLibs[handle];
      }
      return 0;
    }
  },
  // void* dlsym(void* handle, const char* symbol);
  dlsym__deps: ['$DLFCN'],
  dlsym: function(handle, symbol) {
    // void *dlsym(void *restrict handle, const char *restrict name);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/dlsym.html
    symbol = Pointer_stringify(symbol);

    if (!DLFCN.loadedLibs[handle]) {
      DLFCN.errorMsg = 'Tried to dlsym() from an unopened handle: ' + handle;
      return 0;
    } else {
      var lib = DLFCN.loadedLibs[handle];
      symbol = '_' + symbol;
      if (lib.cached_functions.hasOwnProperty(symbol)) {
        return lib.cached_functions[symbol];
      }
      if (!lib.module.hasOwnProperty(symbol)) {
        DLFCN.errorMsg = ('Tried to lookup unknown symbol "' + symbol +
                               '" in dynamic lib: ' + lib.name);
        return 0;
      } else {
        var result = lib.module[symbol];
        if (typeof result == 'function') {
          result = Runtime.addFunction(result);
          lib.cached_functions = result;
        }
        return result;
      }
    }
  },
  // char* dlerror(void);
  dlerror__deps: ['$DLFCN'],
  dlerror: function() {
    // char *dlerror(void);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/dlerror.html
    if (DLFCN.errorMsg === null) {
      return 0;
    } else {
      if (DLFCN.error) _free(DLFCN.error);
      var msgArr = intArrayFromString(DLFCN.errorMsg);
      DLFCN.error = allocate(msgArr, 'i8', ALLOC_NORMAL);
      DLFCN.errorMsg = null;
      return DLFCN.error;
    }
  },

  dladdr: function(addr, info) {
    // report all function pointers as coming from this program itself XXX not really correct in any way
    var fname = allocate(intArrayFromString(Module['thisProgram'] || './this.program'), 'i8', ALLOC_NORMAL); // XXX leak
    {{{ makeSetValue('addr', 0, 'fname', 'i32') }}};
    {{{ makeSetValue('addr', QUANTUM_SIZE, '0', 'i32') }}};
    {{{ makeSetValue('addr', QUANTUM_SIZE*2, '0', 'i32') }}};
    {{{ makeSetValue('addr', QUANTUM_SIZE*3, '0', 'i32') }}};
    return 1;
  },

  // ==========================================================================
  // pwd.h
  // ==========================================================================

  // TODO: Implement.
  // http://pubs.opengroup.org/onlinepubs/009695399/basedefs/pwd.h.html
  getpwuid: function(uid) {
    return 0; // NULL
  },

  // ==========================================================================
  // termios.h
  // ==========================================================================
  tcgetattr: function(fildes, termios_p) {
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/tcgetattr.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    if (!stream.tty) {
      ___setErrNo(ERRNO_CODES.ENOTTY);
      return -1;
    }
    return 0;
  },

  tcsetattr: function(fildes, optional_actions, termios_p) {
    // http://pubs.opengroup.org/onlinepubs/7908799/xsh/tcsetattr.html
    var stream = FS.getStream(fildes);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    if (!stream.tty) {
      ___setErrNo(ERRNO_CODES.ENOTTY);
      return -1;
    }
    return 0;
  },

  cfgetospeed: function(termios_p) {
#if ASSERTIONS
    Runtime.warnOnce('cfgetospeed() returning a fake value');
#endif
    return 15;
  },

  // ==========================================================================
  // time.h
  // ==========================================================================

  clock: function() {
    if (_clock.start === undefined) _clock.start = Date.now();
    return ((Date.now() - _clock.start) * ({{{ cDefine('CLOCKS_PER_SEC') }}} / 1000))|0;
  },

  time: function(ptr) {
    var ret = (Date.now()/1000)|0;
    if (ptr) {
      {{{ makeSetValue('ptr', 0, 'ret', 'i32') }}};
    }
    return ret;
  },

  difftime: function(time1, time0) {
    return time1 - time0;
  },

  // Statically allocated time struct.
  __tm_current: 'allocate({{{ C_STRUCTS.tm.__size__ }}}, "i8", ALLOC_STATIC)',
  // Statically allocated copy of the string "GMT" for gmtime() to point to
  __tm_timezone: 'allocate(intArrayFromString("GMT"), "i8", ALLOC_STATIC)',
  // Statically allocated time strings.
  __tm_formatted: 'allocate({{{ C_STRUCTS.tm.__size__ }}}, "i8", ALLOC_STATIC)',

  mktime__deps: ['tzset'],
  mktime: function(tmPtr) {
    _tzset();
    var date = new Date({{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_year, 'i32') }}} + 1900,
                        {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_mon, 'i32') }}},
                        {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_mday, 'i32') }}},
                        {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_hour, 'i32') }}},
                        {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_min, 'i32') }}},
                        {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_sec, 'i32') }}},
                        0);

    // There's an ambiguous hour when the time goes back; the tm_isdst field is
    // used to disambiguate it.  Date() basically guesses, so we fix it up if it
    // guessed wrong, or fill in tm_isdst with the guess if it's -1.
    var dst = {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_isdst, 'i32') }}};
    var guessedOffset = date.getTimezoneOffset();
    var start = new Date(date.getFullYear(), 0, 1);
    var summerOffset = new Date(2000, 6, 1).getTimezoneOffset();
    var winterOffset = start.getTimezoneOffset();
    var dstOffset = Math.min(winterOffset, summerOffset); // DST is in December in South
    if (dst < 0) {
      {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_isdst, 'Number(winterOffset != guessedOffset)', 'i32') }}};
    } else if ((dst > 0) != (winterOffset != guessedOffset)) {
      var summerOffset = new Date(date.getFullYear(), 6, 1).getTimezoneOffset();
      var trueOffset = dst > 0 ? summerOffset : winterOffset;
      // Don't try setMinutes(date.getMinutes() + ...) -- it's messed up.
      date.setTime(date.getTime() + (trueOffset - guessedOffset)*60000);
    }

    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_wday, 'date.getDay()', 'i32') }}};
    var yday = ((date.getTime() - start.getTime()) / (1000 * 60 * 60 * 24))|0;
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_yday, 'yday', 'i32') }}};

    return (date.getTime() / 1000)|0;
  },
  timelocal: 'mktime',

  gmtime__deps: ['__tm_current', 'gmtime_r'],
  gmtime: function(time) {
    return _gmtime_r(time, ___tm_current);
  },

  gmtime_r__deps: ['__tm_timezone'],
  gmtime_r: function(time, tmPtr) {
    var date = new Date({{{ makeGetValue('time', 0, 'i32') }}}*1000);
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_sec, 'date.getUTCSeconds()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_min, 'date.getUTCMinutes()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_hour, 'date.getUTCHours()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_mday, 'date.getUTCDate()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_mon, 'date.getUTCMonth()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_year, 'date.getUTCFullYear()-1900', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_wday, 'date.getUTCDay()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_gmtoff, '0', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_isdst, '0', 'i32') }}};
    var start = Date.UTC(date.getUTCFullYear(), 0, 1, 0, 0, 0, 0);
    var yday = ((date.getTime() - start) / (1000 * 60 * 60 * 24))|0;
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_yday, 'yday', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_zone, '___tm_timezone', 'i32') }}};

    return tmPtr;
  },
  timegm__deps: ['tzset'],
  timegm: function(tmPtr) {
    _tzset();
    var time = Date.UTC({{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_year, 'i32') }}} + 1900,
                        {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_mon, 'i32') }}},
                        {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_mday, 'i32') }}},
                        {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_hour, 'i32') }}},
                        {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_min, 'i32') }}},
                        {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_sec, 'i32') }}},
                        0);
    var date = new Date(time);

    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_wday, 'date.getUTCDay()', 'i32') }}};
    var start = Date.UTC(date.getUTCFullYear(), 0, 1, 0, 0, 0, 0);
    var yday = ((date.getTime() - start) / (1000 * 60 * 60 * 24))|0;
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_yday, 'yday', 'i32') }}};

    return (date.getTime() / 1000)|0;
  },

  localtime__deps: ['__tm_current', 'localtime_r'],
  localtime: function(time) {
    return _localtime_r(time, ___tm_current);
  },

  localtime_r__deps: ['__tm_timezone', 'tzset'],
  localtime_r: function(time, tmPtr) {
    _tzset();
    var date = new Date({{{ makeGetValue('time', 0, 'i32') }}}*1000);
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_sec, 'date.getSeconds()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_min, 'date.getMinutes()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_hour, 'date.getHours()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_mday, 'date.getDate()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_mon, 'date.getMonth()', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_year, 'date.getFullYear()-1900', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_wday, 'date.getDay()', 'i32') }}};

    var start = new Date(date.getFullYear(), 0, 1);
    var yday = ((date.getTime() - start.getTime()) / (1000 * 60 * 60 * 24))|0;
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_yday, 'yday', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_gmtoff, '-(date.getTimezoneOffset() * 60)', 'i32') }}};

    // DST is in December in South
    var summerOffset = new Date(2000, 6, 1).getTimezoneOffset();
    var winterOffset = start.getTimezoneOffset();
    var dst = (date.getTimezoneOffset() == Math.min(winterOffset, summerOffset))|0;
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_isdst, 'dst', 'i32') }}};

    var zonePtr = {{{ makeGetValue(makeGlobalUse('_tzname'), 'dst ? Runtime.QUANTUM_SIZE : 0', 'i32') }}};
    {{{ makeSetValue('tmPtr', C_STRUCTS.tm.tm_zone, 'zonePtr', 'i32') }}};

    return tmPtr;
  },

  asctime__deps: ['__tm_formatted', 'asctime_r'],
  asctime: function(tmPtr) {
    return _asctime_r(tmPtr, ___tm_formatted);
  },

  asctime_r__deps: ['__tm_formatted', 'mktime'],
  asctime_r: function(tmPtr, buf) {
    var date = {
      tm_sec: {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_sec, 'i32') }}},
      tm_min: {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_min, 'i32') }}},
      tm_hour: {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_hour, 'i32') }}},
      tm_mday: {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_mday, 'i32') }}},
      tm_mon: {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_mon, 'i32') }}},
      tm_year: {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_year, 'i32') }}},
      tm_wday: {{{ makeGetValue('tmPtr', C_STRUCTS.tm.tm_wday, 'i32') }}}
    };
    var days = [ "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" ];
    var months = [ "Jan", "Feb", "Mar", "Apr", "May", "Jun",
                   "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" ];
    var s = days[date.tm_wday] + ' ' + months[date.tm_mon] +
        (date.tm_mday < 10 ? '  ' : ' ') + date.tm_mday +
        (date.tm_hour < 10 ? ' 0' : ' ') + date.tm_hour +
        (date.tm_min < 10 ? ':0' : ':') + date.tm_min +
        (date.tm_sec < 10 ? ':0' : ':') + date.tm_sec +
        ' ' + (1900 + date.tm_year) + "\n";
    writeStringToMemory(s, buf);
    return buf;
  },

  ctime__deps: ['__tm_current', 'ctime_r'],
  ctime: function(timer) {
    return _ctime_r(timer, ___tm_current);
  },

  ctime_r__deps: ['localtime_r', 'asctime_r'],
  ctime_r: function(time, buf) {
    var stack = Runtime.stackSave();
    var rv = _asctime_r(_localtime_r(time, Runtime.stackAlloc({{{ C_STRUCTS.tm.__size__ }}})), buf);
    Runtime.stackRestore(stack);
    return rv;
  },

  dysize: function(year) {
    var leap = ((year % 4 == 0) && ((year % 100 != 0) || (year % 400 == 0)));
    return leap ? 366 : 365;
  },

  // TODO: Initialize these to defaults on startup from system settings.
  // Note: glibc has one fewer underscore for all of these. Also used in other related functions (timegm)
  tzname: 'allocate({{{ 2*Runtime.QUANTUM_SIZE }}}, "i32*", ALLOC_STATIC)',
  daylight: 'allocate(1, "i32*", ALLOC_STATIC)',
  timezone: 'allocate(1, "i32*", ALLOC_STATIC)',
  tzset__deps: ['tzname', 'daylight', 'timezone'],
  tzset: function() {
    // TODO: Use (malleable) environment variables instead of system settings.
    if (_tzset.called) return;
    _tzset.called = true;

    {{{ makeSetValue(makeGlobalUse('_timezone'), '0', '-(new Date()).getTimezoneOffset() * 60', 'i32') }}};

    var winter = new Date(2000, 0, 1);
    var summer = new Date(2000, 6, 1);
    {{{ makeSetValue(makeGlobalUse('_daylight'), '0', 'Number(winter.getTimezoneOffset() != summer.getTimezoneOffset())', 'i32') }}};

    function extractZone(date) {
      var match = date.toTimeString().match(/\(([A-Za-z ]+)\)$/);
      return match ? match[1] : "GMT";
    };
    var winterName = extractZone(winter);
    var summerName = extractZone(summer);
    var winterNamePtr = allocate(intArrayFromString(winterName), 'i8', ALLOC_NORMAL);
    var summerNamePtr = allocate(intArrayFromString(summerName), 'i8', ALLOC_NORMAL);
    if (summer.getTimezoneOffset() < winter.getTimezoneOffset()) {
      // Northern hemisphere
      {{{ makeSetValue(makeGlobalUse('_tzname'), '0', 'winterNamePtr', 'i32') }}};
      {{{ makeSetValue(makeGlobalUse('_tzname'), Runtime.QUANTUM_SIZE, 'summerNamePtr', 'i32') }}};
    } else {
      {{{ makeSetValue(makeGlobalUse('_tzname'), '0', 'summerNamePtr', 'i32') }}};
      {{{ makeSetValue(makeGlobalUse('_tzname'), Runtime.QUANTUM_SIZE, 'winterNamePtr', 'i32') }}};
    }
  },

  stime__deps: ['$ERRNO_CODES', '__setErrNo'],
  stime: function(when) {
    ___setErrNo(ERRNO_CODES.EPERM);
    return -1;
  },

  _MONTH_DAYS_REGULAR: [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31],
  _MONTH_DAYS_LEAP: [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31],

  _isLeapYear: function(year) {
      return year%4 === 0 && (year%100 !== 0 || year%400 === 0);
  },

  _arraySum: function(array, index) {
    var sum = 0;
    for (var i = 0; i <= index; sum += array[i++]);
    return sum;
  },

  _addDays__deps: ['_isLeapYear', '_MONTH_DAYS_LEAP', '_MONTH_DAYS_REGULAR'],
  _addDays: function(date, days) {
    var newDate = new Date(date.getTime());
    while(days > 0) {
      var leap = __isLeapYear(newDate.getFullYear());
      var currentMonth = newDate.getMonth();
      var daysInCurrentMonth = (leap ? __MONTH_DAYS_LEAP : __MONTH_DAYS_REGULAR)[currentMonth];

      if (days > daysInCurrentMonth-newDate.getDate()) {
        // we spill over to next month
        days -= (daysInCurrentMonth-newDate.getDate()+1);
        newDate.setDate(1);
        if (currentMonth < 11) {
          newDate.setMonth(currentMonth+1)
        } else {
          newDate.setMonth(0);
          newDate.setFullYear(newDate.getFullYear()+1);
        }
      } else {
        // we stay in current month 
        newDate.setDate(newDate.getDate()+days);
        return newDate;
      }
    }

    return newDate;
  },

  strftime__deps: ['_isLeapYear', '_arraySum', '_addDays', '_MONTH_DAYS_REGULAR', '_MONTH_DAYS_LEAP'],
  strftime: function(s, maxsize, format, tm) {
    // size_t strftime(char *restrict s, size_t maxsize, const char *restrict format, const struct tm *restrict timeptr);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/strftime.html

    var tm_zone = {{{ makeGetValue('tm', C_STRUCTS.tm.tm_zone, 'i32') }}};

    var date = {
      tm_sec: {{{ makeGetValue('tm', C_STRUCTS.tm.tm_sec, 'i32') }}},
      tm_min: {{{ makeGetValue('tm', C_STRUCTS.tm.tm_min, 'i32') }}},
      tm_hour: {{{ makeGetValue('tm', C_STRUCTS.tm.tm_hour, 'i32') }}},
      tm_mday: {{{ makeGetValue('tm', C_STRUCTS.tm.tm_mday, 'i32') }}},
      tm_mon: {{{ makeGetValue('tm', C_STRUCTS.tm.tm_mon, 'i32') }}},
      tm_year: {{{ makeGetValue('tm', C_STRUCTS.tm.tm_year, 'i32') }}},
      tm_wday: {{{ makeGetValue('tm', C_STRUCTS.tm.tm_wday, 'i32') }}},
      tm_yday: {{{ makeGetValue('tm', C_STRUCTS.tm.tm_yday, 'i32') }}},
      tm_isdst: {{{ makeGetValue('tm', C_STRUCTS.tm.tm_isdst, 'i32') }}},
      tm_gmtoff: {{{ makeGetValue('tm', C_STRUCTS.tm.tm_gmtoff, 'i32') }}},
      tm_zone: tm_zone ? Pointer_stringify(tm_zone) : ''
    };

    var pattern = Pointer_stringify(format);

    // expand format
    var EXPANSION_RULES_1 = {
      '%c': '%a %b %d %H:%M:%S %Y',     // Replaced by the locale's appropriate date and time representation - e.g., Mon Aug  3 14:02:01 2013
      '%D': '%m/%d/%y',                 // Equivalent to %m / %d / %y
      '%F': '%Y-%m-%d',                 // Equivalent to %Y - %m - %d
      '%h': '%b',                       // Equivalent to %b
      '%r': '%I:%M:%S %p',              // Replaced by the time in a.m. and p.m. notation
      '%R': '%H:%M',                    // Replaced by the time in 24-hour notation
      '%T': '%H:%M:%S',                 // Replaced by the time
      '%x': '%m/%d/%y',                 // Replaced by the locale's appropriate date representation
      '%X': '%H:%M:%S'                  // Replaced by the locale's appropriate date representation
    };
    for (var rule in EXPANSION_RULES_1) {
      pattern = pattern.replace(new RegExp(rule, 'g'), EXPANSION_RULES_1[rule]);
    }

    var WEEKDAYS = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
    var MONTHS = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];

    function leadingSomething(value, digits, character) {
      var str = typeof value === 'number' ? value.toString() : (value || '');
      while (str.length < digits) {
        str = character[0]+str;
      }
      return str;
    };

    function leadingNulls(value, digits) {
      return leadingSomething(value, digits, '0');
    };

    function compareByDay(date1, date2) {
      function sgn(value) {
        return value < 0 ? -1 : (value > 0 ? 1 : 0);
      };

      var compare;
      if ((compare = sgn(date1.getFullYear()-date2.getFullYear())) === 0) {
        if ((compare = sgn(date1.getMonth()-date2.getMonth())) === 0) {
          compare = sgn(date1.getDate()-date2.getDate());
        }
      }
      return compare;
    };

    function getFirstWeekStartDate(janFourth) {
        switch (janFourth.getDay()) {
          case 0: // Sunday
            return new Date(janFourth.getFullYear()-1, 11, 29);
          case 1: // Monday
            return janFourth;
          case 2: // Tuesday
            return new Date(janFourth.getFullYear(), 0, 3);
          case 3: // Wednesday
            return new Date(janFourth.getFullYear(), 0, 2);
          case 4: // Thursday
            return new Date(janFourth.getFullYear(), 0, 1);
          case 5: // Friday
            return new Date(janFourth.getFullYear()-1, 11, 31);
          case 6: // Saturday
            return new Date(janFourth.getFullYear()-1, 11, 30);
        }
    };

    function getWeekBasedYear(date) {
        var thisDate = __addDays(new Date(date.tm_year+1900, 0, 1), date.tm_yday);

        var janFourthThisYear = new Date(thisDate.getFullYear(), 0, 4);
        var janFourthNextYear = new Date(thisDate.getFullYear()+1, 0, 4);

        var firstWeekStartThisYear = getFirstWeekStartDate(janFourthThisYear);
        var firstWeekStartNextYear = getFirstWeekStartDate(janFourthNextYear);

        if (compareByDay(firstWeekStartThisYear, thisDate) <= 0) {
          // this date is after the start of the first week of this year
          if (compareByDay(firstWeekStartNextYear, thisDate) <= 0) {
            return thisDate.getFullYear()+1;
          } else {
            return thisDate.getFullYear();
          }
        } else { 
          return thisDate.getFullYear()-1;
        }
    };

    var EXPANSION_RULES_2 = {
      '%a': function(date) {
        return WEEKDAYS[date.tm_wday].substring(0,3);
      },
      '%A': function(date) {
        return WEEKDAYS[date.tm_wday];
      },
      '%b': function(date) {
        return MONTHS[date.tm_mon].substring(0,3);
      },
      '%B': function(date) {
        return MONTHS[date.tm_mon];
      },
      '%C': function(date) {
        var year = date.tm_year+1900;
        return leadingNulls((year/100)|0,2);
      },
      '%d': function(date) {
        return leadingNulls(date.tm_mday, 2);
      },
      '%e': function(date) {
        return leadingSomething(date.tm_mday, 2, ' ');
      },
      '%g': function(date) {
        // %g, %G, and %V give values according to the ISO 8601:2000 standard week-based year. 
        // In this system, weeks begin on a Monday and week 1 of the year is the week that includes 
        // January 4th, which is also the week that includes the first Thursday of the year, and 
        // is also the first week that contains at least four days in the year. 
        // If the first Monday of January is the 2nd, 3rd, or 4th, the preceding days are part of 
        // the last week of the preceding year; thus, for Saturday 2nd January 1999, 
        // %G is replaced by 1998 and %V is replaced by 53. If December 29th, 30th, 
        // or 31st is a Monday, it and any following days are part of week 1 of the following year. 
        // Thus, for Tuesday 30th December 1997, %G is replaced by 1998 and %V is replaced by 01.
        
        return getWeekBasedYear(date).toString().substring(2);
      },
      '%G': function(date) {
        return getWeekBasedYear(date);
      },
      '%H': function(date) {
        return leadingNulls(date.tm_hour, 2);
      },
      '%I': function(date) {
        return leadingNulls(date.tm_hour < 13 ? date.tm_hour : date.tm_hour-12, 2);
      },
      '%j': function(date) {
        // Day of the year (001-366)
        return leadingNulls(date.tm_mday+__arraySum(__isLeapYear(date.tm_year+1900) ? __MONTH_DAYS_LEAP : __MONTH_DAYS_REGULAR, date.tm_mon-1), 3);
      },
      '%m': function(date) {
        return leadingNulls(date.tm_mon+1, 2);
      },
      '%M': function(date) {
        return leadingNulls(date.tm_min, 2);
      },
      '%n': function() {
        return '\n';
      },
      '%p': function(date) {
        if (date.tm_hour > 0 && date.tm_hour < 13) {
          return 'AM';
        } else {
          return 'PM';
        }
      },
      '%S': function(date) {
        return leadingNulls(date.tm_sec, 2);
      },
      '%t': function() {
        return '\t';
      },
      '%u': function(date) {
        var day = new Date(date.tm_year+1900, date.tm_mon+1, date.tm_mday, 0, 0, 0, 0);
        return day.getDay() || 7;
      },
      '%U': function(date) {
        // Replaced by the week number of the year as a decimal number [00,53]. 
        // The first Sunday of January is the first day of week 1; 
        // days in the new year before this are in week 0. [ tm_year, tm_wday, tm_yday]
        var janFirst = new Date(date.tm_year+1900, 0, 1);
        var firstSunday = janFirst.getDay() === 0 ? janFirst : __addDays(janFirst, 7-janFirst.getDay());
        var endDate = new Date(date.tm_year+1900, date.tm_mon, date.tm_mday);
        
        // is target date after the first Sunday?
        if (compareByDay(firstSunday, endDate) < 0) {
          // calculate difference in days between first Sunday and endDate
          var februaryFirstUntilEndMonth = __arraySum(__isLeapYear(endDate.getFullYear()) ? __MONTH_DAYS_LEAP : __MONTH_DAYS_REGULAR, endDate.getMonth()-1)-31;
          var firstSundayUntilEndJanuary = 31-firstSunday.getDate();
          var days = firstSundayUntilEndJanuary+februaryFirstUntilEndMonth+endDate.getDate();
          return leadingNulls(Math.ceil(days/7), 2);
        }

        return compareByDay(firstSunday, janFirst) === 0 ? '01': '00';
      },
      '%V': function(date) {
        // Replaced by the week number of the year (Monday as the first day of the week) 
        // as a decimal number [01,53]. If the week containing 1 January has four 
        // or more days in the new year, then it is considered week 1. 
        // Otherwise, it is the last week of the previous year, and the next week is week 1. 
        // Both January 4th and the first Thursday of January are always in week 1. [ tm_year, tm_wday, tm_yday]
        var janFourthThisYear = new Date(date.tm_year+1900, 0, 4);
        var janFourthNextYear = new Date(date.tm_year+1901, 0, 4);

        var firstWeekStartThisYear = getFirstWeekStartDate(janFourthThisYear);
        var firstWeekStartNextYear = getFirstWeekStartDate(janFourthNextYear);

        var endDate = __addDays(new Date(date.tm_year+1900, 0, 1), date.tm_yday);

        if (compareByDay(endDate, firstWeekStartThisYear) < 0) {
          // if given date is before this years first week, then it belongs to the 53rd week of last year
          return '53';
        } 

        if (compareByDay(firstWeekStartNextYear, endDate) <= 0) {
          // if given date is after next years first week, then it belongs to the 01th week of next year
          return '01';
        }

        // given date is in between CW 01..53 of this calendar year
        var daysDifference;
        if (firstWeekStartThisYear.getFullYear() < date.tm_year+1900) {
          // first CW of this year starts last year
          daysDifference = date.tm_yday+32-firstWeekStartThisYear.getDate()
        } else {
          // first CW of this year starts this year
          daysDifference = date.tm_yday+1-firstWeekStartThisYear.getDate();
        }
        return leadingNulls(Math.ceil(daysDifference/7), 2);
      },
      '%w': function(date) {
        var day = new Date(date.tm_year+1900, date.tm_mon+1, date.tm_mday, 0, 0, 0, 0);
        return day.getDay();
      },
      '%W': function(date) {
        // Replaced by the week number of the year as a decimal number [00,53]. 
        // The first Monday of January is the first day of week 1; 
        // days in the new year before this are in week 0. [ tm_year, tm_wday, tm_yday]
        var janFirst = new Date(date.tm_year, 0, 1);
        var firstMonday = janFirst.getDay() === 1 ? janFirst : __addDays(janFirst, janFirst.getDay() === 0 ? 1 : 7-janFirst.getDay()+1);
        var endDate = new Date(date.tm_year+1900, date.tm_mon, date.tm_mday);

        // is target date after the first Monday?
        if (compareByDay(firstMonday, endDate) < 0) {
          var februaryFirstUntilEndMonth = __arraySum(__isLeapYear(endDate.getFullYear()) ? __MONTH_DAYS_LEAP : __MONTH_DAYS_REGULAR, endDate.getMonth()-1)-31;
          var firstMondayUntilEndJanuary = 31-firstMonday.getDate();
          var days = firstMondayUntilEndJanuary+februaryFirstUntilEndMonth+endDate.getDate();
          return leadingNulls(Math.ceil(days/7), 2);
        }
        return compareByDay(firstMonday, janFirst) === 0 ? '01': '00';
      },
      '%y': function(date) {
        // Replaced by the last two digits of the year as a decimal number [00,99]. [ tm_year]
        return (date.tm_year+1900).toString().substring(2);
      },
      '%Y': function(date) {
        // Replaced by the year as a decimal number (for example, 1997). [ tm_year]
        return date.tm_year+1900;
      },
      '%z': function(date) {
        // Replaced by the offset from UTC in the ISO 8601:2000 standard format ( +hhmm or -hhmm ).
        // For example, "-0430" means 4 hours 30 minutes behind UTC (west of Greenwich).
        var off = date.tm_gmtoff;
        var ahead = off >= 0;
        off = Math.abs(off) / 60;
        // convert from minutes into hhmm format (which means 60 minutes = 100 units)
        off = (off / 60)*100 + (off % 60);
        return (ahead ? '+' : '-') + String("0000" + off).slice(-4);
      },
      '%Z': function(date) {
        return date.tm_zone;
      },
      '%%': function() {
        return '%';
      }
    };
    for (var rule in EXPANSION_RULES_2) {
      if (pattern.indexOf(rule) >= 0) {
        pattern = pattern.replace(new RegExp(rule, 'g'), EXPANSION_RULES_2[rule](date));
      }
    }

    var bytes = intArrayFromString(pattern, false);
    if (bytes.length > maxsize) {
      return 0;
    } 

    writeArrayToMemory(bytes, s);
    return bytes.length-1;
  },
  strftime_l__deps: ['strftime'],
  strftime_l: function(s, maxsize, format, tm) {
    return _strftime(s, maxsize, format, tm); // no locale support yet
  },

  strptime__deps: ['_isLeapYear', '_arraySum', '_addDays', '_MONTH_DAYS_REGULAR', '_MONTH_DAYS_LEAP'],
  strptime: function(buf, format, tm) {
    // char *strptime(const char *restrict buf, const char *restrict format, struct tm *restrict tm);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/strptime.html
    var pattern = Pointer_stringify(format);

    // escape special characters
    // TODO: not sure we really need to escape all of these in JS regexps
    var SPECIAL_CHARS = '\\!@#$^&*()+=-[]/{}|:<>?,.';
    for (var i=0, ii=SPECIAL_CHARS.length; i<ii; ++i) {
      pattern = pattern.replace(new RegExp('\\'+SPECIAL_CHARS[i], 'g'), '\\'+SPECIAL_CHARS[i]);
    }

    // reduce number of matchers
    var EQUIVALENT_MATCHERS = {
      '%A':  '%a',
      '%B':  '%b',
      '%c':  '%x\\s+%X',
      '%D':  '%m\\/%d\\/%y',
      '%e':  '%d',
      '%h':  '%b',
      '%R':  '%H\\:%M',
      '%r':  '%I\\:%M\\:%S\\s%p',
      '%T':  '%H\\:%M\\:%S',
      '%x':  '%m\\/%d\\/(?:%y|%Y)',
      '%X':  '%H\\:%M\\:%S'
    };
    for (var matcher in EQUIVALENT_MATCHERS) {
      pattern = pattern.replace(matcher, EQUIVALENT_MATCHERS[matcher]);
    }
    
    // TODO: take care of locale

    var DATE_PATTERNS = {
      /* weeday name */     '%a': '(?:Sun(?:day)?)|(?:Mon(?:day)?)|(?:Tue(?:sday)?)|(?:Wed(?:nesday)?)|(?:Thu(?:rsday)?)|(?:Fri(?:day)?)|(?:Sat(?:urday)?)',
      /* month name */      '%b': '(?:Jan(?:uary)?)|(?:Feb(?:ruary)?)|(?:Mar(?:ch)?)|(?:Apr(?:il)?)|May|(?:Jun(?:e)?)|(?:Jul(?:y)?)|(?:Aug(?:ust)?)|(?:Sep(?:tember)?)|(?:Oct(?:ober)?)|(?:Nov(?:ember)?)|(?:Dec(?:ember)?)',
      /* century */         '%C': '\\d\\d',
      /* day of month */    '%d': '0[1-9]|[1-9](?!\\d)|1\\d|2\\d|30|31',
      /* hour (24hr) */     '%H': '\\d(?!\\d)|[0,1]\\d|20|21|22|23',
      /* hour (12hr) */     '%I': '\\d(?!\\d)|0\\d|10|11|12',
      /* day of year */     '%j': '00[1-9]|0?[1-9](?!\\d)|0?[1-9]\\d(?!\\d)|[1,2]\\d\\d|3[0-6]\\d',
      /* month */           '%m': '0[1-9]|[1-9](?!\\d)|10|11|12',
      /* minutes */         '%M': '0\\d|\\d(?!\\d)|[1-5]\\d',
      /* whitespace */      '%n': '\\s',
      /* AM/PM */           '%p': 'AM|am|PM|pm|A\\.M\\.|a\\.m\\.|P\\.M\\.|p\\.m\\.',
      /* seconds */         '%S': '0\\d|\\d(?!\\d)|[1-5]\\d|60',
      /* week number */     '%U': '0\\d|\\d(?!\\d)|[1-4]\\d|50|51|52|53',
      /* week number */     '%W': '0\\d|\\d(?!\\d)|[1-4]\\d|50|51|52|53',
      /* weekday number */  '%w': '[0-6]',
      /* 2-digit year */    '%y': '\\d\\d',
      /* 4-digit year */    '%Y': '\\d\\d\\d\\d',
      /* % */               '%%': '%',
      /* whitespace */      '%t': '\\s',
    };

    var MONTH_NUMBERS = {JAN: 0, FEB: 1, MAR: 2, APR: 3, MAY: 4, JUN: 5, JUL: 6, AUG: 7, SEP: 8, OCT: 9, NOV: 10, DEC: 11};
    var DAY_NUMBERS_SUN_FIRST = {SUN: 0, MON: 1, TUE: 2, WED: 3, THU: 4, FRI: 5, SAT: 6};
    var DAY_NUMBERS_MON_FIRST = {MON: 0, TUE: 1, WED: 2, THU: 3, FRI: 4, SAT: 5, SUN: 6};

    for (var datePattern in DATE_PATTERNS) {
      pattern = pattern.replace(datePattern, '('+datePattern+DATE_PATTERNS[datePattern]+')');    
    }

    // take care of capturing groups
    var capture = [];
    for (var i=pattern.indexOf('%'); i>=0; i=pattern.indexOf('%')) {
      capture.push(pattern[i+1]);
      pattern = pattern.replace(new RegExp('\\%'+pattern[i+1], 'g'), '');
    }

    var matches = new RegExp('^'+pattern, "i").exec(Pointer_stringify(buf))
    // Module['print'](Pointer_stringify(buf)+ ' is matched by '+((new RegExp('^'+pattern)).source)+' into: '+JSON.stringify(matches));

    function initDate() {
      function fixup(value, min, max) {
        return (typeof value !== 'number' || isNaN(value)) ? min : (value>=min ? (value<=max ? value: max): min);
      };
      return {
        year: fixup({{{ makeGetValue('tm', C_STRUCTS.tm.tm_year, 'i32', 0, 0, 1) }}} + 1900 , 1970, 9999),
        month: fixup({{{ makeGetValue('tm', C_STRUCTS.tm.tm_mon, 'i32', 0, 0, 1) }}}, 0, 11),
        day: fixup({{{ makeGetValue('tm', C_STRUCTS.tm.tm_mday, 'i32', 0, 0, 1) }}}, 1, 31),
        hour: fixup({{{ makeGetValue('tm', C_STRUCTS.tm.tm_hour, 'i32', 0, 0, 1) }}}, 0, 23),
        min: fixup({{{ makeGetValue('tm', C_STRUCTS.tm.tm_min, 'i32', 0, 0, 1) }}}, 0, 59),
        sec: fixup({{{ makeGetValue('tm', C_STRUCTS.tm.tm_sec, 'i32', 0, 0, 1) }}}, 0, 59)
      };
    };

    if (matches) {
      var date = initDate();
      var value;

      function getMatch(symbol) {
        var pos = capture.indexOf(symbol);
        // check if symbol appears in regexp
        if (pos >= 0) {
          // return matched value or null (falsy!) for non-matches
          return matches[pos+1];
        }
        return;
      }

      // seconds
      if ((value=getMatch('S'))) {
        date.sec = parseInt(value);
      }

      // minutes
      if ((value=getMatch('M'))) {
        date.min = parseInt(value);
      }

      // hours
      if ((value=getMatch('H'))) {
        // 24h clock
        date.hour = parseInt(value);
      } else if ((value = getMatch('I'))) {
        // AM/PM clock
        var hour = parseInt(value);
        if ((value=getMatch('p'))) {
          hour += value.toUpperCase()[0] === 'P' ? 12 : 0;
        }
        date.hour = hour;
      }

      // year
      if ((value=getMatch('Y'))) {
        // parse from four-digit year
        date.year = parseInt(value);
      } else if ((value=getMatch('y'))) {
        // parse from two-digit year...
        var year = parseInt(value);
        if ((value=getMatch('C'))) {
          // ...and century
          year += parseInt(value)*100;
        } else {
          // ...and rule-of-thumb
          year += year<69 ? 2000 : 1900;
        }
        date.year = year;
      }

      // month
      if ((value=getMatch('m'))) {
        // parse from month number
        date.month = parseInt(value)-1;
      } else if ((value=getMatch('b'))) {
        // parse from month name
        date.month = MONTH_NUMBERS[value.substring(0,3).toUpperCase()] || 0;
        // TODO: derive month from day in year+year, week number+day of week+year 
      }

      // day
      if ((value=getMatch('d'))) {
        // get day of month directly
        date.day = parseInt(value);
      } else if ((value=getMatch('j'))) {
        // get day of month from day of year ...
        var day = parseInt(value);
        var leapYear = __isLeapYear(date.year);
        for (var month=0; month<12; ++month) {
          var daysUntilMonth = __arraySum(leapYear ? __MONTH_DAYS_LEAP : __MONTH_DAYS_REGULAR, month-1);
          if (day<=daysUntilMonth+(leapYear ? __MONTH_DAYS_LEAP : __MONTH_DAYS_REGULAR)[month]) {
            date.day = day-daysUntilMonth;
          }
        }
      } else if ((value=getMatch('a'))) {
        // get day of month from weekday ...
        var weekDay = value.substring(0,3).toUpperCase();
        if ((value=getMatch('U'))) {
          // ... and week number (Sunday being first day of week)
          // Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. 
          // All days in a new year preceding the first Sunday are considered to be in week 0.
          var weekDayNumber = DAY_NUMBERS_SUN_FIRST[weekDay];
          var weekNumber = parseInt(value);

          // January 1st 
          var janFirst = new Date(date.year, 0, 1);
          var endDate;
          if (janFirst.getDay() === 0) {
            // Jan 1st is a Sunday, and, hence in the 1st CW
            endDate = __addDays(janFirst, weekDayNumber+7*(weekNumber-1));
          } else {
            // Jan 1st is not a Sunday, and, hence still in the 0th CW
            endDate = __addDays(janFirst, 7-janFirst.getDay()+weekDayNumber+7*(weekNumber-1));
          }
          date.day = endDate.getDate();
          date.month = endDate.getMonth();
        } else if ((value=getMatch('W'))) {
          // ... and week number (Monday being first day of week)
          // Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. 
          // All days in a new year preceding the first Monday are considered to be in week 0.
          var weekDayNumber = DAY_NUMBERS_MON_FIRST[weekDay];
          var weekNumber = parseInt(value);

          // January 1st 
          var janFirst = new Date(date.year, 0, 1);
          var endDate;
          if (janFirst.getDay()===1) {
            // Jan 1st is a Monday, and, hence in the 1st CW
             endDate = __addDays(janFirst, weekDayNumber+7*(weekNumber-1));
          } else {
            // Jan 1st is not a Monday, and, hence still in the 0th CW
            endDate = __addDays(janFirst, 7-janFirst.getDay()+1+weekDayNumber+7*(weekNumber-1));
          }

          date.day = endDate.getDate();
          date.month = endDate.getMonth();
        }
      }

      /*
      tm_sec  int seconds after the minute  0-61*
      tm_min  int minutes after the hour  0-59
      tm_hour int hours since midnight  0-23
      tm_mday int day of the month  1-31
      tm_mon  int months since January  0-11
      tm_year int years since 1900  
      tm_wday int days since Sunday 0-6
      tm_yday int days since January 1  0-365
      tm_isdst  int Daylight Saving Time flag 
      */

      var fullDate = new Date(date.year, date.month, date.day, date.hour, date.min, date.sec, 0);
      {{{ makeSetValue('tm', C_STRUCTS.tm.tm_sec, 'fullDate.getSeconds()', 'i32') }}};
      {{{ makeSetValue('tm', C_STRUCTS.tm.tm_min, 'fullDate.getMinutes()', 'i32') }}};
      {{{ makeSetValue('tm', C_STRUCTS.tm.tm_hour, 'fullDate.getHours()', 'i32') }}};
      {{{ makeSetValue('tm', C_STRUCTS.tm.tm_mday, 'fullDate.getDate()', 'i32') }}};
      {{{ makeSetValue('tm', C_STRUCTS.tm.tm_mon, 'fullDate.getMonth()', 'i32') }}};
      {{{ makeSetValue('tm', C_STRUCTS.tm.tm_year, 'fullDate.getFullYear()-1900', 'i32') }}};
      {{{ makeSetValue('tm', C_STRUCTS.tm.tm_wday, 'fullDate.getDay()', 'i32') }}};
      {{{ makeSetValue('tm', C_STRUCTS.tm.tm_yday, '__arraySum(__isLeapYear(fullDate.getFullYear()) ? __MONTH_DAYS_LEAP : __MONTH_DAYS_REGULAR, fullDate.getMonth()-1)+fullDate.getDate()-1', 'i32') }}};
      {{{ makeSetValue('tm', C_STRUCTS.tm.tm_isdst, '0', 'i32') }}};

      // we need to convert the matched sequence into an integer array to take care of UTF-8 characters > 0x7F
      // TODO: not sure that intArrayFromString handles all unicode characters correctly
      return buf+intArrayFromString(matches[0]).length-1;
    } 

    return 0;
  },
  strptime_l__deps: ['strptime'],
  strptime_l: function(buf, format, tm) {
    return _strptime(buf, format, tm); // no locale support yet
  },

  getdate: function(string) {
    // struct tm *getdate(const char *string);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/getdate.html
    // TODO: Implement.
    return 0;
  },

  // ==========================================================================
  // sys/time.h
  // ==========================================================================

  nanosleep__deps: ['usleep'],
  nanosleep: function(rqtp, rmtp) {
    // int nanosleep(const struct timespec  *rqtp, struct timespec *rmtp);
    var seconds = {{{ makeGetValue('rqtp', C_STRUCTS.timespec.tv_sec, 'i32') }}};
    var nanoseconds = {{{ makeGetValue('rqtp', C_STRUCTS.timespec.tv_nsec, 'i32') }}};
    if (rmtp !== 0) {
      {{{ makeSetValue('rmtp', C_STRUCTS.timespec.tv_sec, '0', 'i32') }}};
      {{{ makeSetValue('rmtp', C_STRUCTS.timespec.tv_nsec, '0', 'i32') }}};
    }
    return _usleep((seconds * 1e6) + (nanoseconds / 1000));
  },
  clock_gettime__deps: ['emscripten_get_now', 'emscripten_get_now_is_monotonic', '$ERRNO_CODES', '__setErrNo'],
  clock_gettime: function(clk_id, tp) {
    // int clock_gettime(clockid_t clk_id, struct timespec *tp);
    var now;
    if (clk_id === {{{ cDefine('CLOCK_REALTIME') }}}) {
      now = Date.now();
    } else if (clk_id === {{{ cDefine('CLOCK_MONOTONIC') }}} && _emscripten_get_now_is_monotonic()) {
      now = _emscripten_get_now();
    } else {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    }
    {{{ makeSetValue('tp', C_STRUCTS.timespec.tv_sec, '(now/1000)|0', 'i32') }}}; // seconds
    {{{ makeSetValue('tp', C_STRUCTS.timespec.tv_nsec, '((now % 1000)*1000*1000)|0', 'i32') }}}; // nanoseconds
    return 0;
  },
  clock_settime__deps: ['$ERRNO_CODES', '__setErrNo'],
  clock_settime: function(clk_id, tp) {
    // int clock_settime(clockid_t clk_id, const struct timespec *tp);
    // Nothing.
    ___setErrNo(clk_id === {{{ cDefine('CLOCK_REALTIME') }}} ? ERRNO_CODES.EPERM
                                                             : ERRNO_CODES.EINVAL);
    return -1;
  },
  clock_getres__deps: ['emscripten_get_now_res', 'emscripten_get_now_is_monotonic', '$ERRNO_CODES', '__setErrNo'],
  clock_getres: function(clk_id, res) {
    // int clock_getres(clockid_t clk_id, struct timespec *res);
    var nsec;
    if (clk_id === {{{ cDefine('CLOCK_REALTIME') }}}) {
      nsec = 1000 * 1000; // educated guess that it's milliseconds
    } else if (clk_id === {{{ cDefine('CLOCK_MONOTONIC') }}} && _emscripten_get_now_is_monotonic()) {
      nsec = _emscripten_get_now_res();
    } else {
      ___setErrNo(ERRNO_CODES.EINVAL);
      return -1;
    }
    {{{ makeSetValue('res', C_STRUCTS.timespec.tv_sec, '(nsec/1000000000)|0', 'i32') }}};
    {{{ makeSetValue('res', C_STRUCTS.timespec.tv_nsec, 'nsec', 'i32') }}} // resolution is nanoseconds
    return 0;
  },

  // http://pubs.opengroup.org/onlinepubs/000095399/basedefs/sys/time.h.html
  gettimeofday: function(ptr) {
    var now = Date.now();
    {{{ makeSetValue('ptr', C_STRUCTS.timeval.tv_sec, '(now/1000)|0', 'i32') }}}; // seconds
    {{{ makeSetValue('ptr', C_STRUCTS.timeval.tv_usec, '((now % 1000)*1000)|0', 'i32') }}}; // microseconds
    return 0;
  },

  // ==========================================================================
  // sys/timeb.h
  // ==========================================================================
  
  ftime: function(p) {
    var millis = Date.now();
    {{{ makeSetValue('p', C_STRUCTS.timeb.time, '(millis/1000)|0', 'i32') }}};
    {{{ makeSetValue('p', C_STRUCTS.timeb.millitm, 'millis % 1000', 'i16') }}};
    {{{ makeSetValue('p', C_STRUCTS.timeb.timezone, '0', 'i16') }}}; // Obsolete field
    {{{ makeSetValue('p', C_STRUCTS.timeb.dstflag, '0', 'i16') }}}; // Obsolete field
    return 0;
  },

  // ==========================================================================
  // sys/times.h
  // ==========================================================================

  times__deps: ['memset'],
  times: function(buffer) {
    // clock_t times(struct tms *buffer);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/times.html
    // NOTE: This is fake, since we can't calculate real CPU time usage in JS.
    if (buffer !== 0) {
      _memset(buffer, 0, {{{ C_STRUCTS.tms.__size__ }}});
    }
    return 0;
  },

  // ==========================================================================
  // sys/types.h
  // ==========================================================================
  // http://www.kernel.org/doc/man-pages/online/pages/man3/minor.3.html
  makedev: function(maj, min) {
    return ((maj) << 8 | (min));
  },
  gnu_dev_makedev: 'makedev',
  major: function(dev) {
    return ((dev) >> 8);
  },
  gnu_dev_major: 'major',
  minor: function(dev) {
    return ((dev) & 0xff);
  },
  gnu_dev_minor: 'minor',

  // ==========================================================================
  // setjmp.h
  // ==========================================================================

  saveSetjmp__asm: true,
  saveSetjmp__sig: 'iii',
  saveSetjmp__deps: ['realloc'],
  saveSetjmp: function(env, label, table, size) {
    // Not particularly fast: slow table lookup of setjmpId to label. But setjmp
    // prevents relooping anyhow, so slowness is to be expected. And typical case
    // is 1 setjmp per invocation, or less.
    env = env|0;
    label = label|0;
    table = table|0;
    size = size|0;
    var i = 0;
    setjmpId = (setjmpId+1)|0;
    {{{ makeSetValueAsm('env', '0', 'setjmpId', 'i32') }}};
    while ((i|0) < (size|0)) {
      if ({{{ makeGetValueAsm('table', '(i<<3)', 'i32') }}} == 0) {
        {{{ makeSetValueAsm('table', '(i<<3)', 'setjmpId', 'i32') }}};
        {{{ makeSetValueAsm('table', '(i<<3)+4', 'label', 'i32') }}};
        // prepare next slot
        {{{ makeSetValueAsm('table', '(i<<3)+8', '0', 'i32') }}};
        {{{ makeSetTempRet0('size') }}};
        return table | 0;
      }
      i = i+1|0;
    }
    // grow the table
    size = (size*2)|0;
    table = _realloc(table|0, 8*(size+1|0)|0) | 0;
    table = _saveSetjmp(env|0, label|0, table|0, size|0) | 0;
    {{{ makeSetTempRet0('size') }}};
    return table | 0;
  },

  testSetjmp__asm: true,
  testSetjmp__sig: 'iii',
  testSetjmp: function(id, table, size) {
    id = id|0;
    table = table|0;
    size = size|0;
    var i = 0, curr = 0;
    while ((i|0) < (size|0)) {
      curr = {{{ makeGetValueAsm('table', '(i<<3)', 'i32') }}};
      if ((curr|0) == 0) break;
      if ((curr|0) == (id|0)) {
        return {{{ makeGetValueAsm('table', '(i<<3)+4', 'i32') }}};
      }
      i = i+1|0;
    }
    return 0;
  },

  setjmp__deps: ['saveSetjmp', 'testSetjmp'],
  setjmp__inline: function(env) {
    // Save the label
    return '_saveSetjmp(' + env + ', label, setjmpTable)|0';
  },

  longjmp__deps: ['saveSetjmp', 'testSetjmp'],
  longjmp: function(env, value) {
    asm['setThrew'](env, value || 1);
    throw 'longjmp';
  },
  emscripten_longjmp__deps: ['longjmp'],
  emscripten_longjmp: function(env, value) {
    _longjmp(env, value);
  },

  // ==========================================================================
  // sys/wait.h
  // ==========================================================================

  wait__deps: ['$ERRNO_CODES', '__setErrNo'],
  wait: function(stat_loc) {
    // pid_t wait(int *stat_loc);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/wait.html
    // Makes no sense in a single-process environment.
    ___setErrNo(ERRNO_CODES.ECHILD);
    return -1;
  },
  // NOTE: These aren't really the same, but we use the same stub for them all.
  waitid: 'wait',
  waitpid: 'wait',
  wait3: 'wait',
  wait4: 'wait',

  // ==========================================================================
  // locale.h
  // ==========================================================================

  $LOCALE: {
    curr: 0,
    check: function(locale) {
      if (locale) locale = Pointer_stringify(locale);
      return locale === 'C' || locale === 'POSIX' || !locale;
    },
  },

  newlocale__deps: ['$LOCALE', 'calloc'],
  newlocale: function(mask, locale, base) {
    if (!LOCALE.check(locale)) {
      ___setErrNo(ERRNO_CODES.ENOENT);
      return 0;
    }
    if (!base) base = _calloc(1, 4);
    return base;
  },

  freelocale__deps: ['$LOCALE', 'free'],
  freelocale: function(locale) {
    _free(locale);
  },

  uselocale__deps: ['$LOCALE'],
  uselocale: function(locale) {
    var old = LOCALE.curr;
    if (locale) LOCALE.curr = locale;
    return old;
  },

  setlocale__deps: ['$LOCALE'],
  setlocale: function(category, locale) {
    if (LOCALE.check(locale)) {
      if (!_setlocale.ret) _setlocale.ret = allocate(intArrayFromString('C'), 'i8', ALLOC_NORMAL);
      return _setlocale.ret;
    }
    return 0;
  },

  localeconv: function() {
    // %struct.timeval = type { char* decimal point, other stuff... }
    // var indexes = Runtime.calculateStructAlignment({ fields: ['i32', 'i32'] });
    var me = _localeconv;
    if (!me.ret) {
    // These are defaults from the "C" locale
      me.ret = allocate([
        allocate(intArrayFromString('.'), 'i8', ALLOC_NORMAL),0,0,0, // decimal_point
        allocate(intArrayFromString(''), 'i8', ALLOC_NORMAL),0,0,0, // thousands_sep
        allocate(intArrayFromString(''), 'i8', ALLOC_NORMAL),0,0,0, // grouping
        allocate(intArrayFromString(''), 'i8', ALLOC_NORMAL),0,0,0, // int_curr_symbol
        allocate(intArrayFromString(''), 'i8', ALLOC_NORMAL),0,0,0, // currency_symbol
        allocate(intArrayFromString(''), 'i8', ALLOC_NORMAL),0,0,0, // mon_decimal_point
        allocate(intArrayFromString(''), 'i8', ALLOC_NORMAL),0,0,0, // mon_thousands_sep
        allocate(intArrayFromString(''), 'i8', ALLOC_NORMAL),0,0,0, // mon_grouping
        allocate(intArrayFromString(''), 'i8', ALLOC_NORMAL),0,0,0, // positive_sign
        allocate(intArrayFromString(''), 'i8', ALLOC_NORMAL),0,0,0 // negative_sign
      ], 'i8*', ALLOC_NORMAL); // Allocate strings in lconv, still don't allocate chars
    }
    return me.ret;
  },

  __locale_mb_cur_max: function() { throw '__locale_mb_cur_max not implemented' },

  // ==========================================================================
  // langinfo.h
  // ==========================================================================

  nl_langinfo: function(item) {
    // char *nl_langinfo(nl_item item);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/nl_langinfo.html
    var result;
    switch (item) {
      case {{{ cDefine('CODESET') }}}:
        result = 'ANSI_X3.4-1968';
        break;
      case {{{ cDefine('D_T_FMT') }}}:
        result = '%a %b %e %H:%M:%S %Y';
        break;
      case {{{ cDefine('D_FMT') }}}:
        result = '%m/%d/%y';
        break;
      case {{{ cDefine('T_FMT') }}}:
        result = '%H:%M:%S';
        break;
      case {{{ cDefine('T_FMT_AMPM') }}}:
        result = '%I:%M:%S %p';
        break;
      case {{{ cDefine('AM_STR') }}}:
        result = 'AM';
        break;
      case {{{ cDefine('PM_STR') }}}:
        result = 'PM';
        break;
      case {{{ cDefine('DAY_1') }}}:
        result = 'Sunday';
        break;
      case {{{ cDefine('DAY_2') }}}:
        result = 'Monday';
        break;
      case {{{ cDefine('DAY_3') }}}:
        result = 'Tuesday';
        break;
      case {{{ cDefine('DAY_4') }}}:
        result = 'Wednesday';
        break;
      case {{{ cDefine('DAY_5') }}}:
        result = 'Thursday';
        break;
      case {{{ cDefine('DAY_6') }}}:
        result = 'Friday';
        break;
      case {{{ cDefine('DAY_7') }}}:
        result = 'Saturday';
        break;
      case {{{ cDefine('ABDAY_1') }}}:
        result = 'Sun';
        break;
      case {{{ cDefine('ABDAY_2') }}}:
        result = 'Mon';
        break;
      case {{{ cDefine('ABDAY_3') }}}:
        result = 'Tue';
        break;
      case {{{ cDefine('ABDAY_4') }}}:
        result = 'Wed';
        break;
      case {{{ cDefine('ABDAY_5') }}}:
        result = 'Thu';
        break;
      case {{{ cDefine('ABDAY_6') }}}:
        result = 'Fri';
        break;
      case {{{ cDefine('ABDAY_7') }}}:
        result = 'Sat';
        break;
      case {{{ cDefine('MON_1') }}}:
        result = 'January';
        break;
      case {{{ cDefine('MON_2') }}}:
        result = 'February';
        break;
      case {{{ cDefine('MON_3') }}}:
        result = 'March';
        break;
      case {{{ cDefine('MON_4') }}}:
        result = 'April';
        break;
      case {{{ cDefine('MON_5') }}}:
        result = 'May';
        break;
      case {{{ cDefine('MON_6') }}}:
        result = 'June';
        break;
      case {{{ cDefine('MON_7') }}}:
        result = 'July';
        break;
      case {{{ cDefine('MON_8') }}}:
        result = 'August';
        break;
      case {{{ cDefine('MON_9') }}}:
        result = 'September';
        break;
      case {{{ cDefine('MON_10') }}}:
        result = 'October';
        break;
      case {{{ cDefine('MON_11') }}}:
        result = 'November';
        break;
      case {{{ cDefine('MON_12') }}}:
        result = 'December';
        break;
      case {{{ cDefine('ABMON_1') }}}:
        result = 'Jan';
        break;
      case {{{ cDefine('ABMON_2') }}}:
        result = 'Feb';
        break;
      case {{{ cDefine('ABMON_3') }}}:
        result = 'Mar';
        break;
      case {{{ cDefine('ABMON_4') }}}:
        result = 'Apr';
        break;
      case {{{ cDefine('ABMON_5') }}}:
        result = 'May';
        break;
      case {{{ cDefine('ABMON_6') }}}:
        result = 'Jun';
        break;
      case {{{ cDefine('ABMON_7') }}}:
        result = 'Jul';
        break;
      case {{{ cDefine('ABMON_8') }}}:
        result = 'Aug';
        break;
      case {{{ cDefine('ABMON_9') }}}:
        result = 'Sep';
        break;
      case {{{ cDefine('ABMON_10') }}}:
        result = 'Oct';
        break;
      case {{{ cDefine('ABMON_11') }}}:
        result = 'Nov';
        break;
      case {{{ cDefine('ABMON_12') }}}:
        result = 'Dec';
        break;
      case {{{ cDefine('ALT_DIGITS') }}}:
        result = '';
        break;
      case {{{ cDefine('RADIXCHAR') }}}:
        result = '.';
        break;
      case {{{ cDefine('THOUSEP') }}}:
        result = '';
        break;
      case {{{ cDefine('YESEXPR') }}}:
        result = '^[yY]';
        break;
      case {{{ cDefine('NOEXPR') }}}:
        result = '^[nN]';
        break;
      case {{{ cDefine('CRNCYSTR') }}}:
        result = '-';
        break;
      case {{{ cDefine('ERA') }}}:
      case {{{ cDefine('ERA_D_FMT') }}}:
      case {{{ cDefine('ERA_D_T_FMT') }}}:
      case {{{ cDefine('ERA_T_FMT') }}}:
      default:
        result = '';
        break;
    }

    var me = _nl_langinfo;
    if (!me.ret) me.ret = _malloc(32);
    writeAsciiToMemory(result, me.ret);
    return me.ret;
  },

  // ==========================================================================
  // errno.h
  // ==========================================================================

  $ERRNO_CODES: {
    EPERM: {{{ cDefine('EPERM') }}},
    ENOENT: {{{ cDefine('ENOENT') }}},
    ESRCH: {{{ cDefine('ESRCH') }}},
    EINTR: {{{ cDefine('EINTR') }}},
    EIO: {{{ cDefine('EIO') }}},
    ENXIO: {{{ cDefine('ENXIO') }}},
    E2BIG: {{{ cDefine('E2BIG') }}},
    ENOEXEC: {{{ cDefine('ENOEXEC') }}},
    EBADF: {{{ cDefine('EBADF') }}},
    ECHILD: {{{ cDefine('ECHILD') }}},
    EAGAIN: {{{ cDefine('EAGAIN') }}},
    EWOULDBLOCK: {{{ cDefine('EWOULDBLOCK') }}},
    ENOMEM: {{{ cDefine('ENOMEM') }}},
    EACCES: {{{ cDefine('EACCES') }}},
    EFAULT: {{{ cDefine('EFAULT') }}},
    ENOTBLK: {{{ cDefine('ENOTBLK') }}},
    EBUSY: {{{ cDefine('EBUSY') }}},
    EEXIST: {{{ cDefine('EEXIST') }}},
    EXDEV: {{{ cDefine('EXDEV') }}},
    ENODEV: {{{ cDefine('ENODEV') }}},
    ENOTDIR: {{{ cDefine('ENOTDIR') }}},
    EISDIR: {{{ cDefine('EISDIR') }}},
    EINVAL: {{{ cDefine('EINVAL') }}},
    ENFILE: {{{ cDefine('ENFILE') }}},
    EMFILE: {{{ cDefine('EMFILE') }}},
    ENOTTY: {{{ cDefine('ENOTTY') }}},
    ETXTBSY: {{{ cDefine('ETXTBSY') }}},
    EFBIG: {{{ cDefine('EFBIG') }}},
    ENOSPC: {{{ cDefine('ENOSPC') }}},
    ESPIPE: {{{ cDefine('ESPIPE') }}},
    EROFS: {{{ cDefine('EROFS') }}},
    EMLINK: {{{ cDefine('EMLINK') }}},
    EPIPE: {{{ cDefine('EPIPE') }}},
    EDOM: {{{ cDefine('EDOM') }}},
    ERANGE: {{{ cDefine('ERANGE') }}},
    ENOMSG: {{{ cDefine('ENOMSG') }}},
    EIDRM: {{{ cDefine('EIDRM') }}},
    ECHRNG: {{{ cDefine('ECHRNG') }}},
    EL2NSYNC: {{{ cDefine('EL2NSYNC') }}},
    EL3HLT: {{{ cDefine('EL3HLT') }}},
    EL3RST: {{{ cDefine('EL3RST') }}},
    ELNRNG: {{{ cDefine('ELNRNG') }}},
    EUNATCH: {{{ cDefine('EUNATCH') }}},
    ENOCSI: {{{ cDefine('ENOCSI') }}},
    EL2HLT: {{{ cDefine('EL2HLT') }}},
    EDEADLK: {{{ cDefine('EDEADLK') }}},
    ENOLCK: {{{ cDefine('ENOLCK') }}},
    EBADE: {{{ cDefine('EBADE') }}},
    EBADR: {{{ cDefine('EBADR') }}},
    EXFULL: {{{ cDefine('EXFULL') }}},
    ENOANO: {{{ cDefine('ENOANO') }}},
    EBADRQC: {{{ cDefine('EBADRQC') }}},
    EBADSLT: {{{ cDefine('EBADSLT') }}},
    EDEADLOCK: {{{ cDefine('EDEADLOCK') }}},
    EBFONT: {{{ cDefine('EBFONT') }}},
    ENOSTR: {{{ cDefine('ENOSTR') }}},
    ENODATA: {{{ cDefine('ENODATA') }}},
    ETIME: {{{ cDefine('ETIME') }}},
    ENOSR: {{{ cDefine('ENOSR') }}},
    ENONET: {{{ cDefine('ENONET') }}},
    ENOPKG: {{{ cDefine('ENOPKG') }}},
    EREMOTE: {{{ cDefine('EREMOTE') }}},
    ENOLINK: {{{ cDefine('ENOLINK') }}},
    EADV: {{{ cDefine('EADV') }}},
    ESRMNT: {{{ cDefine('ESRMNT') }}},
    ECOMM: {{{ cDefine('ECOMM') }}},
    EPROTO: {{{ cDefine('EPROTO') }}},
    EMULTIHOP: {{{ cDefine('EMULTIHOP') }}},
    EDOTDOT: {{{ cDefine('EDOTDOT') }}},
    EBADMSG: {{{ cDefine('EBADMSG') }}},
    ENOTUNIQ: {{{ cDefine('ENOTUNIQ') }}},
    EBADFD: {{{ cDefine('EBADFD') }}},
    EREMCHG: {{{ cDefine('EREMCHG') }}},
    ELIBACC: {{{ cDefine('ELIBACC') }}},
    ELIBBAD: {{{ cDefine('ELIBBAD') }}},
    ELIBSCN: {{{ cDefine('ELIBSCN') }}},
    ELIBMAX: {{{ cDefine('ELIBMAX') }}},
    ELIBEXEC: {{{ cDefine('ELIBEXEC') }}},
    ENOSYS: {{{ cDefine('ENOSYS') }}},
    ENOTEMPTY: {{{ cDefine('ENOTEMPTY') }}},
    ENAMETOOLONG: {{{ cDefine('ENAMETOOLONG') }}},
    ELOOP: {{{ cDefine('ELOOP') }}},
    EOPNOTSUPP: {{{ cDefine('EOPNOTSUPP') }}},
    EPFNOSUPPORT: {{{ cDefine('EPFNOSUPPORT') }}},
    ECONNRESET: {{{ cDefine('ECONNRESET') }}},
    ENOBUFS: {{{ cDefine('ENOBUFS') }}},
    EAFNOSUPPORT: {{{ cDefine('EAFNOSUPPORT') }}},
    EPROTOTYPE: {{{ cDefine('EPROTOTYPE') }}},
    ENOTSOCK: {{{ cDefine('ENOTSOCK') }}},
    ENOPROTOOPT: {{{ cDefine('ENOPROTOOPT') }}},
    ESHUTDOWN: {{{ cDefine('ESHUTDOWN') }}},
    ECONNREFUSED: {{{ cDefine('ECONNREFUSED') }}},
    EADDRINUSE: {{{ cDefine('EADDRINUSE') }}},
    ECONNABORTED: {{{ cDefine('ECONNABORTED') }}},
    ENETUNREACH: {{{ cDefine('ENETUNREACH') }}},
    ENETDOWN: {{{ cDefine('ENETDOWN') }}},
    ETIMEDOUT: {{{ cDefine('ETIMEDOUT') }}},
    EHOSTDOWN: {{{ cDefine('EHOSTDOWN') }}},
    EHOSTUNREACH: {{{ cDefine('EHOSTUNREACH') }}},
    EINPROGRESS: {{{ cDefine('EINPROGRESS') }}},
    EALREADY: {{{ cDefine('EALREADY') }}},
    EDESTADDRREQ: {{{ cDefine('EDESTADDRREQ') }}},
    EMSGSIZE: {{{ cDefine('EMSGSIZE') }}},
    EPROTONOSUPPORT: {{{ cDefine('EPROTONOSUPPORT') }}},
    ESOCKTNOSUPPORT: {{{ cDefine('ESOCKTNOSUPPORT') }}},
    EADDRNOTAVAIL: {{{ cDefine('EADDRNOTAVAIL') }}},
    ENETRESET: {{{ cDefine('ENETRESET') }}},
    EISCONN: {{{ cDefine('EISCONN') }}},
    ENOTCONN: {{{ cDefine('ENOTCONN') }}},
    ETOOMANYREFS: {{{ cDefine('ETOOMANYREFS') }}},
    EUSERS: {{{ cDefine('EUSERS') }}},
    EDQUOT: {{{ cDefine('EDQUOT') }}},
    ESTALE: {{{ cDefine('ESTALE') }}},
    ENOTSUP: {{{ cDefine('ENOTSUP') }}},
    ENOMEDIUM: {{{ cDefine('ENOMEDIUM') }}},
    EILSEQ: {{{ cDefine('EILSEQ') }}},
    EOVERFLOW: {{{ cDefine('EOVERFLOW') }}},
    ECANCELED: {{{ cDefine('ECANCELED') }}},
    ENOTRECOVERABLE: {{{ cDefine('ENOTRECOVERABLE') }}},
    EOWNERDEAD: {{{ cDefine('EOWNERDEAD') }}},
    ESTRPIPE: {{{ cDefine('ESTRPIPE') }}},
  },
  $ERRNO_MESSAGES: {
    0: 'Success',
    {{{ cDefine('EPERM') }}}: 'Not super-user',
    {{{ cDefine('ENOENT') }}}: 'No such file or directory',
    {{{ cDefine('ESRCH') }}}: 'No such process',
    {{{ cDefine('EINTR') }}}: 'Interrupted system call',
    {{{ cDefine('EIO') }}}: 'I/O error',
    {{{ cDefine('ENXIO') }}}: 'No such device or address',
    {{{ cDefine('E2BIG') }}}: 'Arg list too long',
    {{{ cDefine('ENOEXEC') }}}: 'Exec format error',
    {{{ cDefine('EBADF') }}}: 'Bad file number',
    {{{ cDefine('ECHILD') }}}: 'No children',
    {{{ cDefine('EWOULDBLOCK') }}}: 'No more processes',
    {{{ cDefine('ENOMEM') }}}: 'Not enough core',
    {{{ cDefine('EACCES') }}}: 'Permission denied',
    {{{ cDefine('EFAULT') }}}: 'Bad address',
    {{{ cDefine('ENOTBLK') }}}: 'Block device required',
    {{{ cDefine('EBUSY') }}}: 'Mount device busy',
    {{{ cDefine('EEXIST') }}}: 'File exists',
    {{{ cDefine('EXDEV') }}}: 'Cross-device link',
    {{{ cDefine('ENODEV') }}}: 'No such device',
    {{{ cDefine('ENOTDIR') }}}: 'Not a directory',
    {{{ cDefine('EISDIR') }}}: 'Is a directory',
    {{{ cDefine('EINVAL') }}}: 'Invalid argument',
    {{{ cDefine('ENFILE') }}}: 'Too many open files in system',
    {{{ cDefine('EMFILE') }}}: 'Too many open files',
    {{{ cDefine('ENOTTY') }}}: 'Not a typewriter',
    {{{ cDefine('ETXTBSY') }}}: 'Text file busy',
    {{{ cDefine('EFBIG') }}}: 'File too large',
    {{{ cDefine('ENOSPC') }}}: 'No space left on device',
    {{{ cDefine('ESPIPE') }}}: 'Illegal seek',
    {{{ cDefine('EROFS') }}}: 'Read only file system',
    {{{ cDefine('EMLINK') }}}: 'Too many links',
    {{{ cDefine('EPIPE') }}}: 'Broken pipe',
    {{{ cDefine('EDOM') }}}: 'Math arg out of domain of func',
    {{{ cDefine('ERANGE') }}}: 'Math result not representable',
    {{{ cDefine('ENOMSG') }}}: 'No message of desired type',
    {{{ cDefine('EIDRM') }}}: 'Identifier removed',
    {{{ cDefine('ECHRNG') }}}: 'Channel number out of range',
    {{{ cDefine('EL2NSYNC') }}}: 'Level 2 not synchronized',
    {{{ cDefine('EL3HLT') }}}: 'Level 3 halted',
    {{{ cDefine('EL3RST') }}}: 'Level 3 reset',
    {{{ cDefine('ELNRNG') }}}: 'Link number out of range',
    {{{ cDefine('EUNATCH') }}}: 'Protocol driver not attached',
    {{{ cDefine('ENOCSI') }}}: 'No CSI structure available',
    {{{ cDefine('EL2HLT') }}}: 'Level 2 halted',
    {{{ cDefine('EDEADLK') }}}: 'Deadlock condition',
    {{{ cDefine('ENOLCK') }}}: 'No record locks available',
    {{{ cDefine('EBADE') }}}: 'Invalid exchange',
    {{{ cDefine('EBADR') }}}: 'Invalid request descriptor',
    {{{ cDefine('EXFULL') }}}: 'Exchange full',
    {{{ cDefine('ENOANO') }}}: 'No anode',
    {{{ cDefine('EBADRQC') }}}: 'Invalid request code',
    {{{ cDefine('EBADSLT') }}}: 'Invalid slot',
    {{{ cDefine('EDEADLOCK') }}}: 'File locking deadlock error',
    {{{ cDefine('EBFONT') }}}: 'Bad font file fmt',
    {{{ cDefine('ENOSTR') }}}: 'Device not a stream',
    {{{ cDefine('ENODATA') }}}: 'No data (for no delay io)',
    {{{ cDefine('ETIME') }}}: 'Timer expired',
    {{{ cDefine('ENOSR') }}}: 'Out of streams resources',
    {{{ cDefine('ENONET') }}}: 'Machine is not on the network',
    {{{ cDefine('ENOPKG') }}}: 'Package not installed',
    {{{ cDefine('EREMOTE') }}}: 'The object is remote',
    {{{ cDefine('ENOLINK') }}}: 'The link has been severed',
    {{{ cDefine('EADV') }}}: 'Advertise error',
    {{{ cDefine('ESRMNT') }}}: 'Srmount error',
    {{{ cDefine('ECOMM') }}}: 'Communication error on send',
    {{{ cDefine('EPROTO') }}}: 'Protocol error',
    {{{ cDefine('EMULTIHOP') }}}: 'Multihop attempted',
    {{{ cDefine('EDOTDOT') }}}: 'Cross mount point (not really error)',
    {{{ cDefine('EBADMSG') }}}: 'Trying to read unreadable message',
    {{{ cDefine('ENOTUNIQ') }}}: 'Given log. name not unique',
    {{{ cDefine('EBADFD') }}}: 'f.d. invalid for this operation',
    {{{ cDefine('EREMCHG') }}}: 'Remote address changed',
    {{{ cDefine('ELIBACC') }}}: 'Can   access a needed shared lib',
    {{{ cDefine('ELIBBAD') }}}: 'Accessing a corrupted shared lib',
    {{{ cDefine('ELIBSCN') }}}: '.lib section in a.out corrupted',
    {{{ cDefine('ELIBMAX') }}}: 'Attempting to link in too many libs',
    {{{ cDefine('ELIBEXEC') }}}: 'Attempting to exec a shared library',
    {{{ cDefine('ENOSYS') }}}: 'Function not implemented',
    {{{ cDefine('ENOTEMPTY') }}}: 'Directory not empty',
    {{{ cDefine('ENAMETOOLONG') }}}: 'File or path name too long',
    {{{ cDefine('ELOOP') }}}: 'Too many symbolic links',
    {{{ cDefine('EOPNOTSUPP') }}}: 'Operation not supported on transport endpoint',
    {{{ cDefine('EPFNOSUPPORT') }}}: 'Protocol family not supported',
    {{{ cDefine('ECONNRESET') }}}: 'Connection reset by peer',
    {{{ cDefine('ENOBUFS') }}}: 'No buffer space available',
    {{{ cDefine('EAFNOSUPPORT') }}}: 'Address family not supported by protocol family',
    {{{ cDefine('EPROTOTYPE') }}}: 'Protocol wrong type for socket',
    {{{ cDefine('ENOTSOCK') }}}: 'Socket operation on non-socket',
    {{{ cDefine('ENOPROTOOPT') }}}: 'Protocol not available',
    {{{ cDefine('ESHUTDOWN') }}}: 'Can\'t send after socket shutdown',
    {{{ cDefine('ECONNREFUSED') }}}: 'Connection refused',
    {{{ cDefine('EADDRINUSE') }}}: 'Address already in use',
    {{{ cDefine('ECONNABORTED') }}}: 'Connection aborted',
    {{{ cDefine('ENETUNREACH') }}}: 'Network is unreachable',
    {{{ cDefine('ENETDOWN') }}}: 'Network interface is not configured',
    {{{ cDefine('ETIMEDOUT') }}}: 'Connection timed out',
    {{{ cDefine('EHOSTDOWN') }}}: 'Host is down',
    {{{ cDefine('EHOSTUNREACH') }}}: 'Host is unreachable',
    {{{ cDefine('EINPROGRESS') }}}: 'Connection already in progress',
    {{{ cDefine('EALREADY') }}}: 'Socket already connected',
    {{{ cDefine('EDESTADDRREQ') }}}: 'Destination address required',
    {{{ cDefine('EMSGSIZE') }}}: 'Message too long',
    {{{ cDefine('EPROTONOSUPPORT') }}}: 'Unknown protocol',
    {{{ cDefine('ESOCKTNOSUPPORT') }}}: 'Socket type not supported',
    {{{ cDefine('EADDRNOTAVAIL') }}}: 'Address not available',
    {{{ cDefine('ENETRESET') }}}: 'Connection reset by network',
    {{{ cDefine('EISCONN') }}}: 'Socket is already connected',
    {{{ cDefine('ENOTCONN') }}}: 'Socket is not connected',
    {{{ cDefine('ETOOMANYREFS') }}}: 'Too many references',
    {{{ cDefine('EUSERS') }}}: 'Too many users',
    {{{ cDefine('EDQUOT') }}}: 'Quota exceeded',
    {{{ cDefine('ESTALE') }}}: 'Stale file handle',
    {{{ cDefine('ENOTSUP') }}}: 'Not supported',
    {{{ cDefine('ENOMEDIUM') }}}: 'No medium (in tape drive)',
    {{{ cDefine('EILSEQ') }}}: 'Illegal byte sequence',
    {{{ cDefine('EOVERFLOW') }}}: 'Value too large for defined data type',
    {{{ cDefine('ECANCELED') }}}: 'Operation canceled',
    {{{ cDefine('ENOTRECOVERABLE') }}}: 'State not recoverable',
    {{{ cDefine('EOWNERDEAD') }}}: 'Previous owner died',
    {{{ cDefine('ESTRPIPE') }}}: 'Streams pipe error',
  },
  __setErrNo__deps: ['__errno_location'],
  __setErrNo: function(value) {
    if (___setErrNo.loc === undefined) {
      if (Module["___errno_location"]) {
        ___setErrNo.loc = Module["___errno_location"]();
      } else {
        ___setErrNo.loc = 0; // no __errno_location, so errno is inaccessible from C code; no need to set it
      }
    }
    if (___setErrNo.loc) {
      {{{ makeSetValue('___setErrNo.loc', '0', 'value', 'i32') }}};
    }
    return value;
  },

  // ==========================================================================
  // sys/resource.h
  // ==========================================================================

  // TODO: Implement for real.
  getrlimit: function(resource, rlp) {
    // int getrlimit(int resource, struct rlimit *rlp);
    {{{ makeSetValue('rlp', C_STRUCTS.rlimit.rlim_cur, '-1', 'i32') }}};  // RLIM_INFINITY
    {{{ makeSetValue('rlp', C_STRUCTS.rlimit.rlim_cur + 4, '-1', 'i32') }}};  // RLIM_INFINITY
    {{{ makeSetValue('rlp', C_STRUCTS.rlimit.rlim_max, '-1', 'i32') }}};  // RLIM_INFINITY
    {{{ makeSetValue('rlp', C_STRUCTS.rlimit.rlim_max + 4, '-1', 'i32') }}};  // RLIM_INFINITY
    return 0;
  },
  setrlimit: function(resource, rlp) {
    // int setrlimit(int resource, const struct rlimit *rlp)
    return 0;
  },

  // TODO: Implement for real. We just do time used, and no useful data
  getrusage: function(resource, rlp) {
    // int getrusage(int resource, struct rusage *rlp);
    {{{ makeSetValue('rlp', C_STRUCTS.rusage.ru_utime.tv_sec, '1', 'i32') }}};
    {{{ makeSetValue('rlp', C_STRUCTS.rusage.ru_utime.tv_usec, '2', 'i32') }}};
    {{{ makeSetValue('rlp', C_STRUCTS.rusage.ru_stime.tv_sec, '3', 'i32') }}};
    {{{ makeSetValue('rlp', C_STRUCTS.rusage.ru_stime.tv_usec, '4', 'i32') }}};
    return 0;
  },

  // ==========================================================================
  // sched.h (stubs only - no thread support yet!)
  // ==========================================================================
  sched_yield: function() {
    return 0;
  },

  // ==========================================================================
  // pthread.h (stubs for mutexes only - no thread support yet!)
  // ==========================================================================

  pthread_mutex_init: function() {},
  pthread_mutex_destroy: function() {},
  pthread_mutexattr_init: function() {},
  pthread_mutexattr_settype: function() {},
  pthread_mutexattr_destroy: function() {},
  pthread_mutex_lock: function() {},
  pthread_mutex_unlock: function() {},
  pthread_mutex_trylock: function() {
    return 0;
  },
  pthread_mutexattr_setpshared: function(attr, pshared) {
    // XXX implement if/when getpshared is required
    return 0;
  },
  pthread_cond_init: function() {},
  pthread_cond_destroy: function() {},
  pthread_cond_broadcast: function() {
    return 0;
  },
  pthread_cond_wait: function() {
    return 0;
  },
  pthread_cond_timedwait: function() {
    return 0;
  },
  pthread_self: function() {
    //FIXME: assumes only a single thread
    return 0;
  },
  pthread_attr_init: function(attr) {
    /* int pthread_attr_init(pthread_attr_t *attr); */
    //FIXME: should allocate a pthread_attr_t
    return 0;
  },
  pthread_getattr_np: function(thread, attr) {
    /* int pthread_getattr_np(pthread_t thread, pthread_attr_t *attr); */
    //FIXME: should fill in attributes of the given thread in pthread_attr_t
    return 0;
  },
  pthread_attr_destroy: function(attr) {
    /* int pthread_attr_destroy(pthread_attr_t *attr); */
    //FIXME: should destroy the pthread_attr_t struct
    return 0;
  },
  pthread_attr_getstack: function(attr, stackaddr, stacksize) {
    /* int pthread_attr_getstack(const pthread_attr_t *restrict attr,
       void **restrict stackaddr, size_t *restrict stacksize); */
    /*FIXME: assumes that there is only one thread, and that attr is the
      current thread*/
    {{{ makeSetValue('stackaddr', '0', 'STACK_BASE', 'i8*') }}};
    {{{ makeSetValue('stacksize', '0', 'TOTAL_STACK', 'i32') }}};
    return 0;
  },

  pthread_once: function(ptr, func) {
    if (!_pthread_once.seen) _pthread_once.seen = {};
    if (ptr in _pthread_once.seen) return;
    Runtime.dynCall('v', func);
    _pthread_once.seen[ptr] = 1;
  },

  $PTHREAD_SPECIFIC: {},
  $PTHREAD_SPECIFIC_NEXT_KEY: 1,
  pthread_key_create__deps: ['$PTHREAD_SPECIFIC', '$PTHREAD_SPECIFIC_NEXT_KEY', '$ERRNO_CODES'],
  pthread_key_create: function(key, destructor) {
    if (key == 0) {
      return ERRNO_CODES.EINVAL;
    }
    {{{ makeSetValue('key', '0', 'PTHREAD_SPECIFIC_NEXT_KEY', 'i32*') }}};
    // values start at 0
    PTHREAD_SPECIFIC[PTHREAD_SPECIFIC_NEXT_KEY] = 0;
    PTHREAD_SPECIFIC_NEXT_KEY++;
    return 0;
  },

  pthread_getspecific__deps: ['$PTHREAD_SPECIFIC'],
  pthread_getspecific: function(key) {
    return PTHREAD_SPECIFIC[key] || 0;
  },

  pthread_setspecific__deps: ['$PTHREAD_SPECIFIC', '$ERRNO_CODES'],
  pthread_setspecific: function(key, value) {
    if (!(key in PTHREAD_SPECIFIC)) {
      return ERRNO_CODES.EINVAL;
    }
    PTHREAD_SPECIFIC[key] = value;
    return 0;
  },

  pthread_key_delete__deps: ['$PTHREAD_SPECIFIC', '$ERRNO_CODES'],
  pthread_key_delete: function(key) {
    if (key in PTHREAD_SPECIFIC) {
      delete PTHREAD_SPECIFIC[key];
      return 0;
    }
    return ERRNO_CODES.EINVAL;
  },

  pthread_cleanup_push: function(routine, arg) {
    __ATEXIT__.push({ func: function() { Runtime.dynCall('vi', routine, [arg]) } })
    _pthread_cleanup_push.level = __ATEXIT__.length;
  },

  pthread_cleanup_pop: function() {
    assert(_pthread_cleanup_push.level == __ATEXIT__.length, 'cannot pop if something else added meanwhile!');
    __ATEXIT__.pop();
    _pthread_cleanup_push.level = __ATEXIT__.length;
  },

  pthread_rwlock_init: function() {
    return 0; // XXX
  },

  // ==========================================================================
  // malloc.h
  // ==========================================================================

  memalign: function(boundary, size) {
    // leaks, and even returns an invalid pointer. Horrible hack... but then, this is a deprecated function...
    var ret = Runtime.staticAlloc(size + boundary);
    return ret + boundary - (ret % boundary);
  },

  posix_memalign__deps: ['memalign'],
  posix_memalign: function(memptr, alignment, size) {
    var ptr = _memalign(alignment, size);
    {{{ makeSetValue('memptr', '0', 'ptr', 'i8*') }}};
    return 0;
  },

  // ==========================================================================
  // arpa/inet.h
  // ==========================================================================
  htonl: function(value) {
    return ((value & 0xff) << 24) + ((value & 0xff00) << 8) +
           ((value & 0xff0000) >>> 8) + ((value & 0xff000000) >>> 24);
  },
  htons: function(value) {
    return ((value & 0xff) << 8) + ((value & 0xff00) >> 8);
  },
  ntohl: 'htonl',
  ntohs: 'htons',

  // old ipv4 only functions
  inet_addr__deps: ['_inet_pton4_raw'],
  inet_addr: function(ptr) {
    var addr = __inet_pton4_raw(Pointer_stringify(ptr));
    if (addr === null) {
      return -1;
    }
    return addr;
  },
  inet_ntoa__deps: ['_inet_ntop4_raw'],
  inet_ntoa: function(in_addr) {
    if (!_inet_ntoa.buffer) {
      _inet_ntoa.buffer = _malloc(1024);
    }
    var addr = {{{ makeGetValue('in_addr', '0', 'i32') }}};
    var str = __inet_ntop4_raw(addr);
    writeStringToMemory(str.substr(0, 1024), _inet_ntoa.buffer);
    return _inet_ntoa.buffer;
  },
  inet_aton__deps: ['_inet_pton4_raw'],
  inet_aton: function(cp, inp) {
    var addr = __inet_pton4_raw(Pointer_stringify(cp));
    if (addr === null) {
      return 0;
    }
    {{{ makeSetValue('inp', '0', 'addr', 'i32') }}};
    return 1;
  },

  // new ipv4 / ipv6 functions
  _inet_ntop4_raw: function(addr) {
    return (addr & 0xff) + '.' + ((addr >> 8) & 0xff) + '.' + ((addr >> 16) & 0xff) + '.' + ((addr >> 24) & 0xff)
  },
  _inet_ntop4__deps: ['__setErrNo', '$ERRNO_CODES', '_inet_ntop4_raw'],
  _inet_ntop4: function(src, dst, size) {
    var addr = {{{ makeGetValue('src', '0', 'i32') }}};
    var str = __inet_ntop4_raw(addr);
    if (str.length+1 > size) {
      ___setErrNo(ERRNO_CODES.ENOSPC);
      return 0;
    }
    writeStringToMemory(str, dst);
    return dst;
  },
  _inet_ntop6_raw__deps: ['ntohs', '_inet_ntop4_raw'],
  _inet_ntop6_raw: function(ints) {
    //  ref:  http://www.ietf.org/rfc/rfc2373.txt - section 2.5.4
    //  Format for IPv4 compatible and mapped  128-bit IPv6 Addresses
    //  128-bits are split into eight 16-bit words
    //  stored in network byte order (big-endian)
    //  |                80 bits               | 16 |      32 bits        |
    //  +-----------------------------------------------------------------+
    //  |               10 bytes               |  2 |      4 bytes        |
    //  +--------------------------------------+--------------------------+
    //  +               5 words                |  1 |      2 words        |
    //  +--------------------------------------+--------------------------+
    //  |0000..............................0000|0000|    IPv4 ADDRESS     | (compatible)
    //  +--------------------------------------+----+---------------------+
    //  |0000..............................0000|FFFF|    IPv4 ADDRESS     | (mapped)
    //  +--------------------------------------+----+---------------------+
    var str = "";
    var word = 0;
    var longest = 0;
    var lastzero = 0;
    var zstart = 0;
    var len = 0;
    var i = 0;
    var parts = [
      ints[0] & 0xffff,
      (ints[0] >> 16),
      ints[1] & 0xffff,
      (ints[1] >> 16),
      ints[2] & 0xffff,
      (ints[2] >> 16),
      ints[3] & 0xffff,
      (ints[3] >> 16)
    ];

    // Handle IPv4-compatible, IPv4-mapped, loopback and any/unspecified addresses

    var hasipv4 = true;
    var v4part = "";
    // check if the 10 high-order bytes are all zeros (first 5 words)
    for (i = 0; i < 5; i++) {
      if (parts[i] !== 0) { hasipv4 = false; break; }
    }

    if (hasipv4) {
      // low-order 32-bits store an IPv4 address (bytes 13 to 16) (last 2 words)
      v4part = __inet_ntop4_raw(parts[6] | (parts[7] << 16));
      // IPv4-mapped IPv6 address if 16-bit value (bytes 11 and 12) == 0xFFFF (6th word)
      if (parts[5] === -1) {
        str = "::ffff:";
        str += v4part;
        return str;
      }
      // IPv4-compatible IPv6 address if 16-bit value (bytes 11 and 12) == 0x0000 (6th word)
      if (parts[5] === 0) {
        str = "::";
        //special case IPv6 addresses
        if(v4part === "0.0.0.0") v4part = ""; // any/unspecified address
        if(v4part === "0.0.0.1") v4part = "1";// loopback address
        str += v4part;
        return str;
      }
    }

    // Handle all other IPv6 addresses

    // first run to find the longest contiguous zero words
    for (word = 0; word < 8; word++) {
      if (parts[word] === 0) {
        if (word - lastzero > 1) {
          len = 0;
        }
        lastzero = word;
        len++;
      }
      if (len > longest) {
        longest = len;
        zstart = word - longest + 1;
      }
    }

    for (word = 0; word < 8; word++) {
      if (longest > 1) {
        // compress contiguous zeros - to produce "::"
        if (parts[word] === 0 && word >= zstart && word < (zstart + longest) ) {
          if (word === zstart) {
            str += ":";
            if (zstart === 0) str += ":"; //leading zeros case
          }
          continue;
        }
      }
      // converts 16-bit words from big-endian to little-endian before converting to hex string
      str += Number(_ntohs(parts[word] & 0xffff)).toString(16);
      str += word < 7 ? ":" : "";
    }
    return str;
  },
  _inet_ntop6__deps: ['__setErrNo', '$ERRNO_CODES', '_inet_ntop6_raw'],
  _inet_ntop6: function(src, dst, size) {
    var addr = [
      {{{ makeGetValue('src', '0', 'i32') }}}, {{{ makeGetValue('src', '4', 'i32') }}},
      {{{ makeGetValue('src', '8', 'i32') }}}, {{{ makeGetValue('src', '12', 'i32') }}}
    ];
    var str = __inet_ntop6_raw(addr);
    if (str.length+1 > size) {
      ___setErrNo(ERRNO_CODES.ENOSPC);
      return 0;
    }
    writeStringToMemory(str, dst);
    return dst;
  },
  inet_ntop__deps: ['__setErrNo', '$ERRNO_CODES', '_inet_ntop4', '_inet_ntop6'],
  inet_ntop: function(af, src, dst, size) {
    // http://pubs.opengroup.org/onlinepubs/9699919799/functions/inet_ntop.html
    switch (af) {
      case {{{ cDefine('AF_INET') }}}:
        return __inet_ntop4(src, dst, size);
      case {{{ cDefine('AF_INET6') }}}:
        return __inet_ntop6(src, dst, size);
      default:
        ___setErrNo(ERRNO_CODES.EAFNOSUPPORT);
        return 0;
    }
  },

  _inet_pton4_raw: function(str) {
    var b = str.split('.');
    for (var i = 0; i < 4; i++) {
      var tmp = Number(b[i]);
      if (isNaN(tmp)) return null;
      b[i] = tmp;
    }
    return (b[0] | (b[1] << 8) | (b[2] << 16) | (b[3] << 24)) >>> 0;
  },
  _inet_pton4__deps: ['_inet_pton4_raw'],
  _inet_pton4: function(src, dst) {
    var ret = __inet_pton4_raw(Pointer_stringify(src));
    if (ret === null) {
      return 0;
    }
    {{{ makeSetValue('dst', '0', 'ret', 'i32') }}};
    return 1;
  },
  _inet_pton6_raw__deps: ['htons'],
  _inet_pton6_raw: function(str) {
    var words;
    var w, offset, z, i;
    /* http://home.deds.nl/~aeron/regex/ */
    var valid6regx = /^((?=.*::)(?!.*::.+::)(::)?([\dA-F]{1,4}:(:|\b)|){5}|([\dA-F]{1,4}:){6})((([\dA-F]{1,4}((?!\3)::|:\b|$))|(?!\2\3)){2}|(((2[0-4]|1\d|[1-9])?\d|25[0-5])\.?\b){4})$/i
    var parts = [];
    if (!valid6regx.test(str)) {
      return null;
    }
    if (str === "::") {
      return [0, 0, 0, 0, 0, 0, 0, 0];
    }
    // Z placeholder to keep track of zeros when splitting the string on ":"
    if (str.indexOf("::") === 0) {
      str = str.replace("::", "Z:"); // leading zeros case
    } else {
      str = str.replace("::", ":Z:");
    }

    if (str.indexOf(".") > 0) {
      // parse IPv4 embedded stress
      str = str.replace(new RegExp('[.]', 'g'), ":");
      words = str.split(":");
      words[words.length-4] = parseInt(words[words.length-4]) + parseInt(words[words.length-3])*256;
      words[words.length-3] = parseInt(words[words.length-2]) + parseInt(words[words.length-1])*256;
      words = words.slice(0, words.length-2);
    } else {
      words = str.split(":");
    }

    offset = 0; z = 0;
    for (w=0; w < words.length; w++) {
      if (typeof words[w] === 'string') {
        if (words[w] === 'Z') {
          // compressed zeros - write appropriate number of zero words
          for (z = 0; z < (8 - words.length+1); z++) {
            parts[w+z] = 0;
          }
          offset = z-1;
        } else {
          // parse hex to field to 16-bit value and write it in network byte-order
          parts[w+offset] = _htons(parseInt(words[w],16));
        }
      } else {
        // parsed IPv4 words
        parts[w+offset] = words[w];
      }
    }
    return [
      (parts[1] << 16) | parts[0],
      (parts[3] << 16) | parts[2],
      (parts[5] << 16) | parts[4],
      (parts[7] << 16) | parts[6]
    ];
  },
  _inet_pton6__deps: ['_inet_pton6_raw'],
  _inet_pton6: function(src, dst) {
    var ints = __inet_pton6_raw(Pointer_stringify(src));
    if (ints === null) {
      return 0;
    }
    for (var i = 0; i < 4; i++) {
      {{{ makeSetValue('dst', 'i*4', 'ints[i]', 'i32') }}};
    }
    return 1;
  },
  inet_pton__deps: ['__setErrNo', '$ERRNO_CODES', '_inet_pton4', '_inet_pton6'],
  inet_pton: function(af, src, dst) {
    // http://pubs.opengroup.org/onlinepubs/9699919799/functions/inet_pton.html
    switch (af) {
      case {{{ cDefine('AF_INET') }}}:
        return __inet_pton4(src, dst);
      case {{{ cDefine('AF_INET6') }}}:
        return __inet_pton6(src, dst);
      default:
        ___setErrNo(ERRNO_CODES.EAFNOSUPPORT);
        return -1;
    }
  },

  // ==========================================================================
  // net/if.h
  // ==========================================================================

  if_nametoindex: function(a) {
    return 0;
  },
  if_indextoname: function(a, b) {
    return 0;
  },
  if_nameindex: function() {
    return 0;
  },
  if_freenameindex: function(a) {
  },

  // ==========================================================================
  // netinet/in.h
  // ==========================================================================

  in6addr_any:
    'allocate([0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0], "i8", ALLOC_STATIC)',
  in6addr_loopback:
    'allocate([0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1], "i8", ALLOC_STATIC)',

  // ==========================================================================
  // netdb.h
  // ==========================================================================

  __h_errno_state: 'allocate(1, "i32", ALLOC_STATIC)',
  __h_errno_location__deps: ['__h_errno_state'],
  __h_errno_location: function() {
    return ___h_errno_state;
  },

  // We can't actually resolve hostnames in the browser, so instead
  // we're generating fake IP addresses with lookup_name that we can
  // resolve later on with lookup_addr.
  // We do the aliasing in 172.29.*.*, giving us 65536 possibilities.
  $DNS__deps: ['_inet_pton4_raw', '_inet_pton6_raw'],
  $DNS: {
    address_map: {
      id: 1,
      addrs: {},
      names: {}
    },

    lookup_name: function (name) {
      // If the name is already a valid ipv4 / ipv6 address, don't generate a fake one.
      var res = __inet_pton4_raw(name);
      if (res) {
        return name;
      }
      res = __inet_pton6_raw(name);
      if (res) {
        return name;
      }

      // See if this name is already mapped.
      var addr;

      if (DNS.address_map.addrs[name]) {
        addr = DNS.address_map.addrs[name];
      } else {
        var id = DNS.address_map.id++;
        assert(id < 65535, 'exceeded max address mappings of 65535');

        addr = '172.29.' + (id & 0xff) + '.' + (id & 0xff00);

        DNS.address_map.names[addr] = name;
        DNS.address_map.addrs[name] = addr;
      }

      return addr;
    },

    lookup_addr: function (addr) {
      if (DNS.address_map.names[addr]) {
        return DNS.address_map.names[addr];
      }

      return null;
    }
  },

  // note: lots of leaking here!
  gethostbyaddr__deps: ['$DNS', 'gethostbyname', '_inet_ntop4_raw'],
  gethostbyaddr: function (addr, addrlen, type) {
    if (type !== {{{ cDefine('AF_INET') }}}) {
      ___setErrNo(ERRNO_CODES.EAFNOSUPPORT);
      // TODO: set h_errno
      return null;
    }
    addr = {{{ makeGetValue('addr', '0', 'i32') }}}; // addr is in_addr
    var host = __inet_ntop4_raw(addr);
    var lookup = DNS.lookup_addr(host);
    if (lookup) {
      host = lookup;
    }
    var hostp = allocate(intArrayFromString(host), 'i8', ALLOC_STACK);
    return _gethostbyname(hostp);
  },

  gethostbyname__deps: ['$DNS', '_inet_pton4_raw'],
  gethostbyname: function(name) {
    name = Pointer_stringify(name);

    // generate hostent
    var ret = _malloc({{{ C_STRUCTS.hostent.__size__ }}}); // XXX possibly leaked, as are others here
    var nameBuf = _malloc(name.length+1);
    writeStringToMemory(name, nameBuf);
    {{{ makeSetValue('ret', C_STRUCTS.hostent.h_name, 'nameBuf', 'i8*') }}};
    var aliasesBuf = _malloc(4);
    {{{ makeSetValue('aliasesBuf', '0', '0', 'i8*') }}};
    {{{ makeSetValue('ret', C_STRUCTS.hostent.h_aliases, 'aliasesBuf', 'i8**') }}};
    var afinet = {{{ cDefine('AF_INET') }}};
    {{{ makeSetValue('ret', C_STRUCTS.hostent.h_addrtype, 'afinet', 'i32') }}};
    {{{ makeSetValue('ret', C_STRUCTS.hostent.h_length, '4', 'i32') }}};
    var addrListBuf = _malloc(12);
    {{{ makeSetValue('addrListBuf', '0', 'addrListBuf+8', 'i32*') }}};
    {{{ makeSetValue('addrListBuf', '4', '0', 'i32*') }}};
    {{{ makeSetValue('addrListBuf', '8', '__inet_pton4_raw(DNS.lookup_name(name))', 'i32') }}};
    {{{ makeSetValue('ret', C_STRUCTS.hostent.h_addr_list, 'addrListBuf', 'i8**') }}};
    return ret;
  },

  gethostbyname_r__deps: ['gethostbyname'],
  gethostbyname_r: function(name, ret, buf, buflen, out, err) {
    var data = _gethostbyname(name);
    _memcpy(ret, data, {{{ C_STRUCTS.hostent.__size__ }}});
    _free(data);
    {{{ makeSetValue('err', '0', '0', 'i32') }}};
    {{{ makeSetValue('out', '0', 'ret', '*') }}};
    return 0;
  },

  getaddrinfo__deps: ['$Sockets', '$DNS', '_inet_pton4_raw', '_inet_ntop4_raw', '_inet_pton6_raw', '_inet_ntop6_raw', '_write_sockaddr', 'htonl'],
  getaddrinfo: function(node, service, hint, out) {
    // Note getaddrinfo currently only returns a single addrinfo with ai_next defaulting to NULL. When NULL
    // hints are specified or ai_family set to AF_UNSPEC or ai_socktype or ai_protocol set to 0 then we
    // really should provide a linked list of suitable addrinfo values.
    var addrs = [];
    var canon = null;
    var addr = 0;
    var port = 0;
    var flags = 0;
    var family = {{{ cDefine('AF_UNSPEC') }}};
    var type = 0;
    var proto = 0;
    var ai, last;

    function allocaddrinfo(family, type, proto, canon, addr, port) {
      var sa, salen, ai;
      var res;

      salen = family === {{{ cDefine('AF_INET6') }}} ?
        {{{ C_STRUCTS.sockaddr_in6.__size__ }}} :
        {{{ C_STRUCTS.sockaddr_in.__size__ }}};
      addr = family === {{{ cDefine('AF_INET6') }}} ?
        __inet_ntop6_raw(addr) :
        __inet_ntop4_raw(addr);
      sa = _malloc(salen);
      res = __write_sockaddr(sa, family, addr, port);
      assert(!res.errno);

      ai = _malloc({{{ C_STRUCTS.addrinfo.__size__ }}});
      {{{ makeSetValue('ai', C_STRUCTS.addrinfo.ai_family, 'family', 'i32') }}};
      {{{ makeSetValue('ai', C_STRUCTS.addrinfo.ai_socktype, 'type', 'i32') }}};
      {{{ makeSetValue('ai', C_STRUCTS.addrinfo.ai_protocol, 'proto', 'i32') }}};
      if (canon) {
        {{{ makeSetValue('ai', C_STRUCTS.addrinfo.ai_canonname, 'canon', 'i32') }}};
      }
      {{{ makeSetValue('ai', C_STRUCTS.addrinfo.ai_addr, 'sa', '*') }}};
      if (family === {{{ cDefine('AF_INET6') }}}) {
        {{{ makeSetValue('ai', C_STRUCTS.addrinfo.ai_addrlen, C_STRUCTS.sockaddr_in6.__size__, 'i32') }}};
      } else {
        {{{ makeSetValue('ai', C_STRUCTS.addrinfo.ai_addrlen, C_STRUCTS.sockaddr_in.__size__, 'i32') }}};
      }
      {{{ makeSetValue('ai', C_STRUCTS.addrinfo.ai_next, '0', 'i32') }}};

      return ai;
    }

    if (hint) {
      flags = {{{ makeGetValue('hint', C_STRUCTS.addrinfo.ai_flags, 'i32') }}};
      family = {{{ makeGetValue('hint', C_STRUCTS.addrinfo.ai_family, 'i32') }}};
      type = {{{ makeGetValue('hint', C_STRUCTS.addrinfo.ai_socktype, 'i32') }}};
      proto = {{{ makeGetValue('hint', C_STRUCTS.addrinfo.ai_protocol, 'i32') }}};
    }
    if (type && !proto) {
      proto = type === {{{ cDefine('SOCK_DGRAM') }}} ? {{{ cDefine('IPPROTO_UDP') }}} : {{{ cDefine('IPPROTO_TCP') }}};
    }
    if (!type && proto) {
      type = proto === {{{ cDefine('IPPROTO_UDP') }}} ? {{{ cDefine('SOCK_DGRAM') }}} : {{{ cDefine('SOCK_STREAM') }}};
    }

    // If type or proto are set to zero in hints we should really be returning multiple addrinfo values, but for
    // now default to a TCP STREAM socket so we can at least return a sensible addrinfo given NULL hints.
    if (proto === 0) {
      proto = {{{ cDefine('IPPROTO_TCP') }}};
    }
    if (type === 0) {
      type = {{{ cDefine('SOCK_STREAM') }}};
    }

    if (!node && !service) {
      return {{{ cDefine('EAI_NONAME') }}};
    }
    if (flags & ~({{{ cDefine('AI_PASSIVE') }}}|{{{ cDefine('AI_CANONNAME') }}}|{{{ cDefine('AI_NUMERICHOST') }}}|
        {{{ cDefine('AI_NUMERICSERV') }}}|{{{ cDefine('AI_V4MAPPED') }}}|{{{ cDefine('AI_ALL') }}}|{{{ cDefine('AI_ADDRCONFIG') }}})) {
      return {{{ cDefine('EAI_BADFLAGS') }}};
    }
    if (hint !== 0 && ({{{ makeGetValue('hint', C_STRUCTS.addrinfo.ai_flags, 'i32') }}} & {{{ cDefine('AI_CANONNAME') }}}) && !node) {
      return {{{ cDefine('EAI_BADFLAGS') }}};
    }
    if (flags & {{{ cDefine('AI_ADDRCONFIG') }}}) {
      // TODO
      return {{{ cDefine('EAI_NONAME') }}};
    }
    if (type !== 0 && type !== {{{ cDefine('SOCK_STREAM') }}} && type !== {{{ cDefine('SOCK_DGRAM') }}}) {
      return {{{ cDefine('EAI_SOCKTYPE') }}};
    }
    if (family !== {{{ cDefine('AF_UNSPEC') }}} && family !== {{{ cDefine('AF_INET') }}} && family !== {{{ cDefine('AF_INET6') }}}) {
      return {{{ cDefine('EAI_FAMILY') }}};
    }

    if (service) {
      service = Pointer_stringify(service);
      port = parseInt(service, 10);

      if (isNaN(port)) {
        if (flags & {{{ cDefine('AI_NUMERICSERV') }}}) {
          return {{{ cDefine('EAI_NONAME') }}};
        }
        // TODO support resolving well-known service names from:
        // http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.txt
        return {{{ cDefine('EAI_SERVICE') }}};
      }
    }

    if (!node) {
      if (family === {{{ cDefine('AF_UNSPEC') }}}) {
        family = {{{ cDefine('AF_INET') }}};
      }
      if ((flags & {{{ cDefine('AI_PASSIVE') }}}) === 0) {
        if (family === {{{ cDefine('AF_INET') }}}) {
          addr = _htonl({{{ cDefine('INADDR_LOOPBACK') }}});
        } else {
          addr = [0, 0, 0, 1];
        }
      }
      ai = allocaddrinfo(family, type, proto, null, addr, port);
      {{{ makeSetValue('out', '0', 'ai', '*') }}};
      return 0;
    }

    //
    // try as a numeric address
    //
    node = Pointer_stringify(node);
    addr = __inet_pton4_raw(node);
    if (addr !== null) {
      // incoming node is a valid ipv4 address
      if (family === {{{ cDefine('AF_UNSPEC') }}} || family === {{{ cDefine('AF_INET') }}}) {
        family = {{{ cDefine('AF_INET') }}};
      }
      else if (family === {{{ cDefine('AF_INET6') }}} && (flags & {{{ cDefine('AI_V4MAPPED') }}})) {
        addr = [0, 0, _htonl(0xffff), addr];
        family = {{{ cDefine('AF_INET6') }}};
      } else {
        return {{{ cDefine('EAI_NONAME') }}};
      }
    } else {
      addr = __inet_pton6_raw(node);
      if (addr !== null) {
        // incoming node is a valid ipv6 address
        if (family === {{{ cDefine('AF_UNSPEC') }}} || family === {{{ cDefine('AF_INET6') }}}) {
          family = {{{ cDefine('AF_INET6') }}};
        } else {
          return {{{ cDefine('EAI_NONAME') }}};
        }
      }
    }
    if (addr != null) {
      ai = allocaddrinfo(family, type, proto, node, addr, port);
      {{{ makeSetValue('out', '0', 'ai', '*') }}};
      return 0;
    }
    if (flags & {{{ cDefine('AI_NUMERICHOST') }}}) {
      return {{{ cDefine('EAI_NONAME') }}};
    }

    //
    // try as a hostname
    //
    // resolve the hostname to a temporary fake address
    node = DNS.lookup_name(node);
    addr = __inet_pton4_raw(node);
    if (family === {{{ cDefine('AF_UNSPEC') }}}) {
      family = {{{ cDefine('AF_INET') }}};
    } else if (family === {{{ cDefine('AF_INET6') }}}) {
      addr = [0, 0, _htonl(0xffff), addr];
    }
    ai = allocaddrinfo(family, type, proto, null, addr, port);
    {{{ makeSetValue('out', '0', 'ai', '*') }}};
    return 0;
  },

  freeaddrinfo__deps: ['$Sockets'],
  freeaddrinfo: function(ai) {
    var sa = {{{ makeGetValue('ai', C_STRUCTS.addrinfo.ai_addr, '*') }}};
    _free(sa);
    _free(ai);
  },

  getnameinfo__deps: ['$Sockets', '$DNS', '_read_sockaddr'],
  getnameinfo: function (sa, salen, node, nodelen, serv, servlen, flags) {
    var info = __read_sockaddr(sa, salen);
    if (info.errno) {
      return {{{ cDefine('EAI_FAMILY') }}};
    }
    var port = info.port;
    var addr = info.addr;

    if (node && nodelen) {
      var lookup;
      if ((flags & {{{ cDefine('NI_NUMERICHOST') }}}) || !(lookup = DNS.lookup_addr(addr))) {
        if (flags & {{{ cDefine('NI_NAMEREQD') }}}) {
          return {{{ cDefine('EAI_NONAME') }}};
        }
      } else {
        addr = lookup;
      }
      if (addr.length >= nodelen) {
        return {{{ cDefine('EAI_OVERFLOW') }}};
      }
      writeStringToMemory(addr, node);
    }

    if (serv && servlen) {
      port = '' + port;
      if (port.length > servlen) {
        return {{{ cDefine('EAI_OVERFLOW') }}};
      }
      writeStringToMemory(port, serv);
    }

    return 0;
  },
  // Can't use a literal for $GAI_ERRNO_MESSAGES as was done for $ERRNO_MESSAGES as the keys (e.g. EAI_BADFLAGS)
  // are actually negative numbers and you can't have expressions as keys in JavaScript literals.
  $GAI_ERRNO_MESSAGES: {},

  gai_strerror__deps: ['$GAI_ERRNO_MESSAGES'],
  gai_strerror: function(val) {
    var buflen = 256;

    // On first call to gai_strerror we initialise the buffer and populate the error messages.
    if (!_gai_strerror.buffer) {
        _gai_strerror.buffer = _malloc(buflen);

        GAI_ERRNO_MESSAGES['0'] = 'Success';
        GAI_ERRNO_MESSAGES['' + {{{ cDefine('EAI_BADFLAGS') }}}] = 'Invalid value for \'ai_flags\' field';
        GAI_ERRNO_MESSAGES['' + {{{ cDefine('EAI_NONAME') }}}] = 'NAME or SERVICE is unknown';
        GAI_ERRNO_MESSAGES['' + {{{ cDefine('EAI_AGAIN') }}}] = 'Temporary failure in name resolution';
        GAI_ERRNO_MESSAGES['' + {{{ cDefine('EAI_FAIL') }}}] = 'Non-recoverable failure in name res';
        GAI_ERRNO_MESSAGES['' + {{{ cDefine('EAI_FAMILY') }}}] = '\'ai_family\' not supported';
        GAI_ERRNO_MESSAGES['' + {{{ cDefine('EAI_SOCKTYPE') }}}] = '\'ai_socktype\' not supported';
        GAI_ERRNO_MESSAGES['' + {{{ cDefine('EAI_SERVICE') }}}] = 'SERVICE not supported for \'ai_socktype\'';
        GAI_ERRNO_MESSAGES['' + {{{ cDefine('EAI_MEMORY') }}}] = 'Memory allocation failure';
        GAI_ERRNO_MESSAGES['' + {{{ cDefine('EAI_SYSTEM') }}}] = 'System error returned in \'errno\'';
        GAI_ERRNO_MESSAGES['' + {{{ cDefine('EAI_OVERFLOW') }}}] = 'Argument buffer overflow';
    }

    var msg = 'Unknown error';

    if (val in GAI_ERRNO_MESSAGES) {
      if (GAI_ERRNO_MESSAGES[val].length > buflen - 1) {
        msg = 'Message too long'; // EMSGSIZE message. This should never occur given the GAI_ERRNO_MESSAGES above. 
      } else {
        msg = GAI_ERRNO_MESSAGES[val];
      }
    }

    writeAsciiToMemory(msg, _gai_strerror.buffer);
    return _gai_strerror.buffer;
  },

  // Implement netdb.h protocol entry (getprotoent, getprotobyname, getprotobynumber, setprotoent, endprotoent)
  // http://pubs.opengroup.org/onlinepubs/9699919799/functions/getprotobyname.html
  // The Protocols object holds our 'fake' protocols 'database'.
  $Protocols: {
    list: [],
    map: {}
  },
  setprotoent__deps: ['$Protocols'],
  setprotoent: function(stayopen) {
    // void setprotoent(int stayopen);

    // Allocate and populate a protoent structure given a name, protocol number and array of aliases
    function allocprotoent(name, proto, aliases) {
      // write name into buffer
      var nameBuf = _malloc(name.length + 1);
      writeAsciiToMemory(name, nameBuf);

      // write aliases into buffer
      var j = 0;
      var length = aliases.length;
      var aliasListBuf = _malloc((length + 1) * 4); // Use length + 1 so we have space for the terminating NULL ptr.

      for (var i = 0; i < length; i++, j += 4) {
        var alias = aliases[i];
        var aliasBuf = _malloc(alias.length + 1);
        writeAsciiToMemory(alias, aliasBuf);
        {{{ makeSetValue('aliasListBuf', 'j', 'aliasBuf', 'i8*') }}};
      }
      {{{ makeSetValue('aliasListBuf', 'j', '0', 'i8*') }}}; // Terminating NULL pointer.

      // generate protoent
      var pe = _malloc({{{ C_STRUCTS.protoent.__size__ }}});
      {{{ makeSetValue('pe', C_STRUCTS.protoent.p_name, 'nameBuf', 'i8*') }}};
      {{{ makeSetValue('pe', C_STRUCTS.protoent.p_aliases, 'aliasListBuf', 'i8**') }}};
      {{{ makeSetValue('pe', C_STRUCTS.protoent.p_proto, 'proto', 'i32') }}};
      return pe;
    };

    // Populate the protocol 'database'. The entries are limited to tcp and udp, though it is fairly trivial
    // to add extra entries from /etc/protocols if desired - though not sure if that'd actually be useful.
    var list = Protocols.list;
    var map  = Protocols.map;
    if (list.length === 0) {
        var entry = allocprotoent('tcp', 6, ['TCP']);
        list.push(entry);
        map['tcp'] = map['6'] = entry;
        entry = allocprotoent('udp', 17, ['UDP']);
        list.push(entry);
        map['udp'] = map['17'] = entry;
    }

    _setprotoent.index = 0;
  },

  endprotoent: function() {
    // void endprotoent(void);
    // We're not using a real protocol database so we don't do a real close.
  },

  getprotoent__deps: ['setprotoent', '$Protocols'],
  getprotoent: function(number) {
    // struct protoent *getprotoent(void);
    // reads the  next  entry  from  the  protocols 'database' or return NULL if 'eof'
    if (_setprotoent.index === Protocols.list.length) {
      return 0; 
    } else {
      var result = Protocols.list[_setprotoent.index++];
      return result;
    }
  },

  getprotobyname__deps: ['setprotoent', '$Protocols'],
  getprotobyname: function(name) {
    // struct protoent *getprotobyname(const char *);
    name = Pointer_stringify(name);
    _setprotoent(true);
    var result = Protocols.map[name];
    return result;
  },

  getprotobynumber__deps: ['setprotoent', '$Protocols'],
  getprotobynumber: function(number) {
    // struct protoent *getprotobynumber(int proto);
    _setprotoent(true);
    var result = Protocols.map[number];
    return result;
  },

  // ==========================================================================
  // sockets. Note that the implementation assumes all sockets are always
  // nonblocking
  // ==========================================================================
#if SOCKET_WEBRTC
  $Sockets__deps: ['__setErrNo', '$ERRNO_CODES',
    function() { return 'var SocketIO = ' + read('socket.io.js') + ';\n' },
    function() { return 'var Peer = ' + read('wrtcp.js') + ';\n' }],
#else
  $Sockets__deps: ['__setErrNo', '$ERRNO_CODES'],
#endif
  $Sockets: {
    BUFFER_SIZE: 10*1024, // initial size
    MAX_BUFFER_SIZE: 10*1024*1024, // maximum size we will grow the buffer

    nextFd: 1,
    fds: {},
    nextport: 1,
    maxport: 65535,
    peer: null,
    connections: {},
    portmap: {},
    localAddr: 0xfe00000a, // Local address is always 10.0.0.254
    addrPool: [            0x0200000a, 0x0300000a, 0x0400000a, 0x0500000a,
               0x0600000a, 0x0700000a, 0x0800000a, 0x0900000a, 0x0a00000a,
               0x0b00000a, 0x0c00000a, 0x0d00000a, 0x0e00000a] /* 0x0100000a is reserved */
  },

#if SOCKET_WEBRTC
  /* WebRTC sockets supports several options on the Module object.

     * Module['host']: true if this peer is hosting, false otherwise
     * Module['webrtc']['broker']: hostname for the p2p broker that this peer should use
     * Module['webrtc']['session']: p2p session for that this peer will join, or undefined if this peer is hosting
     * Module['webrtc']['hostOptions']: options to pass into p2p library if this peer is hosting
     * Module['webrtc']['onpeer']: function(peer, route), invoked when this peer is ready to connect
     * Module['webrtc']['onconnect']: function(peer), invoked when a new peer connection is ready
     * Module['webrtc']['ondisconnect']: function(peer), invoked when an existing connection is closed
     * Module['webrtc']['onerror']: function(error), invoked when an error occurs
   */
  socket__deps: ['$FS', '$Sockets'],
  socket: function(family, type, protocol) {
    var INCOMING_QUEUE_LENGTH = 64;
    var info = FS.createStream({
      addr: null,
      port: null,
      inQueue: new CircularBuffer(INCOMING_QUEUE_LENGTH),
      header: new Uint16Array(2),
      bound: false,
      socket: true,
      stream_ops: {}
    });
    assert(info.fd < 64); // select() assumes socket fd values are in 0..63
    var stream = type == {{{ cDefine('SOCK_STREAM') }}};
    if (protocol) {
      assert(stream == (protocol == {{{ cDefine('IPPROTO_TCP') }}})); // if stream, must be tcp
    }

    // Open the peer connection if we don't have it already
    if (null == Sockets.peer) {
      var host = Module['host'];
      var broker = Module['webrtc']['broker'];
      var session = Module['webrtc']['session'];
      var peer = new Peer(broker);
      var listenOptions = Module['webrtc']['hostOptions'] || {};
      peer.onconnection = function peer_onconnection(connection) {
        console.log('connected');
        var addr;
        /* If this peer is connecting to the host, assign 10.0.0.1 to the host so it can be
           reached at a known address.
         */
        // Assign 10.0.0.1 to the host
        if (session && session === connection['route']) {
          addr = 0x0100000a; // 10.0.0.1
        } else {
          addr = Sockets.addrPool.shift();
        }
        connection['addr'] = addr;
        Sockets.connections[addr] = connection;
        connection.ondisconnect = function connection_ondisconnect() {
          console.log('disconnect');
          // Don't return the host address (10.0.0.1) to the pool
          if (!(session && session === Sockets.connections[addr]['route'])) {
            Sockets.addrPool.push(addr);
          }
          delete Sockets.connections[addr];

          if (Module['webrtc']['ondisconnect'] && 'function' === typeof Module['webrtc']['ondisconnect']) {
            Module['webrtc']['ondisconnect'](peer);
          }
        };
        connection.onerror = function connection_onerror(error) {
          if (Module['webrtc']['onerror'] && 'function' === typeof Module['webrtc']['onerror']) {
            Module['webrtc']['onerror'](error);
          }
        };
        connection.onmessage = function connection_onmessage(label, message) {
          if ('unreliable' === label) {
            handleMessage(addr, message.data);
          }
        }

        if (Module['webrtc']['onconnect'] && 'function' === typeof Module['webrtc']['onconnect']) {
          Module['webrtc']['onconnect'](peer);
        }
      };
      peer.onpending = function peer_onpending(pending) {
        console.log('pending from: ', pending['route'], '; initiated by: ', (pending['incoming']) ? 'remote' : 'local');
      };
      peer.onerror = function peer_onerror(error) {
        console.error(error);
      };
      peer.onroute = function peer_onroute(route) {
        if (Module['webrtc']['onpeer'] && 'function' === typeof Module['webrtc']['onpeer']) {
          Module['webrtc']['onpeer'](peer, route);
        }
      };
      function handleMessage(addr, message) {
#if SOCKET_DEBUG
        Module.print("received " + message.byteLength + " raw bytes");
#endif
        var header = new Uint16Array(message, 0, 2);
        if (Sockets.portmap[header[1]]) {
          Sockets.portmap[header[1]].inQueue.push([addr, message]);
        } else {
          console.log("unable to deliver message: ", addr, header[1], message);
        }
      }
      window.onbeforeunload = function window_onbeforeunload() {
        var ids = Object.keys(Sockets.connections);
        ids.forEach(function(id) {
          Sockets.connections[id].close();
        });
      }
      Sockets.peer = peer;
    }

    function CircularBuffer(max_length) {
      var buffer = new Array(++ max_length);
      var head = 0;
      var tail = 0;
      var length = 0;

      return {
        push: function(element) {
          buffer[tail ++] = element;
          length = Math.min(++ length, max_length - 1);
          tail = tail % max_length;
          if (tail === head) {
            head = (head + 1) % max_length;
          }
        },
        shift: function(element) {
          if (length < 1) return undefined;

          var element = buffer[head];
          -- length;
          head = (head + 1) % max_length;
          return element;
        },
        length: function() {
          return length;
        }
      };
    };
    return info.fd;
  },

  mkport__deps: ['$Sockets'],
  mkport: function() {
    for(var i = 0; i < Sockets.maxport; ++ i) {
      var port = Sockets.nextport ++;
      Sockets.nextport = (Sockets.nextport > Sockets.maxport) ? 1 : Sockets.nextport;
      if (!Sockets.portmap[port]) {
        return port;
      }
    }
    assert(false, 'all available ports are in use!');
  },

  connect: function() {
    // Stub: connection-oriented sockets are not supported yet.
  },

  bind__deps: ['$FS', '$Sockets', '_inet_ntop4_raw', 'ntohs', 'mkport'],
  bind: function(fd, addr, addrlen) {
    var info = FS.getStream(fd);
    if (!info) return -1;
    if (addr) {
      info.port = _ntohs(getValue(addr + {{{ C_STRUCTS.sockaddr_in.sin_port }}}, 'i16'));
      // info.addr = getValue(addr + {{{ C_STRUCTS.sockaddr_in.sin_addr.s_addr }}}, 'i32');
    }
    if (!info.port) {
      info.port = _mkport();
    }
    info.addr = Sockets.localAddr; // 10.0.0.254
    info.host = __inet_ntop4_raw(info.addr);
    info.close = function info_close() {
      Sockets.portmap[info.port] = undefined;
    }
    Sockets.portmap[info.port] = info;
    console.log("bind: ", info.host, info.port);
    info.bound = true;
  },

  sendmsg__deps: ['$FS', '$Sockets', 'bind', '_inet_ntop4_raw', 'ntohs'],
  sendmsg: function(fd, msg, flags) {
    var info = FS.getStream(fd);
    if (!info) return -1;
    // if we are not connected, use the address info in the message
    if (!info.bound) {
      _bind(fd);
    }

    var name = {{{ makeGetValue('msg', C_STRUCTS.msghdr.msg_name, '*') }}};
    assert(name, 'sendmsg on non-connected socket, and no name/address in the message');
    var port = _ntohs(getValue(name + {{{ C_STRUCTS.sockaddr_in.sin_port }}}, 'i16'));
    var addr = getValue(name + {{{ C_STRUCTS.sockaddr_in.sin_addr.s_addr }}}, 'i32');
    var connection = Sockets.connections[addr];
    // var host = __inet_ntop4_raw(addr);

    if (!(connection && connection.connected)) {
      ___setErrNo(ERRNO_CODES.EWOULDBLOCK);
      return -1;
    }

    var iov = {{{ makeGetValue('msg', C_STRUCTS.msghdr.msg_iov, 'i8*') }}};
    var num = {{{ makeGetValue('msg', C_STRUCTS.msghdr.msg_iovlen, 'i32') }}};
#if SOCKET_DEBUG
    Module.print('sendmsg vecs: ' + num);
#endif
    var totalSize = 0;
    for (var i = 0; i < num; i++) {
      totalSize += {{{ makeGetValue('iov', '8*i + 4', 'i32') }}};
    }
    var data = new Uint8Array(totalSize);
    var ret = 0;
    for (var i = 0; i < num; i++) {
      var currNum = {{{ makeGetValue('iov', '8*i + 4', 'i32') }}};
#if SOCKET_DEBUG
    Module.print('sendmsg curr size: ' + currNum);
#endif
      if (!currNum) continue;
      var currBuf = {{{ makeGetValue('iov', '8*i', 'i8*') }}};
      data.set(HEAPU8.subarray(currBuf, currBuf+currNum), ret);
      ret += currNum;
    }

    info.header[0] = info.port; // src port
    info.header[1] = port; // dst port
#if SOCKET_DEBUG
    Module.print('sendmsg port: ' + info.header[0] + ' -> ' + info.header[1]);
    Module.print('sendmsg bytes: ' + data.length + ' | ' + Array.prototype.slice.call(data));
#endif
    var buffer = new Uint8Array(info.header.byteLength + data.byteLength);
    buffer.set(new Uint8Array(info.header.buffer));
    buffer.set(data, info.header.byteLength);

    connection.send('unreliable', buffer.buffer);
    return ret;
  },

  recvmsg__deps: ['$FS', '$Sockets', 'bind', '__setErrNo', '$ERRNO_CODES', 'htons'],
  recvmsg: function(fd, msg, flags) {
    var info = FS.getStream(fd);
    if (!info) return -1;
    // if we are not connected, use the address info in the message
    if (!info.port) {
      console.log('recvmsg on unbound socket');
      assert(false, 'cannot receive on unbound socket');
    }
    if (info.inQueue.length() == 0) {
      ___setErrNo(ERRNO_CODES.EWOULDBLOCK);
      return -1;
    }

    var entry = info.inQueue.shift();
    var addr = entry[0];
    var message = entry[1];
    var header = new Uint16Array(message, 0, info.header.length);
    var buffer = new Uint8Array(message, info.header.byteLength);

    var bytes = buffer.length;
#if SOCKET_DEBUG
    Module.print('recvmsg port: ' + header[1] + ' <- ' + header[0]);
    Module.print('recvmsg bytes: ' + bytes + ' | ' + Array.prototype.slice.call(buffer));
#endif
    // write source
    var name = {{{ makeGetValue('msg', C_STRUCTS.msghdr.msg_name, '*') }}};
    {{{ makeSetValue('name', C_STRUCTS.sockaddr_in.sin_addr.s_addr, 'addr', 'i32') }}};
    {{{ makeSetValue('name', C_STRUCTS.sockaddr_in.sin_port, '_htons(header[0])', 'i16') }}};
    // write data
    var ret = bytes;
    var iov = {{{ makeGetValue('msg', C_STRUCTS.msghdr.msg_iov, 'i8*') }}};
    var num = {{{ makeGetValue('msg', C_STRUCTS.msghdr.msg_iovlen, 'i32') }}};
    var bufferPos = 0;
    for (var i = 0; i < num && bytes > 0; i++) {
      var currNum = {{{ makeGetValue('iov', '8*i + 4', 'i32') }}};
#if SOCKET_DEBUG
      Module.print('recvmsg loop ' + [i, num, bytes, currNum]);
#endif
      if (!currNum) continue;
      currNum = Math.min(currNum, bytes); // XXX what should happen when we partially fill a buffer..?
      bytes -= currNum;
      var currBuf = {{{ makeGetValue('iov', '8*i', 'i8*') }}};
#if SOCKET_DEBUG
      Module.print('recvmsg call recv ' + currNum);
#endif
      HEAPU8.set(buffer.subarray(bufferPos, bufferPos + currNum), currBuf);
      bufferPos += currNum;
    }
    return ret;
  },

  shutdown__deps: ['$FS'],
  shutdown: function(fd, how) {
    var stream = FS.getStream(fd);
    if (!stream) return -1;
    stream.close();
    FS.closeStream(stream);
  },

  ioctl__deps: ['$FS'],
  ioctl: function(fd, request, varargs) {
    var info = FS.getStream(fd);
    if (!info) return -1;
    var bytes = 0;
    if (info.hasData()) {
      bytes = info.inQueue[0].length;
    }
    var dest = {{{ makeGetValue('varargs', '0', 'i32') }}};
    {{{ makeSetValue('dest', '0', 'bytes', 'i32') }}};
    return 0;
  },

  setsockopt: function(d, level, optname, optval, optlen) {
#if SOCKET_DEBUG
    console.log('ignoring setsockopt command');
#endif
    return 0;
  },

  accept__deps: ['$FS'],
  accept: function(fd, addr, addrlen) {
    // TODO: webrtc queued incoming connections, etc.
    // For now, the model is that bind does a connect, and we "accept" that one connection,
    // which has host:port the same as ours. We also return the same socket fd.
    var info = FS.getStream(fd);
    if (!info) return -1;
    if (addr) {
      setValue(addr + {{{ C_STRUCTS.sockaddr_in.sin_addr.s_addr }}}, info.addr, 'i32');
      setValue(addr + {{{ C_STRUCTS.sockaddr_in.sin_port }}}, info.port, 'i32');
      setValue(addrlen, {{{ C_STRUCTS.sockaddr_in.__size__ }}}, 'i32');
    }
    return fd;
  },

  select__deps: ['$FS'],
  select: function(nfds, readfds, writefds, exceptfds, timeout) {
    // readfds are supported,
    // writefds checks socket open status
    // exceptfds not supported
    // timeout is always 0 - fully async
    assert(!exceptfds);

    var errorCondition = 0;

    function canRead(info) {
      return info.inQueue.length() > 0;
    }

    function canWrite(info) {
      return true;
    }

    function checkfds(nfds, fds, can) {
      if (!fds) return 0;

      var bitsSet = 0;
      var dstLow  = 0;
      var dstHigh = 0;
      var srcLow  = {{{ makeGetValue('fds', 0, 'i32') }}};
      var srcHigh = {{{ makeGetValue('fds', 4, 'i32') }}};
      nfds = Math.min(64, nfds); // fd sets have 64 bits

      for (var fd = 0; fd < nfds; fd++) {
        var mask = 1 << (fd % 32), int_ = fd < 32 ? srcLow : srcHigh;
        if (int_ & mask) {
          // index is in the set, check if it is ready for read
          var info = FS.getStream(fd);
          if (info && can(info)) {
            // set bit
            fd < 32 ? (dstLow = dstLow | mask) : (dstHigh = dstHigh | mask);
            bitsSet++;
          }
        }
      }

      {{{ makeSetValue('fds', 0, 'dstLow', 'i32') }}};
      {{{ makeSetValue('fds', 4, 'dstHigh', 'i32') }}};
      return bitsSet;
    }

    var totalHandles = checkfds(nfds, readfds, canRead) + checkfds(nfds, writefds, canWrite);
    if (errorCondition) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    } else {
      return totalHandles;
    }
  },
#else
  // ==========================================================================
  // socket.h
  // ==========================================================================
  _read_sockaddr__deps: ['$Sockets', '_inet_ntop4_raw', '_inet_ntop6_raw'],
  _read_sockaddr: function (sa, salen) {
    // family / port offsets are common to both sockaddr_in and sockaddr_in6
    var family = {{{ makeGetValue('sa', C_STRUCTS.sockaddr_in.sin_family, 'i16') }}};
    var port = _ntohs({{{ makeGetValue('sa', C_STRUCTS.sockaddr_in.sin_port, 'i16') }}});
    var addr;

    switch (family) {
      case {{{ cDefine('AF_INET') }}}:
        if (salen !== {{{ C_STRUCTS.sockaddr_in.__size__ }}}) {
          return { errno: ERRNO_CODES.EINVAL };
        }
        addr = {{{ makeGetValue('sa', C_STRUCTS.sockaddr_in.sin_addr.s_addr, 'i32') }}};
        addr = __inet_ntop4_raw(addr);
        break;
      case {{{ cDefine('AF_INET6') }}}:
        if (salen !== {{{ C_STRUCTS.sockaddr_in6.__size__ }}}) {
          return { errno: ERRNO_CODES.EINVAL };
        }
        addr = [
          {{{ makeGetValue('sa', C_STRUCTS.sockaddr_in6.sin6_addr.__in6_union.__s6_addr+0, 'i32') }}},
          {{{ makeGetValue('sa', C_STRUCTS.sockaddr_in6.sin6_addr.__in6_union.__s6_addr+4, 'i32') }}},
          {{{ makeGetValue('sa', C_STRUCTS.sockaddr_in6.sin6_addr.__in6_union.__s6_addr+8, 'i32') }}},
          {{{ makeGetValue('sa', C_STRUCTS.sockaddr_in6.sin6_addr.__in6_union.__s6_addr+12, 'i32') }}}
        ];
        addr = __inet_ntop6_raw(addr);
        break;
      default:
        return { errno: ERRNO_CODES.EAFNOSUPPORT };
    }

    return { family: family, addr: addr, port: port };
  },
  _write_sockaddr__deps: ['$Sockets', '_inet_pton4_raw', '_inet_pton6_raw'],
  _write_sockaddr: function (sa, family, addr, port) {
    switch (family) {
      case {{{ cDefine('AF_INET') }}}:
        addr = __inet_pton4_raw(addr);
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in.sin_family, 'family', 'i16') }}};
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in.sin_addr.s_addr, 'addr', 'i32') }}};
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in.sin_port, '_htons(port)', 'i16') }}};
        break;
      case {{{ cDefine('AF_INET6') }}}:
        addr = __inet_pton6_raw(addr);
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in6.sin6_family, 'family', 'i32') }}};
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in6.sin6_addr.__in6_union.__s6_addr+0, 'addr[0]', 'i32') }}};
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in6.sin6_addr.__in6_union.__s6_addr+4, 'addr[1]', 'i32') }}};
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in6.sin6_addr.__in6_union.__s6_addr+8, 'addr[2]', 'i32') }}};
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in6.sin6_addr.__in6_union.__s6_addr+12, 'addr[3]', 'i32') }}};
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in6.sin6_port, '_htons(port)', 'i16') }}};
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in6.sin6_flowinfo, '0', 'i32') }}};
        {{{ makeSetValue('sa', C_STRUCTS.sockaddr_in6.sin6_scope_id, '0', 'i32') }}};
        break;
      default:
        return { errno: ERRNO_CODES.EAFNOSUPPORT };
    }
    // kind of lame, but let's match _read_sockaddr's interface
    return {};
  },

  socket__deps: ['$FS', '$SOCKFS'],
  socket: function(family, type, protocol) {
    var sock = SOCKFS.createSocket(family, type, protocol);
    assert(sock.stream.fd < 64); // select() assumes socket fd values are in 0..63
    return sock.stream.fd;
  },

  socketpair__deps: ['$ERRNO_CODES', '__setErrNo'],
  socketpair: function(domain, type, protocol, sv) {
    // int socketpair(int domain, int type, int protocol, int sv[2]);
    // http://pubs.opengroup.org/onlinepubs/009695399/functions/socketpair.html
    ___setErrNo(ERRNO_CODES.EOPNOTSUPP);
    return -1;
  },

  shutdown__deps: ['$SOCKFS', '$ERRNO_CODES', '__setErrNo'],
  shutdown: function(fd, how) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    _close(fd);
  },

  bind__deps: ['$FS', '$SOCKFS', '$DNS', '$ERRNO_CODES', '__setErrNo', '_read_sockaddr'],
  bind: function(fd, addrp, addrlen) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }

    var info = __read_sockaddr(addrp, addrlen);
    if (info.errno) {
      ___setErrNo(info.errno);
      return -1;
    }
    var port = info.port;
    var addr = DNS.lookup_addr(info.addr) || info.addr;

    try {
      sock.sock_ops.bind(sock, addr, port);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  connect__deps: ['$FS', '$SOCKFS', '$DNS', '$ERRNO_CODES', '__setErrNo', '_read_sockaddr'],
  connect: function(fd, addrp, addrlen) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }

    var info = __read_sockaddr(addrp, addrlen);
    if (info.errno) {
      ___setErrNo(info.errno);
      return -1;
    }
    var port = info.port;
    var addr = DNS.lookup_addr(info.addr) || info.addr;

    try {
      sock.sock_ops.connect(sock, addr, port);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  listen__deps: ['$FS', '$SOCKFS', '$ERRNO_CODES', '__setErrNo'],
  listen: function(fd, backlog) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    try {
      sock.sock_ops.listen(sock, backlog);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  accept__deps: ['$FS', '$SOCKFS', '$DNS', '$ERRNO_CODES', '__setErrNo', '_write_sockaddr'],
  accept: function(fd, addr, addrlen) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    try {
      var newsock = sock.sock_ops.accept(sock);
      if (addr) {
        var res = __write_sockaddr(addr, newsock.family, DNS.lookup_name(newsock.daddr), newsock.dport);
        assert(!res.errno);
      }
      return newsock.stream.fd;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  getsockname__deps: ['$FS', '$SOCKFS', '$DNS', '$ERRNO_CODES', '__setErrNo', '_write_sockaddr'],
  getsockname: function (fd, addr, addrlen) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    try {
      var info = sock.sock_ops.getname(sock);
      var res = __write_sockaddr(addr, sock.family, DNS.lookup_name(info.addr), info.port);
      assert(!res.errno);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  getpeername__deps: ['$FS', '$SOCKFS', '$DNS', '$ERRNO_CODES', '__setErrNo', '_write_sockaddr'],
  getpeername: function (fd, addr, addrlen) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    try {
      var info = sock.sock_ops.getname(sock, true);
      var res = __write_sockaddr(addr, sock.family, DNS.lookup_name(info.addr), info.port);
      assert(!res.errno);
      return 0;
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  send__deps: ['$SOCKFS', '$ERRNO_CODES', '__setErrNo', 'write'],
  send: function(fd, buf, len, flags) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    // TODO honor flags
    return _write(fd, buf, len);
  },

  recv__deps: ['$SOCKFS', '$ERRNO_CODES', '__setErrNo', 'read'],
  recv: function(fd, buf, len, flags) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    // TODO honor flags
    return _read(fd, buf, len);
  },

  sendto__deps: ['$FS', '$SOCKFS', '$DNS', '$ERRNO_CODES', '__setErrNo', '_read_sockaddr'],
  sendto: function(fd, message, length, flags, dest_addr, dest_len) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }

    // read the address and port to send to
    var info = __read_sockaddr(dest_addr, dest_len);
    if (info.errno) {
      ___setErrNo(info.errno);
      return -1;
    }
    var port = info.port;
    var addr = DNS.lookup_addr(info.addr) || info.addr;

    // send the message
    try {
      var slab = {{{ makeGetSlabs('message', 'i8', true) }}};
      return sock.sock_ops.sendmsg(sock, slab, message, length, addr, port);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  recvfrom__deps: ['$FS', '$SOCKFS', '$DNS', '$ERRNO_CODES', '__setErrNo', '_write_sockaddr'],
  recvfrom: function(fd, buf, len, flags, addr, addrlen) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }

    // read from the socket
    var msg;
    try {
      msg = sock.sock_ops.recvmsg(sock, len);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }

    if (!msg) {
      // socket is closed
      return 0;
    }

    // write the source address out
    if (addr) {
      var res = __write_sockaddr(addr, sock.family, DNS.lookup_name(msg.addr), msg.port);
      assert(!res.errno);
    }
    // write the buffer out
    HEAPU8.set(msg.buffer, buf);

    return msg.buffer.byteLength;
  },

  sendmsg__deps: ['$FS', '$SOCKFS', '$DNS', '$ERRNO_CODES', '__setErrNo', '_read_sockaddr'],
  sendmsg: function(fd, message, flags) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }

    var iov = {{{ makeGetValue('message', C_STRUCTS.msghdr.msg_iov, '*') }}};
    var num = {{{ makeGetValue('message', C_STRUCTS.msghdr.msg_iovlen, 'i32') }}};

    // read the address and port to send to
    var addr;
    var port;
    var name = {{{ makeGetValue('message', C_STRUCTS.msghdr.msg_name, '*') }}};
    var namelen = {{{ makeGetValue('message', C_STRUCTS.msghdr.msg_namelen, 'i32') }}};
    if (name) {
      var info = __read_sockaddr(name, namelen);
      if (info.errno) {
        ___setErrNo(info.errno);
        return -1;
      }
      port = info.port;
      addr = DNS.lookup_addr(info.addr) || info.addr;
    }

    // concatenate scatter-gather arrays into one message buffer
    var total = 0;
    for (var i = 0; i < num; i++) {
      total += {{{ makeGetValue('iov', '(' + C_STRUCTS.iovec.__size__ + ' * i) + ' + C_STRUCTS.iovec.iov_len, 'i32') }}};
    }
    var view = new Uint8Array(total);
    var offset = 0;
    for (var i = 0; i < num; i++) {
      var iovbase = {{{ makeGetValue('iov', '(' + C_STRUCTS.iovec.__size__ + ' * i) + ' + C_STRUCTS.iovec.iov_base, 'i8*') }}};
      var iovlen = {{{ makeGetValue('iov', '(' + C_STRUCTS.iovec.__size__ + ' * i) + ' + C_STRUCTS.iovec.iov_len, 'i32') }}};
      for (var j = 0; j < iovlen; j++) {  
        view[offset++] = {{{ makeGetValue('iovbase', 'j', 'i8') }}};
      }
    }

    // write the buffer
    try {
      return sock.sock_ops.sendmsg(sock, view, 0, total, addr, port);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },

  recvmsg__deps: ['$FS', '$SOCKFS', '$DNS', '$ERRNO_CODES', '__setErrNo', '_write_sockaddr'],
  recvmsg: function(fd, message, flags) {
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }

    var iov = {{{ makeGetValue('message', C_STRUCTS.msghdr.msg_iov, 'i8*') }}};
    var num = {{{ makeGetValue('message', C_STRUCTS.msghdr.msg_iovlen, 'i32') }}};

    // get the total amount of data we can read across all arrays
    var total = 0;
    for (var i = 0; i < num; i++) {
      total += {{{ makeGetValue('iov', '(' + C_STRUCTS.iovec.__size__ + ' * i) + ' + C_STRUCTS.iovec.iov_len, 'i32') }}};
    }

    // try to read total data
    var msg;
    try {
      msg = sock.sock_ops.recvmsg(sock, total);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }

    if (!msg) {
      // socket is closed
      return 0;
    }

    // TODO honor flags:
    // MSG_OOB
    // Requests out-of-band data. The significance and semantics of out-of-band data are protocol-specific.
    // MSG_PEEK
    // Peeks at the incoming message.
    // MSG_WAITALL
    // Requests that the function block until the full amount of data requested can be returned. The function may return a smaller amount of data if a signal is caught, if the connection is terminated, if MSG_PEEK was specified, or if an error is pending for the socket.

    // write the source address out
    var name = {{{ makeGetValue('message', C_STRUCTS.msghdr.msg_name, '*') }}};
    if (name) {
      var res = __write_sockaddr(name, sock.family, DNS.lookup_name(msg.addr), msg.port);
      assert(!res.errno);
    }
    // write the buffer out to the scatter-gather arrays
    var bytesRead = 0;
    var bytesRemaining = msg.buffer.byteLength;

    for (var i = 0; bytesRemaining > 0 && i < num; i++) {
      var iovbase = {{{ makeGetValue('iov', '(' + C_STRUCTS.iovec.__size__ + ' * i) + ' + C_STRUCTS.iovec.iov_base, 'i8*') }}};
      var iovlen = {{{ makeGetValue('iov', '(' + C_STRUCTS.iovec.__size__ + ' * i) + ' + C_STRUCTS.iovec.iov_len, 'i32') }}};
      if (!iovlen) {
        continue;
      }
      var length = Math.min(iovlen, bytesRemaining);
      var buf = msg.buffer.subarray(bytesRead, bytesRead + length);
      HEAPU8.set(buf, iovbase + bytesRead);
      bytesRead += length;
      bytesRemaining -= length;
    }

    // TODO set msghdr.msg_flags
    // MSG_EOR
    // End of record was received (if supported by the protocol).
    // MSG_OOB
    // Out-of-band data was received.
    // MSG_TRUNC
    // Normal data was truncated.
    // MSG_CTRUNC

    return bytesRead;
  },

  setsockopt: function(fd, level, optname, optval, optlen) {
#if SOCKET_DEBUG
    console.log('ignoring setsockopt command');
#endif
    return 0;
  },

  getsockopt__deps: ['$SOCKFS', '__setErrNo', '$ERRNO_CODES'],
  getsockopt: function(fd, level, optname, optval, optlen) {
    // int getsockopt(int sockfd, int level, int optname, void *optval, socklen_t *optlen);
    // http://pubs.opengroup.org/onlinepubs/000095399/functions/getsockopt.html
    // Minimal getsockopt aimed at resolving https://github.com/kripken/emscripten/issues/2211
    // so only supports SOL_SOCKET with SO_ERROR.
    var sock = SOCKFS.getSocket(fd);
    if (!sock) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }

    if (level === {{{ cDefine('SOL_SOCKET') }}}) {
      if (optname === {{{ cDefine('SO_ERROR') }}}) {
        {{{ makeSetValue('optval', 0, 'sock.error', 'i32') }}};
        {{{ makeSetValue('optlen', 0, 4, 'i32') }}};
        sock.error = null; // Clear the error (The SO_ERROR option obtains and then clears this field).
        return 0;
      } else {
        ___setErrNo(ERRNO_CODES.ENOPROTOOPT); // The option is unknown at the level indicated.
#if ASSERTIONS
        Runtime.warnOnce('getsockopt() returning an error as we currently only support optname SO_ERROR');
#endif
        return -1;
      }
    } else {
      ___setErrNo(ERRNO_CODES.ENOPROTOOPT); //The option is unknown at the level indicated.
#if ASSERTIONS
      Runtime.warnOnce('getsockopt() returning an error as we only support level SOL_SOCKET');
#endif
      return -1;
    }
  },

  mkport: function() { throw 'TODO' },

  // ==========================================================================
  // select.h
  // ==========================================================================

  select__deps: ['$FS', '__DEFAULT_POLLMASK'],
  select: function(nfds, readfds, writefds, exceptfds, timeout) {
    // readfds are supported,
    // writefds checks socket open status
    // exceptfds not supported
    // timeout is always 0 - fully async
    assert(nfds <= 64, 'nfds must be less than or equal to 64');  // fd sets have 64 bits
    assert(!exceptfds, 'exceptfds not supported');

    var total = 0;
    
    var srcReadLow = (readfds ? {{{ makeGetValue('readfds', 0, 'i32') }}} : 0),
        srcReadHigh = (readfds ? {{{ makeGetValue('readfds', 4, 'i32') }}} : 0);
    var srcWriteLow = (writefds ? {{{ makeGetValue('writefds', 0, 'i32') }}} : 0),
        srcWriteHigh = (writefds ? {{{ makeGetValue('writefds', 4, 'i32') }}} : 0);
    var srcExceptLow = (exceptfds ? {{{ makeGetValue('exceptfds', 0, 'i32') }}} : 0),
        srcExceptHigh = (exceptfds ? {{{ makeGetValue('exceptfds', 4, 'i32') }}} : 0);

    var dstReadLow = 0,
        dstReadHigh = 0;
    var dstWriteLow = 0,
        dstWriteHigh = 0;
    var dstExceptLow = 0,
        dstExceptHigh = 0;

    var allLow = (readfds ? {{{ makeGetValue('readfds', 0, 'i32') }}} : 0) |
                 (writefds ? {{{ makeGetValue('writefds', 0, 'i32') }}} : 0) |
                 (exceptfds ? {{{ makeGetValue('exceptfds', 0, 'i32') }}} : 0);
    var allHigh = (readfds ? {{{ makeGetValue('readfds', 4, 'i32') }}} : 0) |
                  (writefds ? {{{ makeGetValue('writefds', 4, 'i32') }}} : 0) |
                  (exceptfds ? {{{ makeGetValue('exceptfds', 4, 'i32') }}} : 0);

    function get(fd, low, high, val) {
      return (fd < 32 ? (low & val) : (high & val));
    }

    for (var fd = 0; fd < nfds; fd++) {
      var mask = 1 << (fd % 32);
      if (!(get(fd, allLow, allHigh, mask))) {
        continue;  // index isn't in the set
      }

      var stream = FS.getStream(fd);
      if (!stream) {
        ___setErrNo(ERRNO_CODES.EBADF);
        return -1;
      }

      var flags = ___DEFAULT_POLLMASK;

      if (stream.stream_ops.poll) {
        flags = stream.stream_ops.poll(stream);
      }

      if ((flags & {{{ cDefine('POLLIN') }}}) && get(fd, srcReadLow, srcReadHigh, mask)) {
        fd < 32 ? (dstReadLow = dstReadLow | mask) : (dstReadHigh = dstReadHigh | mask);
        total++;
      }
      if ((flags & {{{ cDefine('POLLOUT') }}}) && get(fd, srcWriteLow, srcWriteHigh, mask)) {
        fd < 32 ? (dstWriteLow = dstWriteLow | mask) : (dstWriteHigh = dstWriteHigh | mask);
        total++;
      }
      if ((flags & {{{ cDefine('POLLPRI') }}}) && get(fd, srcExceptLow, srcExceptHigh, mask)) {
        fd < 32 ? (dstExceptLow = dstExceptLow | mask) : (dstExceptHigh = dstExceptHigh | mask);
        total++;
      }
    }

    if (readfds) {
      {{{ makeSetValue('readfds', '0', 'dstReadLow', 'i32') }}};
      {{{ makeSetValue('readfds', '4', 'dstReadHigh', 'i32') }}};
    }
    if (writefds) {
      {{{ makeSetValue('writefds', '0', 'dstWriteLow', 'i32') }}};
      {{{ makeSetValue('writefds', '4', 'dstWriteHigh', 'i32') }}};
    }
    if (exceptfds) {
      {{{ makeSetValue('exceptfds', '0', 'dstExceptLow', 'i32') }}};
      {{{ makeSetValue('exceptfds', '4', 'dstExceptHigh', 'i32') }}};
    }
    
    return total;
  },

  // ==========================================================================
  // sys/ioctl.h
  // ==========================================================================

  ioctl__deps: ['$FS'],
  ioctl: function(fd, request, varargs) {
    var stream = FS.getStream(fd);
    if (!stream) {
      ___setErrNo(ERRNO_CODES.EBADF);
      return -1;
    }
    var arg = {{{ makeGetValue('varargs', '0', 'i32') }}};

    try {
      return FS.ioctl(stream, request, arg);
    } catch (e) {
      FS.handleFSError(e);
      return -1;
    }
  },
#endif

  // pty.h

  openpty: function() { throw 'openpty: TODO' },
  forkpty: function() { throw 'forkpty: TODO' },

  // grp.h

  initgroups: function() { throw 'initgroups: TODO' },

  // pwd.h

  getpwnam: function() { throw 'getpwnam: TODO' },
  setpwent: function() { throw 'setpwent: TODO' },
  getpwent: function() { throw 'getpwent: TODO' },
  endpwent: function() { throw 'endpwent: TODO' },

  // ==========================================================================
  // emscripten.h
  // ==========================================================================

  emscripten_run_script: function(ptr) {
    eval(Pointer_stringify(ptr));
  },

  emscripten_run_script_int: function(ptr) {
    return eval(Pointer_stringify(ptr))|0;
  },

  emscripten_run_script_string: function(ptr) {
    var s = eval(Pointer_stringify(ptr)) + '';
    var me = _emscripten_run_script_string;
    if (!me.bufferSize || me.bufferSize < s.length+1) {
      if (me.bufferSize) _free(me.buffer);
      me.bufferSize = s.length+1;
      me.buffer = _malloc(me.bufferSize);
    }
    writeStringToMemory(s, me.buffer);
    return me.buffer;
  },

  emscripten_random: function() {
    return Math.random();
  },

  emscripten_get_now: function() {
    if (!_emscripten_get_now.actual) {
      if (ENVIRONMENT_IS_NODE) {
        _emscripten_get_now.actual = function _emscripten_get_now_actual() {
          var t = process['hrtime']();
          return t[0] * 1e3 + t[1] / 1e6;
        }
      } else if (typeof dateNow !== 'undefined') {
        _emscripten_get_now.actual = dateNow;
      } else if (typeof self === 'object' && self['performance'] && typeof self['performance']['now'] === 'function') {
        _emscripten_get_now.actual = function _emscripten_get_now_actual() { return self['performance']['now'](); };
      } else if (typeof performance === 'object' && typeof performance['now'] === 'function') {
        _emscripten_get_now.actual = function _emscripten_get_now_actual() { return performance['now'](); };
      } else {
        _emscripten_get_now.actual = Date.now;
      }
    }
    return _emscripten_get_now.actual();
  },

  emscripten_get_now_res: function() { // return resolution of get_now, in nanoseconds
    if (ENVIRONMENT_IS_NODE) {
      return 1; // nanoseconds
    } else if (typeof dateNow !== 'undefined' ||
               ((ENVIRONMENT_IS_WEB || ENVIRONMENT_IS_WORKER) && self['performance'] && self['performance']['now'])) {
      return 1000; // microseconds (1/1000 of a millisecond)
    } else {
      return 1000*1000; // milliseconds
    }
  },

  emscripten_get_now_is_monotonic__deps: ['emscripten_get_now'],
  emscripten_get_now_is_monotonic: function() {
    // return whether emscripten_get_now is guaranteed monotonic; the Date.now
    // implementation is not :(
    return ENVIRONMENT_IS_NODE || (typeof dateNow !== 'undefined') ||
        ((ENVIRONMENT_IS_WEB || ENVIRONMENT_IS_WORKER) && self['performance'] && self['performance']['now']);
  },

  // Returns [parentFuncArguments, functionName, paramListName]
  _emscripten_traverse_stack: function(args) {
    if (!args || !args.callee || !args.callee.name) {
      return [null, '', ''];
    }

    var funstr = args.callee.toString();
    var funcname = args.callee.name;
    var str = '(';
    var first = true;
    for(i in args) {
      var a = args[i];
      if (!first) {
        str += ", ";
      }
      first = false;
      if (typeof a === 'number' || typeof a === 'string') {
        str += a;
      } else {
        str += '(' + typeof a + ')';
      }
    }
    str += ')';
    var caller = args.callee.caller;
    args = caller ? caller.arguments : [];
    if (first)
      str = '';
    return [args, funcname, str];
  },

  emscripten_get_callstack_js__deps: ['_emscripten_traverse_stack'],
  emscripten_get_callstack_js: function(flags) {
    var callstack = jsStackTrace();

    // Find the symbols in the callstack that corresponds to the functions that report callstack information, and remove everyhing up to these from the output.
    var iThisFunc = callstack.lastIndexOf('_emscripten_log');
    var iThisFunc2 = callstack.lastIndexOf('_emscripten_get_callstack');
    var iNextLine = callstack.indexOf('\n', Math.max(iThisFunc, iThisFunc2))+1;
    callstack = callstack.slice(iNextLine);

    // If user requested to see the original source stack, but no source map information is available, just fall back to showing the JS stack.
    if (flags & 8/*EM_LOG_C_STACK*/ && typeof emscripten_source_map === 'undefined') {
      Runtime.warnOnce('Source map information is not available, emscripten_log with EM_LOG_C_STACK will be ignored. Build with "--pre-js $EMSCRIPTEN/src/emscripten-source-map.min.js" linker flag to add source map loading to code.');
      flags ^= 8/*EM_LOG_C_STACK*/;
      flags |= 16/*EM_LOG_JS_STACK*/;
    }

    var stack_args = null;
    if (flags & 128 /*EM_LOG_FUNC_PARAMS*/) {
      // To get the actual parameters to the functions, traverse the stack via the unfortunately deprecated 'arguments.callee' method, if it works:
      var stack_args = __emscripten_traverse_stack(arguments);
      while (stack_args[1].indexOf('_emscripten_') >= 0)
        stack_args = __emscripten_traverse_stack(stack_args[0]);
    }
    
    // Process all lines:
    lines = callstack.split('\n');
    callstack = '';
    var newFirefoxRe = new RegExp('\\s*(.*?)@(.*?):([0-9]+):([0-9]+)'); // New FF30 with column info: extract components of form '       Object._main@http://server.com:4324:12'
    var firefoxRe = new RegExp('\\s*(.*?)@(.*):(.*)(:(.*))?'); // Old FF without column info: extract components of form '       Object._main@http://server.com:4324'
    var chromeRe = new RegExp('\\s*at (.*?) \\\((.*):(.*):(.*)\\\)'); // Extract components of form '    at Object._main (http://server.com/file.html:4324:12)'
    
    for(l in lines) {
      var line = lines[l];

      var jsSymbolName = '';
      var file = '';
      var lineno = 0;
      var column = 0;

      var parts = chromeRe.exec(line);
      if (parts && parts.length == 5) {
        jsSymbolName = parts[1];
        file = parts[2];
        lineno = parts[3];
        column = parts[4];
      } else {
        parts = newFirefoxRe.exec(line);
        if (!parts) parts = firefoxRe.exec(line);
        if (parts && parts.length >= 4) {
          jsSymbolName = parts[1];
          file = parts[2];
          lineno = parts[3];
          column = parts[4]|0; // Old Firefox doesn't carry column information, but in new FF30, it is present. See https://bugzilla.mozilla.org/show_bug.cgi?id=762556
        } else {
          // Was not able to extract this line for demangling/sourcemapping purposes. Output it as-is.
          callstack += line + '\n';
          continue;
        }
      }

      // Try to demangle the symbol, but fall back to showing the original JS symbol name if not available.
      var cSymbolName = (flags & 32/*EM_LOG_DEMANGLE*/) ? demangle(jsSymbolName) : jsSymbolName;
      if (!cSymbolName) {
        cSymbolName = jsSymbolName;
      }

      var haveSourceMap = false;

      if (flags & 8/*EM_LOG_C_STACK*/) {
        var orig = emscripten_source_map.originalPositionFor({line: lineno, column: column});
        haveSourceMap = (orig && orig.source);
        if (haveSourceMap) {
          if (flags & 64/*EM_LOG_NO_PATHS*/) {
            orig.source = orig.source.substring(orig.source.replace(/\\/g, "/").lastIndexOf('/')+1);
          }
          callstack += '    at ' + cSymbolName + ' (' + orig.source + ':' + orig.line + ':' + orig.column + ')\n';
        }
      }
      if ((flags & 16/*EM_LOG_JS_STACK*/) || !haveSourceMap) {
        if (flags & 64/*EM_LOG_NO_PATHS*/) {
          file = file.substring(file.replace(/\\/g, "/").lastIndexOf('/')+1);
        }
        callstack += (haveSourceMap ? ('     = '+jsSymbolName) : ('    at '+cSymbolName)) + ' (' + file + ':' + lineno + ':' + column + ')\n';
      }
      
      // If we are still keeping track with the callstack by traversing via 'arguments.callee', print the function parameters as well.
      if (flags & 128 /*EM_LOG_FUNC_PARAMS*/ && stack_args[0]) {
        if (stack_args[1] == jsSymbolName && stack_args[2].length > 0) {
          callstack = callstack.replace(/\s+$/, '');
          callstack += ' with values: ' + stack_args[1] + stack_args[2] + '\n';
        }
        stack_args = __emscripten_traverse_stack(stack_args[0]);
      }
    }
    // Trim extra whitespace at the end of the output.
    callstack = callstack.replace(/\s+$/, '');
    return callstack;
  },

  emscripten_get_callstack__deps: ['emscripten_get_callstack_js'],
  emscripten_get_callstack: function(flags, str, maxbytes) {
    var callstack = _emscripten_get_callstack_js(flags);
    // User can query the required amount of bytes to hold the callstack.
    if (!str || maxbytes <= 0) {
      return callstack.length+1;
    }
    // Truncate output to avoid writing past bounds.
    if (callstack.length > maxbytes-1) {
      callstack = callstack.slice(0, maxbytes-1);
    }
    // Output callstack string as C string to HEAP.
    writeStringToMemory(callstack, str, false);

    // Return number of bytes written.
    return callstack.length+1;
  },

  emscripten_log_js__deps: ['emscripten_get_callstack_js'],
  emscripten_log_js: function(flags, str) {
    if (flags & 24/*EM_LOG_C_STACK | EM_LOG_JS_STACK*/) {
      str = str.replace(/\s+$/, ''); // Ensure the message and the callstack are joined cleanly with exactly one newline.
      str += (str.length > 0 ? '\n' : '') + _emscripten_get_callstack_js(flags);
    }

    if (flags & 1 /*EM_LOG_CONSOLE*/) {
      if (flags & 4 /*EM_LOG_ERROR*/) {
        console.error(str);
      } else if (flags & 2 /*EM_LOG_WARN*/) {
        console.warn(str);
      } else {
        console.log(str);
      }
    } else if (flags & 6 /*EM_LOG_ERROR|EM_LOG_WARN*/) {
      Module.printErr(str);
    } else {
      Module.print(str);
    }
  },

  emscripten_log__deps: ['_formatString', 'emscripten_log_js'],
  emscripten_log: function(flags, varargs) {
    // Extract the (optionally-existing) printf format specifier field from varargs.
    var format = {{{ makeGetValue('varargs', '0', 'i32', undefined, undefined, true) }}};
    varargs += Math.max(Runtime.getNativeFieldSize('i32'), Runtime.getAlignSize('i32', null, true));
    var str = '';
    if (format) {
      var result = __formatString(format, varargs);
      for(var i = 0 ; i < result.length; ++i) {
        str += String.fromCharCode(result[i]);
      }
    }
    _emscripten_log_js(flags, str);
  },

  emscripten_get_compiler_setting: function(name) {
    name = Pointer_stringify(name);

    var ret = Runtime.getCompilerSetting(name);
    if (typeof ret === 'number') return ret;

    if (!_emscripten_get_compiler_setting.cache) _emscripten_get_compiler_setting.cache = {};
    var cache = _emscripten_get_compiler_setting.cache;
    var fullname = name + '__str';
    var fullret = cache[fullname];
    if (fullret) return fullret;
    return cache[fullname] = allocate(intArrayFromString(ret + ''), 'i8', ALLOC_NORMAL);
  },

  emscripten_debugger: function() {
    debugger;
  },

  //============================
  // i64 math
  //============================

  i64Add__asm: true,
  i64Add__sig: 'iiiii',
  i64Add: function(a, b, c, d) {
    /*
      x = a + b*2^32
      y = c + d*2^32
      result = l + h*2^32
    */
    a = a|0; b = b|0; c = c|0; d = d|0;
    var l = 0, h = 0;
    l = (a + c)>>>0;
    h = (b + d + (((l>>>0) < (a>>>0))|0))>>>0; // Add carry from low word to high word on overflow.
    {{{ makeStructuralReturn(['l|0', 'h'], true) }}};
  },
  llvm_uadd_with_overflow_i64__asm: true,
  llvm_uadd_with_overflow_i64__sig: 'iiiii',
  llvm_uadd_with_overflow_i64: function(a, b, c, d) {
    a = a|0; b = b|0; c = c|0; d = d|0;
    var l = 0, h = 0, overflow = 0;
    l = (a + c)>>>0;
    h = (b + d)>>>0;
    overflow = ((h>>>0) < (b>>>0))|0; // Return whether addition overflowed even the high word.
    if ((l>>>0) < (a>>>0)) {
      h = (h + 1)>>>0; // Add carry from low word to high word on overflow.
      overflow = overflow | (!h); // Check again for overflow.
    }
    {{{ makeStructuralReturn(['l|0', 'h', 'overflow'], true) }}};
  },

  i64Subtract__asm: true,
  i64Subtract__sig: 'iiiii',
  i64Subtract: function(a, b, c, d) {
    a = a|0; b = b|0; c = c|0; d = d|0;
    var l = 0, h = 0;
    l = (a - c)>>>0;
    h = (b - d)>>>0;
    h = (b - d - (((c>>>0) > (a>>>0))|0))>>>0; // Borrow one from high word to low word on underflow.
    {{{ makeStructuralReturn(['l|0', 'h'], true) }}};
  },

  bitshift64Shl__asm: true,
  bitshift64Shl__sig: 'iiii',
  bitshift64Shl: function(low, high, bits) {
    low = low|0; high = high|0; bits = bits|0;
    var ander = 0;
    if ((bits|0) < 32) {
      ander = ((1 << bits) - 1)|0;
      {{{ makeSetTempRet0('(high << bits) | ((low&(ander << (32 - bits))) >>> (32 - bits))') }}};
      return low << bits;
    }
    {{{ makeSetTempRet0('low << (bits - 32)') }}};
    return 0;
  },
  bitshift64Ashr__asm: true,
  bitshift64Ashr__sig: 'iiii',
  bitshift64Ashr: function(low, high, bits) {
    low = low|0; high = high|0; bits = bits|0;
    var ander = 0;
    if ((bits|0) < 32) {
      ander = ((1 << bits) - 1)|0;
      {{{ makeSetTempRet0('high >> bits') }}};
      return (low >>> bits) | ((high&ander) << (32 - bits));
    }
    {{{ makeSetTempRet0('(high|0) < 0 ? -1 : 0') }}};
    return (high >> (bits - 32))|0;
  },
  bitshift64Lshr__asm: true,
  bitshift64Lshr__sig: 'iiii',
  bitshift64Lshr: function(low, high, bits) {
    low = low|0; high = high|0; bits = bits|0;
    var ander = 0;
    if ((bits|0) < 32) {
      ander = ((1 << bits) - 1)|0;
      {{{ makeSetTempRet0('high >>> bits') }}};
      return (low >>> bits) | ((high&ander) << (32 - bits));
    }
    {{{ makeSetTempRet0('0') }}};
    return (high >>> (bits - 32))|0;
  },

  // misc shims for musl
  __lock: function() {},
  __unlock: function() {},
  __lockfile: function() { return 1 },
  __unlockfile: function(){},

  // ubsan (undefined behavior sanitizer) support
  __ubsan_handle_float_cast_overflow: function(id, post) {
    abort('Undefined behavior! ubsan_handle_float_cast_overflow: ' + [id, post]);
  },

  // misc definitions to avoid unnecessary unresolved symbols from fastcomp
  emscripten_prep_setjmp: true,
  emscripten_cleanup_setjmp: true,
  emscripten_check_longjmp: true,
  emscripten_get_longjmp_result: true,
  emscripten_setjmp: true,
  emscripten_preinvoke: true,
  emscripten_postinvoke: true,
  emscripten_resume: true,
  emscripten_landingpad: true,
  getHigh32: true,
  setHigh32: true,
  FtoILow: true,
  FtoIHigh: true,
  DtoILow: true,
  DtoIHigh: true,
  BDtoILow: true,
  BDtoIHigh: true,
  SItoF: true,
  UItoF: true,
  SItoD: true,
  UItoD: true,
  BItoD: true,
  llvm_dbg_value: true,
  llvm_ctlz_i32: true,
  emscripten_asm_const: true,
  emscripten_asm_const_int: true,
  emscripten_asm_const_double: true,
};

function autoAddDeps(object, name) {
  name = [name];
  for (var item in object) {
    if (item.substr(-6) != '__deps') {
      if (!object[item + '__deps']) {
        object[item + '__deps'] = name;
      } else {
        object[item + '__deps'].push(name[0]); // add to existing list
      }
    }
  }
}

// Add aborting stubs for various libc stuff needed by libc++
['pthread_cond_signal', 'pthread_equal', 'pthread_join', 'pthread_detach'].forEach(function(aborter) {
  LibraryManager.library[aborter] = function aborting_stub() { throw 'TODO: ' + aborter };
});