1#!/usr/bin/env python
2# Copyright (c) 2012 The Chromium Authors. All rights reserved.
3# Use of this source code is governed by a BSD-style license that can be
4# found in the LICENSE file.
5
6"""
7lastchange.py -- Chromium revision fetching utility.
8"""
9
10import re
11import optparse
12import os
13import subprocess
14import sys
15
16_GIT_SVN_ID_REGEX = re.compile(r'.*git-svn-id:\s*([^@]*)@([0-9]+)', re.DOTALL)
17
18class VersionInfo(object):
19  def __init__(self, url, revision):
20    self.url = url
21    self.revision = revision
22
23
24def FetchSVNRevision(directory, svn_url_regex):
25  """
26  Fetch the Subversion branch and revision for a given directory.
27
28  Errors are swallowed.
29
30  Returns:
31    A VersionInfo object or None on error.
32  """
33  try:
34    proc = subprocess.Popen(['svn', 'info'],
35                            stdout=subprocess.PIPE,
36                            stderr=subprocess.PIPE,
37                            cwd=directory,
38                            shell=(sys.platform=='win32'))
39  except OSError:
40    # command is apparently either not installed or not executable.
41    return None
42  if not proc:
43    return None
44
45  attrs = {}
46  for line in proc.stdout:
47    line = line.strip()
48    if not line:
49      continue
50    key, val = line.split(': ', 1)
51    attrs[key] = val
52
53  try:
54    match = svn_url_regex.search(attrs['URL'])
55    if match:
56      url = match.group(2)
57    else:
58      url = ''
59    revision = attrs['Revision']
60  except KeyError:
61    return None
62
63  return VersionInfo(url, revision)
64
65
66def RunGitCommand(directory, command):
67  """
68  Launches git subcommand.
69
70  Errors are swallowed.
71
72  Returns:
73    A process object or None.
74  """
75  command = ['git'] + command
76  # Force shell usage under cygwin. This is a workaround for
77  # mysterious loss of cwd while invoking cygwin's git.
78  # We can't just pass shell=True to Popen, as under win32 this will
79  # cause CMD to be used, while we explicitly want a cygwin shell.
80  if sys.platform == 'cygwin':
81    command = ['sh', '-c', ' '.join(command)]
82  try:
83    proc = subprocess.Popen(command,
84                            stdout=subprocess.PIPE,
85                            stderr=subprocess.PIPE,
86                            cwd=directory,
87                            shell=(sys.platform=='win32'))
88    return proc
89  except OSError:
90    return None
91
92
93def FetchGitRevision(directory):
94  """
95  Fetch the Git hash for a given directory.
96
97  Errors are swallowed.
98
99  Returns:
100    A VersionInfo object or None on error.
101  """
102  proc = RunGitCommand(directory, ['rev-parse', 'HEAD'])
103  if proc:
104    output = proc.communicate()[0].strip()
105    if proc.returncode == 0 and output:
106      return VersionInfo('git', output[:7])
107  return None
108
109
110def FetchGitSVNURLAndRevision(directory, svn_url_regex):
111  """
112  Fetch the Subversion URL and revision through Git.
113
114  Errors are swallowed.
115
116  Returns:
117    A tuple containing the Subversion URL and revision.
118  """
119  proc = RunGitCommand(directory, ['log', '-1',
120                                   '--grep=git-svn-id', '--format=%b'])
121  if proc:
122    output = proc.communicate()[0].strip()
123    if proc.returncode == 0 and output:
124      # Extract the latest SVN revision and the SVN URL.
125      # The target line is the last "git-svn-id: ..." line like this:
126      # git-svn-id: svn://svn.chromium.org/chrome/trunk/src@85528 0039d316....
127      match = _GIT_SVN_ID_REGEX.search(output)
128      if match:
129        revision = match.group(2)
130        url_match = svn_url_regex.search(match.group(1))
131        if url_match:
132          url = url_match.group(2)
133        else:
134          url = ''
135        return url, revision
136  return None, None
137
138
139def FetchGitSVNRevision(directory, svn_url_regex):
140  """
141  Fetch the Git-SVN identifier for the local tree.
142
143  Errors are swallowed.
144  """
145  url, revision = FetchGitSVNURLAndRevision(directory, svn_url_regex)
146  if url and revision:
147    return VersionInfo(url, revision)
148  return None
149
150
151def FetchVersionInfo(default_lastchange, directory=None,
152                     directory_regex_prior_to_src_url='chrome|blink|svn'):
153  """
154  Returns the last change (in the form of a branch, revision tuple),
155  from some appropriate revision control system.
156  """
157  svn_url_regex = re.compile(
158      r'.*/(' + directory_regex_prior_to_src_url + r')(/.*)')
159
160  version_info = (FetchSVNRevision(directory, svn_url_regex) or
161                  FetchGitSVNRevision(directory, svn_url_regex) or
162                  FetchGitRevision(directory))
163  if not version_info:
164    if default_lastchange and os.path.exists(default_lastchange):
165      revision = open(default_lastchange, 'r').read().strip()
166      version_info = VersionInfo(None, revision)
167    else:
168      version_info = VersionInfo(None, None)
169  return version_info
170
171
172def WriteIfChanged(file_name, contents):
173  """
174  Writes the specified contents to the specified file_name
175  iff the contents are different than the current contents.
176  """
177  try:
178    old_contents = open(file_name, 'r').read()
179  except EnvironmentError:
180    pass
181  else:
182    if contents == old_contents:
183      return
184    os.unlink(file_name)
185  open(file_name, 'w').write(contents)
186
187
188def main(argv=None):
189  if argv is None:
190    argv = sys.argv
191
192  parser = optparse.OptionParser(usage="lastchange.py [options]")
193  parser.add_option("-d", "--default-lastchange", metavar="FILE",
194                    help="default last change input FILE")
195  parser.add_option("-o", "--output", metavar="FILE",
196                    help="write last change to FILE")
197  parser.add_option("--revision-only", action='store_true',
198                    help="just print the SVN revision number")
199  parser.add_option("-s", "--source-dir", metavar="DIR",
200                    help="use repository in the given directory")
201  opts, args = parser.parse_args(argv[1:])
202
203  out_file = opts.output
204
205  while len(args) and out_file is None:
206    if out_file is None:
207      out_file = args.pop(0)
208  if args:
209    sys.stderr.write('Unexpected arguments: %r\n\n' % args)
210    parser.print_help()
211    sys.exit(2)
212
213  if opts.source_dir:
214    src_dir = opts.source_dir
215  else:
216    src_dir = os.path.dirname(os.path.abspath(__file__))
217
218  version_info = FetchVersionInfo(opts.default_lastchange, src_dir)
219
220  if version_info.revision == None:
221    version_info.revision = '0'
222
223  if opts.revision_only:
224    print version_info.revision
225  else:
226    contents = "LASTCHANGE=%s\n" % version_info.revision
227    if out_file:
228      WriteIfChanged(out_file, contents)
229    else:
230      sys.stdout.write(contents)
231
232  return 0
233
234
235if __name__ == '__main__':
236  sys.exit(main())
237