1 # Copyright 2014 The Chromium Authors. All rights reserved.
2 # Use of this source code is governed by a BSD-style license that can be
3 # found in the LICENSE file.
5 """Writes the most recent "Cr-Commit-Position" value on the master branch
8 Usage: last_commit_position.py <dir> <outfile> <headerguard>
11 Some directory inside the repo to check. This will be used as the current
12 directory when running git. It's best to pass the repo toplevel directory.
15 C header file to write.
18 String to use as the header guard for the written file.
26 def RunGitCommand(directory, command):
28 Launches git subcommand.
33 A process object or None.
35 command = ['git'] + command
36 # Force shell usage under cygwin. This is a workaround for
37 # mysterious loss of cwd while invoking cygwin's git.
38 # We can't just pass shell=True to Popen, as under win32 this will
39 # cause CMD to be used, while we explicitly want a cygwin shell.
40 if sys.platform == 'cygwin':
41 command = ['sh', '-c', ' '.join(command)]
43 proc = subprocess.Popen(command,
44 stdout=subprocess.PIPE,
45 stderr=subprocess.PIPE,
47 shell=(sys.platform=='win32'))
53 def FetchCommitPosition(directory):
54 regex = re.compile(r'\s*Cr-Commit-Position: refs/heads/master@\{#(\d+)\}\s*')
56 # Search this far backward in the git log. The commit position should be
57 # close to the top. We allow some slop for long commit messages, and maybe
58 # there were some local commits after the last "official" one. Having this
59 # max prevents us from searching all history in the case of an error.
62 proc = RunGitCommand(directory, ['log'])
63 for i in range(max_lines):
64 line = proc.stdout.readline()
68 match = regex.match(line)
75 def WriteHeader(header_file, header_guard, value):
76 with open(header_file, 'w') as f:
77 f.write('''/* Generated by last_commit_position.py. */
82 #define LAST_COMMIT_POSITION "%(value)s"
85 ''' % {'guard': header_guard, 'value': value})
88 if len(sys.argv) != 4:
89 print "Wrong number of arguments"
92 git_directory = sys.argv[1]
93 output_file = sys.argv[2]
94 header_guard = sys.argv[3]
96 value = FetchCommitPosition(git_directory)
98 print "Could not get last commit position."
101 WriteHeader(output_file, header_guard, value)