Delete before cp in download_from_google_storage

download_from_google_storage.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """Download files from Google Storage based on SHA1 sums."""
 
 
 import hashlib
 import optparse
@@ skipping 218 matching lines @@
         continue
     # Check if file exists.
     file_url = '%s/%s' % (base_url, input_sha1_sum)
     if gsutil.check_call('ls', file_url)[0] != 0:
       out_q.put('%d> File %s for %s does not exist, skipping.' % (
           thread_num, file_url, output_filename))
       ret_codes.put((1, 'File %s for %s does not exist.' % (
           file_url, output_filename)))
       continue
     # Fetch the file.
-    out_q.put('%d> Downloading %s...' % (
-        thread_num, output_filename))
+    out_q.put('%d> Downloading %s...' % (thread_num, output_filename))
+    try:
+      os.remove(output_filename)  # Delete the file if it exists already.
+    except OSError:
+      if os.path.exists(output_filename):
+        out_q.put('%d> Warning: deleting %s failed.' % (
+            thread_num, output_filename))
     code, _, err = gsutil.check_call('cp', '-q', file_url, output_filename)
     if code != 0:
       out_q.put('%d> %s' % (thread_num, err))
       ret_codes.put((code, err))
 
     # Set executable bit.
     if sys.platform == 'cygwin':
       # Under cygwin, mark all files as executable. The executable flag in
       # Google Storage will not be set when uploading from Windows, so if
       # this script is running under cygwin and we're downloading an
@@ skipping 207 matching lines @@
     return code
 
   return download_from_google_storage(
       input_filename, base_url, gsutil, options.num_threads, options.directory,
       options.recursive, options.force, options.output, options.ignore_errors,
       options.sha1_file, options.verbose, options.auto_platform)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))