webkit: expose webkit branch and revision number in about pages

build/util/lastchange.py

 #!/usr/bin/env python
 # Copyright (c) 2010 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.
 
 """
 lastchange.py -- Chromium revision fetching utility.
 """
 
 import optparse
 import os
 import re
 import subprocess
 import sys
 
 
-def FetchSVNRevision(command):
+def FetchSVNRevision(command, directory):
   """
-  Fetch the Subversion revision for the local tree.
+  Fetch the Subversion branch and revision for the a given directory
+  by running the given command (e.g. "svn info").
 
   Errors are swallowed.
+
+  Returns:
+    a tuple of (url, revision) or None on error.
   """
   try:
     proc = subprocess.Popen(command,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE,
+                            cwd=directory,
                             shell=(sys.platform=='win32'))
   except OSError:
     # command is apparently either not installed or not executable.
     return None
   if proc:
-    svn_re = re.compile('^Revision:\s+(\d+)', re.M)
-    match = svn_re.search(proc.stdout.read())
-    if match:
-      return match.group(1)
+    output = proc.stdout.read()
+    match = re.search('^Revision:\s+(\d+)', output, re.M)
+    if not match:
+      return None
+    revision = match.group(1)
+
+    match = re.search('^Repository Root:\s+(\S+)', output, re.M)
+    if not match:
+      return None
+    url = match.group(1)
+
+    return (url, revision)
+
   return None
 
 
-def FetchChange(default_lastchange):
+def FetchChange(default_lastchange, directory=None):
   """
-  Returns the last change, from some appropriate revision control system.
+  Returns the last change (in the form of a branch, revision tuple),
+  from some appropriate revision control system.
   """
-  change = FetchSVNRevision(['svn', 'info'])
+  change = FetchSVNRevision(['svn', 'info'], directory)
   if not change and sys.platform in ('linux2',):
-    change = FetchSVNRevision(['git', 'svn', 'info'])
+    change = FetchSVNRevision(['git', 'svn', 'info'], directory)
   if not change:
     if default_lastchange and os.path.exists(default_lastchange):
-      change = open(default_lastchange, 'r').read().strip()
+      revision = open(default_lastchange, 'r').read().strip()
+      change = (None, revision)
     else:
-      change = '0'
+      change = ('', '0')
   return change
 
 
 def WriteIfChanged(file_name, contents):
   """
   Writes the specified contents to the specified file_name
   iff the contents are different than the current contents.
   """
   try:
     old_contents = open(file_name, 'r').read()
@@ skipping 22 matching lines @@
   out_file = opts.output
 
   while len(args) and out_file is None:
     if out_file is None:
       out_file = args.pop(0)
   if args:
     sys.stderr.write('Unexpected arguments: %r\n\n' % args)
     parser.print_help()
     sys.exit(2)
 
-  change = FetchChange(opts.default_lastchange)
+  url, revision = FetchChange(opts.default_lastchange)
 
   if opts.revision_only:
-    print change
+    print revision
   else:
-    contents = "LASTCHANGE=%s\n" % change
+    contents = "LASTCHANGE=%s\n" % revision
     if out_file:
       WriteIfChanged(out_file, contents)
     else:
       sys.stdout.write(contents)
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())