michael@0: #!/usr/bin/env python
michael@0: # Copyright (c) 2012 The Chromium Authors. All rights reserved.
michael@0: # Use of this source code is governed by a BSD-style license that can be
michael@0: # found in the LICENSE file.
michael@0: 
michael@0: """
michael@0: lastchange.py -- Chromium revision fetching utility.
michael@0: """
michael@0: 
michael@0: import re
michael@0: import optparse
michael@0: import os
michael@0: import subprocess
michael@0: import sys
michael@0: 
michael@0: _GIT_SVN_ID_REGEX = re.compile(r'.*git-svn-id:\s*([^@]*)@([0-9]+)', re.DOTALL)
michael@0: 
michael@0: class VersionInfo(object):
michael@0:   def __init__(self, url, revision):
michael@0:     self.url = url
michael@0:     self.revision = revision
michael@0: 
michael@0: 
michael@0: def FetchSVNRevision(directory, svn_url_regex):
michael@0:   """
michael@0:   Fetch the Subversion branch and revision for a given directory.
michael@0: 
michael@0:   Errors are swallowed.
michael@0: 
michael@0:   Returns:
michael@0:     A VersionInfo object or None on error.
michael@0:   """
michael@0:   try:
michael@0:     proc = subprocess.Popen(['svn', 'info'],
michael@0:                             stdout=subprocess.PIPE,
michael@0:                             stderr=subprocess.PIPE,
michael@0:                             cwd=directory,
michael@0:                             shell=(sys.platform=='win32'))
michael@0:   except OSError:
michael@0:     # command is apparently either not installed or not executable.
michael@0:     return None
michael@0:   if not proc:
michael@0:     return None
michael@0: 
michael@0:   attrs = {}
michael@0:   for line in proc.stdout:
michael@0:     line = line.strip()
michael@0:     if not line:
michael@0:       continue
michael@0:     key, val = line.split(': ', 1)
michael@0:     attrs[key] = val
michael@0: 
michael@0:   try:
michael@0:     match = svn_url_regex.search(attrs['URL'])
michael@0:     if match:
michael@0:       url = match.group(2)
michael@0:     else:
michael@0:       url = ''
michael@0:     revision = attrs['Revision']
michael@0:   except KeyError:
michael@0:     return None
michael@0: 
michael@0:   return VersionInfo(url, revision)
michael@0: 
michael@0: 
michael@0: def RunGitCommand(directory, command):
michael@0:   """
michael@0:   Launches git subcommand.
michael@0: 
michael@0:   Errors are swallowed.
michael@0: 
michael@0:   Returns:
michael@0:     A process object or None.
michael@0:   """
michael@0:   command = ['git'] + command
michael@0:   # Force shell usage under cygwin. This is a workaround for
michael@0:   # mysterious loss of cwd while invoking cygwin's git.
michael@0:   # We can't just pass shell=True to Popen, as under win32 this will
michael@0:   # cause CMD to be used, while we explicitly want a cygwin shell.
michael@0:   if sys.platform == 'cygwin':
michael@0:     command = ['sh', '-c', ' '.join(command)]
michael@0:   try:
michael@0:     proc = subprocess.Popen(command,
michael@0:                             stdout=subprocess.PIPE,
michael@0:                             stderr=subprocess.PIPE,
michael@0:                             cwd=directory,
michael@0:                             shell=(sys.platform=='win32'))
michael@0:     return proc
michael@0:   except OSError:
michael@0:     return None
michael@0: 
michael@0: 
michael@0: def FetchGitRevision(directory):
michael@0:   """
michael@0:   Fetch the Git hash for a given directory.
michael@0: 
michael@0:   Errors are swallowed.
michael@0: 
michael@0:   Returns:
michael@0:     A VersionInfo object or None on error.
michael@0:   """
michael@0:   proc = RunGitCommand(directory, ['rev-parse', 'HEAD'])
michael@0:   if proc:
michael@0:     output = proc.communicate()[0].strip()
michael@0:     if proc.returncode == 0 and output:
michael@0:       return VersionInfo('git', output[:7])
michael@0:   return None
michael@0: 
michael@0: 
michael@0: def FetchGitSVNURLAndRevision(directory, svn_url_regex):
michael@0:   """
michael@0:   Fetch the Subversion URL and revision through Git.
michael@0: 
michael@0:   Errors are swallowed.
michael@0: 
michael@0:   Returns:
michael@0:     A tuple containing the Subversion URL and revision.
michael@0:   """
michael@0:   proc = RunGitCommand(directory, ['log', '-1',
michael@0:                                    '--grep=git-svn-id', '--format=%b'])
michael@0:   if proc:
michael@0:     output = proc.communicate()[0].strip()
michael@0:     if proc.returncode == 0 and output:
michael@0:       # Extract the latest SVN revision and the SVN URL.
michael@0:       # The target line is the last "git-svn-id: ..." line like this:
michael@0:       # git-svn-id: svn://svn.chromium.org/chrome/trunk/src@85528 0039d316....
michael@0:       match = _GIT_SVN_ID_REGEX.search(output)
michael@0:       if match:
michael@0:         revision = match.group(2)
michael@0:         url_match = svn_url_regex.search(match.group(1))
michael@0:         if url_match:
michael@0:           url = url_match.group(2)
michael@0:         else:
michael@0:           url = ''
michael@0:         return url, revision
michael@0:   return None, None
michael@0: 
michael@0: 
michael@0: def FetchGitSVNRevision(directory, svn_url_regex):
michael@0:   """
michael@0:   Fetch the Git-SVN identifier for the local tree.
michael@0: 
michael@0:   Errors are swallowed.
michael@0:   """
michael@0:   url, revision = FetchGitSVNURLAndRevision(directory, svn_url_regex)
michael@0:   if url and revision:
michael@0:     return VersionInfo(url, revision)
michael@0:   return None
michael@0: 
michael@0: 
michael@0: def FetchVersionInfo(default_lastchange, directory=None,
michael@0:                      directory_regex_prior_to_src_url='chrome|svn'):
michael@0:   """
michael@0:   Returns the last change (in the form of a branch, revision tuple),
michael@0:   from some appropriate revision control system.
michael@0:   """
michael@0:   svn_url_regex = re.compile(
michael@0:       r'.*/(' + directory_regex_prior_to_src_url + r')(/.*)')
michael@0: 
michael@0:   version_info = (FetchSVNRevision(directory, svn_url_regex) or
michael@0:                   FetchGitSVNRevision(directory, svn_url_regex) or
michael@0:                   FetchGitRevision(directory))
michael@0:   if not version_info:
michael@0:     if default_lastchange and os.path.exists(default_lastchange):
michael@0:       revision = open(default_lastchange, 'r').read().strip()
michael@0:       version_info = VersionInfo(None, revision)
michael@0:     else:
michael@0:       version_info = VersionInfo(None, None)
michael@0:   return version_info
michael@0: 
michael@0: 
michael@0: def WriteIfChanged(file_name, contents):
michael@0:   """
michael@0:   Writes the specified contents to the specified file_name
michael@0:   iff the contents are different than the current contents.
michael@0:   """
michael@0:   try:
michael@0:     old_contents = open(file_name, 'r').read()
michael@0:   except EnvironmentError:
michael@0:     pass
michael@0:   else:
michael@0:     if contents == old_contents:
michael@0:       return
michael@0:     os.unlink(file_name)
michael@0:   open(file_name, 'w').write(contents)
michael@0: 
michael@0: 
michael@0: def main(argv=None):
michael@0:   if argv is None:
michael@0:     argv = sys.argv
michael@0: 
michael@0:   parser = optparse.OptionParser(usage="lastchange.py [options]")
michael@0:   parser.add_option("-d", "--default-lastchange", metavar="FILE",
michael@0:                     help="default last change input FILE")
michael@0:   parser.add_option("-o", "--output", metavar="FILE",
michael@0:                     help="write last change to FILE")
michael@0:   parser.add_option("--revision-only", action='store_true',
michael@0:                     help="just print the SVN revision number")
michael@0:   opts, args = parser.parse_args(argv[1:])
michael@0: 
michael@0:   out_file = opts.output
michael@0: 
michael@0:   while len(args) and out_file is None:
michael@0:     if out_file is None:
michael@0:       out_file = args.pop(0)
michael@0:   if args:
michael@0:     sys.stderr.write('Unexpected arguments: %r\n\n' % args)
michael@0:     parser.print_help()
michael@0:     sys.exit(2)
michael@0: 
michael@0:   version_info = FetchVersionInfo(opts.default_lastchange,
michael@0:       os.path.dirname(sys.argv[0]))
michael@0: 
michael@0:   if version_info.revision == None:
michael@0:     version_info.revision = '0'
michael@0: 
michael@0:   if opts.revision_only:
michael@0:     print version_info.revision
michael@0:   else:
michael@0:     contents = "LASTCHANGE=%s\n" % version_info.revision
michael@0:     if out_file:
michael@0:       WriteIfChanged(out_file, contents)
michael@0:     else:
michael@0:       sys.stdout.write(contents)
michael@0: 
michael@0:   return 0
michael@0: 
michael@0: 
michael@0: if __name__ == '__main__':
michael@0:   sys.exit(main())