Add lots of utils, PRESUBMIT.py

py/utils/git_utils.py

Index: py/utils/git_utils.py
diff --git a/py/utils/git_utils.py b/py/utils/git_utils.py
new file mode 100644
index 0000000000000000000000000000000000000000..da7f0976ef2dc07852fd506a11d5bc9c9d6085c7
--- /dev/null
+++ b/py/utils/git_utils.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+# Copyright (c) 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 functions for using git."""
+
+
+import os
+import shell_utils
+
+
+GIT = 'git.bat' if os.name == 'nt' else 'git'
+
+
+def Add(addition):
+  """Run 'git add <addition>'"""
+  shell_utils.run([GIT, 'add', addition])
+
+def AIsAncestorOfB(a, b):
+  """Return true if a is an ancestor of b."""
+  return shell_utils.run([GIT, 'merge-base', a, b]).rstrip() == FullHash(a)
+
+def FullHash(commit):
+  """Return full hash of specified commit."""
+  return shell_utils.run([GIT, 'rev-parse', '--verify', commit]).rstrip()
+
+def IsMerge(commit):
+  """Return True if the commit is a merge, False otherwise."""
+  rev_parse = shell_utils.run([GIT, 'rev-parse', commit, '--max-count=1',
+                               '--no-merges'])
+  last_non_merge = rev_parse.split('\n')[0]
+  # Get full hash since that is what was returned by rev-parse.
+  return FullHash(commit) != last_non_merge
+
+def MergeAbort():
+  """Abort in process merge."""
+  shell_utils.run([GIT, 'merge', '--abort'])
+
+def ShortHash(commit):
+  """Return short hash of the specified commit."""
+  return shell_utils.run([GIT, 'show', commit, '--format=%h', '-s']).rstrip()
+
+def GetRemoteMasterHash(git_url):
+  return shell_utils.run([GIT, 'ls-remote', git_url, '--verify',
+                          'refs/heads/master'])