Given git hash, get SVN revision(if available) or Commit position.

tools/auto_bisect/source_control.py

 # Copyright 2014 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.
 
 """This module contains the SourceControl class and related functions."""
 
 import os
+import re
 
 from . import bisect_utils
 
 CROS_VERSION_PATTERN = 'new version number from %s'
 
 
 def DetermineAndCreateSourceControl(opts):
   """Attempts to determine the underlying source control workflow and returns
   a SourceControl object.
 
@@ skipping 177 matching lines @@
 
     Returns:
       True if the current branch on src is 'master'
     """
     cmd = ['rev-parse', '--abbrev-ref', 'HEAD']
     log_output = bisect_utils.CheckRunGit(cmd)
     log_output = log_output.strip()
 
     return log_output == "master"
 
-  def SVNFindRev(self, revision, cwd=None):
-    """Maps directly to the 'git svn find-rev' command.
+  def SVNFindRev(self, git_revision, cwd=None):
+    """Finds a SVN revision OR git number for the given git hash.
+
+    If "git svn find_rev <hash>" fails, then it runs
+    "git log --format=%b -1 origin/master <hash> and greps for
+    Cr-Commit-Position.
 
     Args:
-      revision: The git SHA1 to use.
+      git_revision: The git SHA1 to use.
 
     Returns:
-      An integer changelist #, otherwise None.
+      Git number (aka git commit position) OR an SVN revision as integer,
+      otherwise None.
     """
 
-    cmd = ['svn', 'find-rev', revision]
+    cmd = ['svn', 'find-rev', git_revision]
 
     output = bisect_utils.CheckRunGit(cmd, cwd)
     svn_revision = output.strip()
 
     if bisect_utils.IsStringInt(svn_revision):
       return int(svn_revision)
 
+    # Retrieve commit position number from git log body for the given revision.
+    # TODO(prasadv): Use an appropriate command to find commit position instead
+    # of parsing the log. Resolve this once 407316 is fixed.
+    commit_position_pattern = 'Cr-Commit-Position: .*@\{#(?P<commit>[0-9]+)\}'
+    cmd = ['log', '--format=%b', '-1', 'origin/master', git_revision]
+    output = bisect_utils.CheckRunGit(cmd, cwd=cwd)
+    if output:
+      version_re = re.compile(commit_position_pattern)
+      commit_reg = version_re.search(output)
+      if commit_reg and bisect_utils.IsStringInt(commit_reg.group('commit')):
+        return int(commit_reg.group('commit'))
+
     return None
 
   def QueryRevisionInfo(self, revision, cwd=None):
     """Gathers information on a particular revision, such as author's name,
     email, subject, and date.
 
     Args:
       revision: Revision you want to gather information on.
 
     Returns:
@@ skipping 47 matching lines @@
         revision_end: End of revision range.
 
     Returns:
         Returns a list of commits that touched this file.
     """
     cmd = ['log', '--format=%H', '%s~1..%s' % (revision_start, revision_end),
            '--', filename]
     output = bisect_utils.CheckRunGit(cmd)
 
     return [o for o in output.split('\n') if o]