build/extract_from_cab.py

   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
   8 import os
   9 import shutil
  10 import subprocess
  11 import sys
  12 import tempfile
  13
  14 def run_quiet(*args):
  15   """Run 'expand' supressing 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
  23 def 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
  62 if __name__ == '__main__':
  63   sys.exit(main())