utils.py

# Copyright 2020 The Emscripten Authors.  All rights reserved.
# Emscripten is available under two separate licenses, the MIT license and the
# University of Illinois/NCSA Open Source License.  Both these licenses can be
# found in the LICENSE file.

import contextlib
import os
import shutil
import sys
from pathlib import Path

from . import diagnostics

__rootpath__ = os.path.abspath(os.path.dirname(os.path.dirname(__file__)))
WINDOWS = sys.platform.startswith('win')
MACOS = sys.platform == 'darwin'
LINUX = sys.platform.startswith('linux')


def exit_with_error(msg, *args):
  diagnostics.error(msg, *args)


def path_from_root(*pathelems):
  return str(Path(__rootpath__, *pathelems))


def safe_ensure_dirs(dirname):
  os.makedirs(dirname, exist_ok=True)


@contextlib.contextmanager
def chdir(dir):
  """A context manager that performs actions in the given directory."""
  orig_cwd = os.getcwd()
  os.chdir(dir)
  try:
    yield
  finally:
    os.chdir(orig_cwd)


# Finds the given executable 'program' in PATH. Operates like the Unix tool 'which'.
def which(program):
  def is_exe(fpath):
    return os.path.isfile(fpath) and os.access(fpath, os.X_OK)

  if os.path.isabs(program):
    if os.path.isfile(program):
      return program

    if WINDOWS:
      for suffix in ['.exe', '.cmd', '.bat']:
        if is_exe(program + suffix):
          return program + suffix

  fpath, fname = os.path.split(program)
  if fpath:
    if is_exe(program):
      return program
  else:
    for path in os.environ["PATH"].split(os.pathsep):
      path = path.strip('"')
      exe_file = os.path.join(path, program)
      if is_exe(exe_file):
        return exe_file
      if WINDOWS:
        for suffix in ('.exe', '.cmd', '.bat'):
          if is_exe(exe_file + suffix):
            return exe_file + suffix

  return None


def read_file(file_path):
  """Read from a file opened in text mode"""
  with open(file_path, encoding='utf-8') as fh:
    return fh.read()


def read_binary(file_path):
  """Read from a file opened in binary mode"""
  with open(file_path, 'rb') as fh:
    return fh.read()


def write_file(file_path, text):
  """Write to a file opened in text mode"""
  with open(file_path, 'w', encoding='utf-8') as fh:
    fh.write(text)


def write_binary(file_path, contents):
  """Write to a file opened in binary mode"""
  with open(file_path, 'wb') as fh:
    fh.write(contents)


def delete_file(filename):
  """Delete a file (if it exists)."""
  if not os.path.exists(filename):
    return
  os.remove(filename)


def delete_dir(dirname):
  """Delete a directory (if it exists)."""
  if not os.path.exists(dirname):
    return
  shutil.rmtree(dirname)


def delete_contents(dirname, exclude=None):
  """Delete the contents of a directory without removing
  the directory itself."""
  if not os.path.exists(dirname):
    return
  for entry in os.listdir(dirname):
    if exclude and entry in exclude:
      continue
    entry = os.path.join(dirname, entry)
    if os.path.isdir(entry):
      delete_dir(entry)
    else:
      delete_file(entry)