1#!/usr/bin/env python
2# Copyright (c) 2012 The Chromium Authors. All rights reserved.
3# Use of this source code is governed by a BSD-style license that can be
4# found in the LICENSE file.
5
6"""Extracts a single file from a CAB archive."""
7
8import os
9import shutil
10import subprocess
11import sys
12import tempfile
13
14def run_quiet(*args):
15  """Run 'expand' suppressing noisy output. Returns returncode from process."""
16  popen = subprocess.Popen(args, stdout=subprocess.PIPE)
17  out, _ = popen.communicate()
18  if popen.returncode:
19    # expand emits errors to stdout, so if we fail, then print that out.
20    print out
21  return popen.returncode
22
23def main():
24  if len(sys.argv) != 4:
25    print 'Usage: extract_from_cab.py cab_path archived_file output_dir'
26    return 1
27
28  [cab_path, archived_file, output_dir] = sys.argv[1:]
29
30  # Expand.exe does its work in a fixed-named temporary directory created within
31  # the given output directory. This is a problem for concurrent extractions, so
32  # create a unique temp dir within the desired output directory to work around
33  # this limitation.
34  temp_dir = tempfile.mkdtemp(dir=output_dir)
35
36  try:
37    # Invoke the Windows expand utility to extract the file.
38    level = run_quiet('expand', cab_path, '-F:' + archived_file, temp_dir)
39    if level == 0:
40      # Move the output file into place, preserving expand.exe's behavior of
41      # paving over any preexisting file.
42      output_file = os.path.join(output_dir, archived_file)
43      try:
44        os.remove(output_file)
45      except OSError:
46        pass
47      os.rename(os.path.join(temp_dir, archived_file), output_file)
48  finally:
49    shutil.rmtree(temp_dir, True)
50
51  if level != 0:
52    return level
53
54  # The expand utility preserves the modification date and time of the archived
55  # file. Touch the extracted file. This helps build systems that compare the
56  # modification times of input and output files to determine whether to do an
57  # action.
58  os.utime(os.path.join(output_dir, archived_file), None)
59  return 0
60
61
62if __name__ == '__main__':
63  sys.exit(main())
64