Quieter cab extraction

build/extract_from_cab.py

 #!/usr/bin/env python
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Extracts a single file from a CAB archive."""
 
 import os
 import shutil
 import subprocess
 import sys
 import tempfile
 
+def run_quiet(*args):
+  """Run 'expand' supressing noisy output. Returns returncode from process."""
+  popen = subprocess.Popen(args, stdout=subprocess.PIPE)
+  out, _ = popen.communicate()
+  if popen.returncode:
+    # expand emits errors to stdout, so if we fail, then print that out.
+    print out
+  return popen.returncode
 
 def main():
   if len(sys.argv) != 4:
     print 'Usage: extract_from_cab.py cab_path archived_file output_dir'
     return 1
 
   [cab_path, archived_file, output_dir] = sys.argv[1:]
 
   # Expand.exe does its work in a fixed-named temporary directory created within
   # the given output directory. This is a problem for concurrent extractions, so
   # create a unique temp dir within the desired output directory to work around
   # this limitation.
   temp_dir = tempfile.mkdtemp(dir=output_dir)
 
   try:
     # Invoke the Windows expand utility to extract the file.
-    level = subprocess.call(
-        ['expand', cab_path, '-F:' + archived_file, temp_dir])
+    level = run_quiet('expand', cab_path, '-F:' + archived_file, temp_dir)
     if level == 0:
       # Move the output file into place, preserving expand.exe's behavior of
       # paving over any preexisting file.
       output_file = os.path.join(output_dir, archived_file)
       try:
         os.remove(output_file)
       except OSError:
         pass
       os.rename(os.path.join(temp_dir, archived_file), output_file)
   finally:
     shutil.rmtree(temp_dir, True)
 
   if level != 0:
     return level
 
   # The expand utility preserves the modification date and time of the archived
   # file. Touch the extracted file. This helps build systems that compare the
   # modification times of input and output files to determine whether to do an
   # action.
   os.utime(os.path.join(output_dir, archived_file), None)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())