tools/sync-webkit-git.py

   1 #!/usr/bin/env python
   2 # Copyright (c) 2011 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 """Update third_party/WebKit using git.
   7
   8 Under the assumption third_party/WebKit is a clone of git.webkit.org,
   9 we can use git commands to make it match the version requested by DEPS.
  10
  11 See http://code.google.com/p/chromium/wiki/UsingWebKitGit for details on
  12 how to use this.
  13 """
  14
  15 import logging
  16 import optparse
  17 import os
  18 import re
  19 import subprocess
  20 import sys
  21 import urllib
  22
  23
  24 def RunGit(command):
  25   """Run a git subcommand, returning its output."""
  26   # On Windows, use shell=True to get PATH interpretation.
  27   command = ['git'] + command
  28   logging.info(' '.join(command))
  29   shell = (os.name == 'nt')
  30   proc = subprocess.Popen(command, shell=shell, stdout=subprocess.PIPE)
  31   out = proc.communicate()[0].strip()
  32   logging.info('Returned "%s"' % out)
  33   return out
  34
  35
  36 def GetOverrideShortBranchName():
  37   """Returns the user-configured override branch name, if any."""
  38   override_config_name = 'chromium.sync-branch'
  39   return RunGit(['config', '--get', override_config_name])
  40
  41
  42 def GetGClientBranchName():
  43   """Returns the name of the magic branch that lets us know that DEPS is
  44   managing the update cycle."""
  45   # Is there an override branch specified?
  46   override_branch_name = GetOverrideShortBranchName()
  47   if not override_branch_name:
  48     return 'refs/heads/gclient' # No override, so return the default branch.
  49
  50   # Verify that the branch from config exists.
  51   ref_branch = 'refs/heads/' + override_branch_name
  52   current_head = RunGit(['show-ref', '--hash', ref_branch])
  53   if current_head:
  54     return ref_branch
  55
  56   # Inform the user about the problem and how to fix it.
  57   print ("The specified override branch ('%s') doesn't appear to exist." %
  58          override_branch_name)
  59   print "Please fix your git config value '%s'." % overide_config_name
  60   sys.exit(1)
  61
  62
  63 def GetWebKitRev():
  64   """Extract the 'webkit_revision' variable out of DEPS."""
  65   locals = {'Var': lambda _: locals["vars"][_],
  66             'From': lambda *args: None}
  67   execfile('DEPS', {}, locals)
  68   return locals['vars']['webkit_revision']
  69
  70
  71 def GetWebKitRevFromTarball(version):
  72   """Extract the 'webkit_revision' variable out of tarball DEPS."""
  73   deps_url = "http://src.chromium.org/svn/releases/" + version + "/DEPS"
  74   f = urllib.urlopen(deps_url)
  75   s = f.read()
  76   m = re.search('(?<=/Source@)\w+', s)
  77   return m.group(0)
  78
  79
  80 def FindSVNRev(branch_name, target_rev):
  81   """Map an SVN revision to a git hash.
  82   Like 'git svn find-rev' but without the git-svn bits."""
  83
  84   # We iterate through the commit log looking for "git-svn-id" lines,
  85   # which contain the SVN revision of that commit.  We can stop once
  86   # we've found our target (or hit a revision number lower than what
  87   # we're looking for, indicating not found).
  88
  89   target_rev = int(target_rev)
  90
  91   # regexp matching the "commit" line from the log.
  92   commit_re = re.compile(r'^commit ([a-f\d]{40})$')
  93   # regexp matching the git-svn line from the log.
  94   git_svn_re = re.compile(r'^\s+git-svn-id: [^@]+@(\d+) ')
  95   if not branch_name:
  96     branch_name = 'origin/master'
  97   cmd = ['git', 'log', '--no-color', '--first-parent', '--pretty=medium',
  98          branch_name]
  99   logging.info(' '.join(cmd))
 100   log = subprocess.Popen(cmd, shell=(os.name == 'nt'), stdout=subprocess.PIPE)
 101   # Track whether we saw a revision *later* than the one we're seeking.
 102   saw_later = False
 103   for line in log.stdout:
 104     match = commit_re.match(line)
 105     if match:
 106       commit = match.group(1)
 107       continue
 108     match = git_svn_re.match(line)
 109     if match:
 110       rev = int(match.group(1))
 111       if rev <= target_rev:
 112         log.stdout.close()  # Break pipe.
 113         if rev < target_rev:
 114           if not saw_later:
 115             return None  # Can't be sure whether this rev is ok.
 116           print ("WARNING: r%d not found, so using next nearest earlier r%d" %
 117                  (target_rev, rev))
 118         return commit
 119       else:
 120         saw_later = True
 121
 122   print "Error: reached end of log without finding commit info."
 123   print "Something has likely gone horribly wrong."
 124   return None
 125
 126
 127 def GetRemote():
 128   branch = GetOverrideShortBranchName()
 129   if not branch:
 130     branch = 'gclient'
 131
 132   remote = RunGit(['config', '--get', 'branch.' + branch + '.remote'])
 133   if remote:
 134     return remote
 135   return 'origin'
 136
 137
 138 def UpdateGClientBranch(branch_name, webkit_rev, magic_gclient_branch):
 139   """Update the magic gclient branch to point at |webkit_rev|.
 140
 141   Returns: true if the branch didn't need changes."""
 142   target = FindSVNRev(branch_name, webkit_rev)
 143   if not target:
 144     print "r%s not available; fetching." % webkit_rev
 145     subprocess.check_call(['git', 'fetch', GetRemote()],
 146                           shell=(os.name == 'nt'))
 147     target = FindSVNRev(branch_name, webkit_rev)
 148   if not target:
 149     print "ERROR: Couldn't map r%s to a git revision." % webkit_rev
 150     sys.exit(1)
 151
 152   current = RunGit(['show-ref', '--hash', magic_gclient_branch])
 153   if current == target:
 154     return False  # No change necessary.
 155
 156   subprocess.check_call(['git', 'update-ref', '-m', 'gclient sync',
 157                          magic_gclient_branch, target],
 158                          shell=(os.name == 'nt'))
 159   return True
 160
 161
 162 def UpdateCurrentCheckoutIfAppropriate(magic_gclient_branch):
 163   """Reset the current gclient branch if that's what we have checked out."""
 164   branch = RunGit(['symbolic-ref', '-q', 'HEAD'])
 165   if branch != magic_gclient_branch:
 166     print "We have now updated the 'gclient' branch, but third_party/WebKit"
 167     print "has some other branch ('%s') checked out." % branch
 168     print "Run 'git checkout gclient' under third_party/WebKit if you want"
 169     print "to switch it to the version requested by DEPS."
 170     return 1
 171
 172   if subprocess.call(['git', 'diff-index', '--exit-code', '--shortstat',
 173                       'HEAD'], shell=(os.name == 'nt')):
 174     print "Resetting tree state to new revision."
 175     subprocess.check_call(['git', 'reset', '--hard'], shell=(os.name == 'nt'))
 176
 177
 178 def main():
 179   parser = optparse.OptionParser()
 180   parser.add_option('-v', '--verbose', action='store_true')
 181   parser.add_option('-r', '--revision', help="switch to desired revision")
 182   parser.add_option('-t', '--tarball', help="switch to desired tarball release")
 183   parser.add_option('-b', '--branch', help="branch name that gclient generate")
 184   options, args = parser.parse_args()
 185   if options.verbose:
 186     logging.basicConfig(level=logging.INFO)
 187   if not os.path.exists('third_party/WebKit/.git'):
 188     if os.path.exists('third_party/WebKit'):
 189       print "ERROR: third_party/WebKit appears to not be under git control."
 190     else:
 191       print "ERROR: third_party/WebKit could not be found."
 192       print "Did you run this script from the right directory?"
 193
 194     print "See http://code.google.com/p/chromium/wiki/UsingWebKitGit for"
 195     print "setup instructions."
 196     return 1
 197
 198   if options.revision:
 199     webkit_rev = options.revision
 200     if options.tarball:
 201       print "WARNING: --revision is given, so ignore --tarball"
 202   else:
 203     if options.tarball:
 204       webkit_rev = GetWebKitRevFromTarball(options.tarball)
 205     else:
 206       webkit_rev = GetWebKitRev()
 207
 208   print 'Desired revision: r%s.' % webkit_rev
 209   os.chdir('third_party/WebKit')
 210   magic_gclient_branch = GetGClientBranchName()
 211   changed = UpdateGClientBranch(options.branch, webkit_rev,
 212                                 magic_gclient_branch)
 213   if changed:
 214     return UpdateCurrentCheckoutIfAppropriate(magic_gclient_branch)
 215   else:
 216     print "Already on correct revision."
 217   return 0
 218
 219
 220 if __name__ == '__main__':
 221   sys.exit(main())