Patch path filtering script.

scripts/slave/apply_svn_patch.py

 #!/usr/bin/python
 # Copyright 2013 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.
 
 import optparse
 import subprocess
 import sys
 
 
 def main():
   parser = optparse.OptionParser()
   parser.add_option('-p', '--patch-url',
                     help='The SVN URL to download the patch from.')
   parser.add_option('-r', '--root-dir',
                     help='The root dir in which to apply patch.')
+  parser.add_option('', '--filter-script',
+                    help=('Path to a Python script to be used to manipulate '
+                          'the contents of the patch. One example could be to '
+                          'remove parts of the patch matching certain file '
+                          'paths. The script must use stdin for input and '
+                          'stdout for output. The script will get the '
+                          '--root-dir flag passed on to it. To pass additional '
+                          'flags; use: -- --flag1 --flag2'))
+  parser.add_option('', '--strip-level', type='int', default=0,
+                    help=('The number of path components to be stripped from '
+                          'the filenames in the patch. Default: %default.'))
 
   options, args = parser.parse_args()
-  if args:
+  if args and not options.filter_script:
     parser.error('Unused args: %s' % args)
+
   if not (options.patch_url and options.root_dir):
     parser.error('A patch URL and root directory should be specified.')
 
   svn_cat = subprocess.Popen(['svn', 'cat', options.patch_url],
                              stdout=subprocess.PIPE)
-  patch = subprocess.Popen(['patch', '-t', '-p', '0', '-d', options.root_dir],
-                           stdin=svn_cat.stdout)
+  patch_input = svn_cat.stdout
+  if options.filter_script:
+    extra_args = args or []
+    filtering = subprocess.Popen([sys.executable, options.filter_script,
+                                  '--root-dir', options.root_dir] + extra_args,
+                                 stdin=svn_cat.stdout, stdout=subprocess.PIPE,
+                                 stderr=sys.stdout)
+    patch_input = filtering.stdout
+  patch = subprocess.Popen(['patch', '-t', '-p', str(options.strip_level),
+                            '-d', options.root_dir],
+                           stdin=patch_input)
 
   _, err = patch.communicate()
   return err or None
 
 
 if __name__ == '__main__':
   sys.exit(main())