build/util/lastchange.py

   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 """
   7 lastchange.py -- Chromium revision fetching utility.
   8 """
   9
  10 import re
  11 import optparse
  12 import os
  13 import subprocess
  14 import sys
  15
  16 _GIT_SVN_ID_REGEX = re.compile(r'.*git-svn-id:\s*([^@]*)@([0-9]+)', re.DOTALL)
  17
  18 class VersionInfo(object):
  19   def __init__(self, url, revision):
  20     self.url = url
  21     self.revision = revision
  22
  23
  24 def 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
  66 def 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
  93 def 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
 110 def 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
 139 def 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
 151 def FetchVersionInfo(default_lastchange, directory=None,
 152                      directory_regex_prior_to_src_url='chrome|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
 172 def 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
 188 def 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
 235 if __name__ == '__main__':
 236   sys.exit(main())