mf_iocache2.c

/* Copyright (c) 2000, 2023, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   Without limiting anything contained in the foregoing, this file,
   which is part of C Driver for MySQL (Connector/C), is also subject to the
   Universal FOSS Exception, version 1.0, a copy of which can be found at
   http://oss.oracle.com/licenses/universal-foss-exception.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/*
  More functions to be used with IO_CACHE files
*/

#include "mysys_priv.h"
#include "my_sys.h"
#include <m_string.h>
#include <stdarg.h>
#include <m_ctype.h>

#include "mysql/psi/mysql_file.h"

/*
  Copy contents of an IO_CACHE to a file.

  SYNOPSIS
    my_b_copy_to_file()
    cache  IO_CACHE to copy from
    file   File to copy to

  DESCRIPTION
    Copy the contents of the cache to the file. The cache will be
    re-inited to a read cache and will read from the beginning of the
    cache.

    If a failure to write fully occurs, the cache is only copied
    partially.

  TODO
    Make this function solid by handling partial reads from the cache
    in a correct manner: it should be atomic.

  RETURN VALUE
    0  All OK
    1  An error occured
*/
int
my_b_copy_to_file(IO_CACHE *cache, FILE *file)
{
  size_t bytes_in_cache;
  DBUG_ENTER("my_b_copy_to_file");

  /* Reinit the cache to read from the beginning of the cache */
  if (reinit_io_cache(cache, READ_CACHE, 0L, FALSE, FALSE))
    DBUG_RETURN(1);
  bytes_in_cache= my_b_bytes_in_cache(cache);
  do
  {
    if (my_fwrite(file, cache->read_pos, bytes_in_cache,
                  MYF(MY_WME | MY_NABP)) == (size_t) -1)
      DBUG_RETURN(1);
    cache->read_pos= cache->read_end;
  } while ((bytes_in_cache= my_b_fill(cache)));
  if(cache->error == -1)
    DBUG_RETURN(1);
  DBUG_RETURN(0);
}


my_off_t my_b_append_tell(IO_CACHE* info)
{
  /*
    Sometimes we want to make sure that the variable is not put into
    a register in debugging mode so we can see its value in the core
  */
#ifndef NDEBUG
# define dbug_volatile volatile
#else
# define dbug_volatile
#endif

  /*
    Prevent optimizer from putting res in a register when debugging
    we need this to be able to see the value of res when the assert fails
  */
  dbug_volatile my_off_t res; 

  /*
    We need to lock the append buffer mutex to keep flush_io_cache()
    from messing with the variables that we need in order to provide the
    answer to the question.
  */
  mysql_mutex_lock(&info->append_buffer_lock);

#ifndef NDEBUG
  /*
    Make sure EOF is where we think it is. Note that we cannot just use
    my_tell() because we have a reader thread that could have left the
    file offset in a non-EOF location
  */
  {
    volatile my_off_t save_pos;
    save_pos = mysql_file_tell(info->file,MYF(0));
    mysql_file_seek(info->file,(my_off_t)0,MY_SEEK_END,MYF(0));
    /*
      Save the value of my_tell in res so we can see it when studying coredump
    */
    assert(info->end_of_file - (info->append_read_pos-info->write_buffer)
           == (res=mysql_file_tell(info->file,MYF(0))));
    mysql_file_seek(info->file,save_pos,MY_SEEK_SET,MYF(0));
  }
#endif  
  res = info->end_of_file + (info->write_pos-info->append_read_pos);
  mysql_mutex_unlock(&info->append_buffer_lock);
  return res;
}

my_off_t my_b_safe_tell(IO_CACHE *info)
{
  if (unlikely(info->type == SEQ_READ_APPEND))
    return my_b_append_tell(info);
  return my_b_tell(info);
}

/*
  Make next read happen at the given position
  For write cache, make next write happen at the given position
*/

void my_b_seek(IO_CACHE *info,my_off_t pos)
{
  my_off_t offset;
  DBUG_ENTER("my_b_seek");
  DBUG_PRINT("enter",("pos: %lu", (ulong) pos));

  /*
    TODO:
       Verify that it is OK to do seek in the non-append
       area in SEQ_READ_APPEND cache
     a) see if this always works
     b) see if there is a better way to make it work
  */
  if (info->type == SEQ_READ_APPEND)
    (void) flush_io_cache(info);

  offset=(pos - info->pos_in_file);

  if (info->type == READ_CACHE || info->type == SEQ_READ_APPEND)
  {
    /* TODO: explain why this works if pos < info->pos_in_file */
    if ((ulonglong) offset < (ulonglong) (info->read_end - info->buffer))
    {
      /* The read is in the current buffer; Reuse it */
      info->read_pos = info->buffer + offset;
      DBUG_VOID_RETURN;
    }
    else
    {
      /* Force a new read on next my_b_read */
      info->read_pos=info->read_end=info->buffer;
    }
  }
  else if (info->type == WRITE_CACHE)
  {
    /* If write is in current buffer, reuse it */
    if ((ulonglong) offset <=
	(ulonglong) (info->write_end - info->write_buffer))
    {
      info->write_pos = info->write_buffer + offset;
      DBUG_VOID_RETURN;
    }
    (void) flush_io_cache(info);
    /* Correct buffer end so that we write in increments of IO_SIZE */
    info->write_end=(info->write_buffer+info->buffer_length-
		     (pos & (IO_SIZE-1)));
  }
  info->pos_in_file=pos;
  info->seek_not_done=1;
  DBUG_VOID_RETURN;
}


/*
  Fill buffer of the cache.

  NOTES
    This assumes that you have already used all characters in the CACHE,
    independent of the read_pos value!

  RETURN
  0  On error or EOF (info->error = -1 on error)
  #  Number of characters
*/


size_t my_b_fill(IO_CACHE *info)
{
  my_off_t pos_in_file=(info->pos_in_file+
			(size_t) (info->read_end - info->buffer));
  size_t diff_length, length, max_length;

  if (info->seek_not_done)
  {					/* File touched, do seek */
    if (mysql_file_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0)) ==
	MY_FILEPOS_ERROR)
    {
      info->error= 0;
      return 0;
    }
    info->seek_not_done=0;
  }
  diff_length=(size_t) (pos_in_file & (IO_SIZE-1));
  max_length=(info->read_length-diff_length);
  if (max_length >= (info->end_of_file - pos_in_file))
    max_length= (size_t) (info->end_of_file - pos_in_file);

  if (!max_length)
  {
    info->error= 0;
    return 0;					/* EOF */
  }
  DBUG_EXECUTE_IF ("simulate_my_b_fill_error",
                   {DBUG_SET("+d,simulate_file_read_error");});
  if ((length= mysql_file_read(info->file,info->buffer,max_length,
                       info->myflags)) == (size_t) -1)
  {
    info->error= -1;
    return 0;
  }
  info->read_pos=info->buffer;
  info->read_end=info->buffer+length;
  info->pos_in_file=pos_in_file;
  return length;
}


/*
  Read a string ended by '\n' into a buffer of 'max_length' size.
  Returns number of characters read, 0 on error.
  last byte is set to '\0'
  If buffer is full then to[max_length-1] will be set to \0.
*/

size_t my_b_gets(IO_CACHE *info, char *to, size_t max_length)
{
  char *start = to;
  size_t length;
  max_length--;					/* Save place for end \0 */

  /* Calculate number of characters in buffer */
  if (!(length= my_b_bytes_in_cache(info)) &&
      !(length= my_b_fill(info)))
    return 0;

  for (;;)
  {
    uchar *pos, *end;
    if (length > max_length)
      length=max_length;
    for (pos=info->read_pos,end=pos+length ; pos < end ;)
    {
      if ((*to++ = *pos++) == '\n')
      {
	info->read_pos=pos;
	*to='\0';
	return (size_t) (to-start);
      }
    }
    if (!(max_length-=length))
    {
     /* Found enough charcters;  Return found string */
      info->read_pos=pos;
      *to='\0';
      return (size_t) (to-start);
    }
    if (!(length=my_b_fill(info)))
      return 0;
  }
}


my_off_t my_b_filelength(IO_CACHE *info)
{
  if (info->type == WRITE_CACHE)
    return my_b_tell(info);

  info->seek_not_done= 1;
  return mysql_file_seek(info->file, 0L, MY_SEEK_END, MYF(0));
}


/**
  Simple printf version. Used for logging in MySQL.
  Supports '%c', '%s', '%b', '%d', '%u', '%ld', '%lu' and '%llu'.
  Returns number of written characters, or (size_t) -1 on error.

  @param info           The IO_CACHE to write to
  @param fmt            format string
  @param ...            variable list of arguments
  @return               number of bytes written, -1 if an error occurred
*/

size_t my_b_printf(IO_CACHE *info, const char* fmt, ...)
{
  size_t result;
  va_list args;
  va_start(args,fmt);
  result=my_b_vprintf(info, fmt, args);
  va_end(args);
  return result;
}


/**
  Implementation of my_b_printf.

  @param info           The IO_CACHE to write to
  @param fmt            format string
  @param args           variable list of arguments
  @return               number of bytes written, -1 if an error occurred
*/

size_t my_b_vprintf(IO_CACHE *info, const char* fmt, va_list args)
{
  size_t out_length= 0;
  uint minimum_width; /* as yet unimplemented */
  uint minimum_width_sign;
  uint precision; /* as yet unimplemented for anything but %b */
  my_bool is_zero_padded;

  /*
    Store the location of the beginning of a format directive, for the
    case where we learn we shouldn't have been parsing a format string
    at all, and we don't want to lose the flag/precision/width/size
    information.
   */
  const char* backtrack;

  for (; *fmt != '\0'; fmt++)
  {
    /* Copy everything until '%' or end of string */
    const char *start=fmt;
    size_t length;
    
    for (; (*fmt != '\0') && (*fmt != '%'); fmt++) ;

    length= (size_t) (fmt - start);
    out_length+=length;
    if (my_b_write(info, (const uchar*) start, length))
      goto err;

    if (*fmt == '\0')				/* End of format */
      return out_length;

    /* 
      By this point, *fmt must be a percent;  Keep track of this location and
      skip over the percent character. 
    */
    assert(*fmt == '%');
    backtrack= fmt;
    fmt++;

    is_zero_padded= FALSE;
    minimum_width_sign= 1;
    minimum_width= 0;
    precision= 0;
    /* Skip if max size is used (to be compatible with printf) */

process_flags:
    switch (*fmt)
    {
      case '-': 
        minimum_width_sign= -1; fmt++; goto process_flags;
      case '0':
        is_zero_padded= TRUE; fmt++; goto process_flags;
      case '#':
        /** @todo Implement "#" conversion flag. */  fmt++; goto process_flags;
      case ' ':
        /** @todo Implement " " conversion flag. */  fmt++; goto process_flags;
      case '+':
        /** @todo Implement "+" conversion flag. */  fmt++; goto process_flags;
    }

    if (*fmt == '*')
    {
      minimum_width= (int) va_arg(args, int);
      fmt++;
    }
    else
    {
      while (my_isdigit(&my_charset_latin1, *fmt)) {
        minimum_width=(minimum_width * 10) + (*fmt - '0');
        fmt++;
      }
    }
    minimum_width*= minimum_width_sign;

    if (*fmt == '.')
    {
      fmt++;
      if (*fmt == '*') {
        precision= (int) va_arg(args, int);
        fmt++;
      }
      else
      {
        while (my_isdigit(&my_charset_latin1, *fmt)) {
          precision=(precision * 10) + (*fmt - '0');
          fmt++;
        }
      }
    }

    if (*fmt == 's')				/* String parameter */
    {
      char *par = va_arg(args, char *);
      size_t length2 = strlen(par);
      /* TODO: implement precision */
      out_length+= length2;
      if (my_b_write(info, (uchar*) par, length2))
	goto err;
    }
    else if (*fmt == 'c')                     /* char type parameter */
    {
      char par[2];
      par[0] = va_arg(args, int);
      out_length++;
      if (my_b_write(info, (uchar*) par, 1))
        goto err;
    }
    else if (*fmt == 'b')                       /* Sized buffer parameter, only precision makes sense */
    {
      char *par = va_arg(args, char *);
      out_length+= precision;
      if (my_b_write(info, (uchar*) par, precision))
        goto err;
    }
    else if (*fmt == 'd' || *fmt == 'u')	/* Integer parameter */
    {
      int iarg;
      size_t length2;
      char buff[32];

      iarg = va_arg(args, int);
      if (*fmt == 'd')
	length2= (size_t) (int10_to_str((long) iarg,buff, -10) - buff);
      else
        length2= (uint) (int10_to_str((long) (uint) iarg,buff,10)- buff);

      /* minimum width padding */
      if (minimum_width > length2) 
      {
        char *buffz;
                    
        buffz= my_alloca(minimum_width - length2);
        if (is_zero_padded)
          memset(buffz, '0', minimum_width - length2);
        else
          memset(buffz, ' ', minimum_width - length2);
        if (my_b_write(info, buffz, minimum_width - length2))
        {
          goto err;
        }
      }

      out_length+= length2;
      if (my_b_write(info, (uchar*) buff, length2))
	goto err;
    }
    else if ((*fmt == 'l' && fmt[1] == 'd') || fmt[1] == 'u')
      /* long parameter */
    {
      long iarg;
      size_t length2;
      char buff[32];

      iarg = va_arg(args, long);
      if (*++fmt == 'd')
	length2= (size_t) (int10_to_str(iarg,buff, -10) - buff);
      else
	length2= (size_t) (int10_to_str(iarg,buff,10)- buff);
      out_length+= length2;
      if (my_b_write(info, (uchar*) buff, length2))
	goto err;
    }
    else if (fmt[0] == 'l' && fmt[1] == 'l' && fmt[2] == 'u')
    {
      ulonglong iarg;
      size_t length2;
      char buff[32];

      iarg = va_arg(args, ulonglong);
      length2= (size_t) (longlong10_to_str(iarg, buff, 10) - buff);
      out_length+= length2;
      fmt+= 2;
      if (my_b_write(info, (uchar *) buff, length2))
        goto err;
    }
    else
    {
      /* %% or unknown code */
      if (my_b_write(info, (uchar*) backtrack, (size_t) (fmt-backtrack)))
        goto err;
      out_length+= fmt-backtrack;
    }
  }
  return out_length;

err:
  return (size_t) -1;
}