tools/sync-webkit-git.py

   1 #!/usr/bin/python
   2 # Copyright (c) 2010 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
  22 def RunGit(command):
  23   """Run a git subcommand, returning its output."""
  24   # On Windows, use shell=True to get PATH interpretation.
  25   command = ['git'] + command
  26   logging.info(' '.join(command))
  27   shell = (os.name == 'nt')
  28   proc = subprocess.Popen(command, shell=shell, stdout=subprocess.PIPE)
  29   out = proc.communicate()[0].strip()
  30   logging.info('Returned "%s"' % out)
  31   return out
  32
  33 def GetOverrideShortBranchName():
  34   """Returns the user-configured override branch name, if any."""
  35   override_config_name = 'chromium.sync-branch'
  36   return RunGit(['config', '--get', override_config_name])
  37
  38 def GetGClientBranchName():
  39   """Returns the name of the magic branch that lets us know that DEPS is
  40   managing the update cycle."""
  41   # Is there an override branch specified?
  42   override_branch_name = GetOverrideShortBranchName()
  43   if not override_branch_name:
  44     return 'refs/heads/gclient' # No override, so return the default branch.
  45
  46   # Verify that the branch from config exists.
  47   ref_branch = 'refs/heads/' + override_branch_name
  48   current_head = RunGit(['show-ref', '--hash', ref_branch])
  49   if current_head:
  50     return ref_branch
  51
  52   # Inform the user about the problem and how to fix it.
  53   print ("The specified override branch ('%s') doesn't appear to exist." %
  54          override_branch_name)
  55   print "Please fix your git config value '%s'." % overide_config_name
  56   sys.exit(1)
  57
  58 def GetWebKitRev():
  59   """Extract the 'webkit_revision' variable out of DEPS."""
  60   locals = {'Var': lambda _: locals["vars"][_]}
  61   execfile('DEPS', {}, locals)
  62   return locals['vars']['webkit_revision']
  63
  64 def FindSVNRev(target_rev):
  65   """Map an SVN revision to a git hash.
  66   Like 'git svn find-rev' but without the git-svn bits."""
  67
  68   # We iterate through the commit log looking for "git-svn-id" lines,
  69   # which contain the SVN revision of that commit.  We can stop once
  70   # we've found our target (or hit a revision number lower than what
  71   # we're looking for, indicating not found).
  72
  73   target_rev = int(target_rev)
  74
  75   # regexp matching the "commit" line from the log.
  76   commit_re = re.compile(r'^commit ([a-f\d]{40})$')
  77   # regexp matching the git-svn line from the log.
  78   git_svn_re = re.compile(r'^\s+git-svn-id: [^@]+@(\d+) ')
  79   cmd = ['git', 'log', '--no-color', '--first-parent', '--pretty=medium',
  80          'origin/master']
  81   logging.info(' '.join(cmd))
  82   log = subprocess.Popen(cmd, shell=(os.name == 'nt'), stdout=subprocess.PIPE)
  83   # Track whether we saw a revision *later* than the one we're seeking.
  84   saw_later = False
  85   for line in log.stdout:
  86     match = commit_re.match(line)
  87     if match:
  88       commit = match.group(1)
  89       continue
  90     match = git_svn_re.match(line)
  91     if match:
  92       rev = int(match.group(1))
  93       if rev <= target_rev:
  94         log.stdout.close()  # Break pipe.
  95         if rev < target_rev:
  96           if not saw_later:
  97             return None  # Can't be sure whether this rev is ok.
  98           print ("WARNING: r%d not found, so using next nearest earlier r%d" %
  99                  (target_rev, rev))
 100         return commit
 101       else:
 102         saw_later = True
 103
 104   print "Error: reached end of log without finding commit info."
 105   print "Something has likely gone horribly wrong."
 106   return None
 107
 108 def GetRemote():
 109   branch = GetOverrideShortBranchName()
 110   if not branch:
 111     branch = 'gclient'
 112
 113   remote = RunGit(['config', '--get', 'branch.' + branch + '.remote'])
 114   if remote:
 115     return remote
 116   return 'origin'
 117
 118 def UpdateGClientBranch(webkit_rev, magic_gclient_branch):
 119   """Update the magic gclient branch to point at |webkit_rev|.
 120
 121   Returns: true if the branch didn't need changes."""
 122   target = FindSVNRev(webkit_rev)
 123   if not target:
 124     print "r%s not available; fetching." % webkit_rev
 125     subprocess.check_call(['git', 'fetch', GetRemote()],
 126                           shell=(os.name == 'nt'))
 127     target = FindSVNRev(webkit_rev)
 128   if not target:
 129     print "ERROR: Couldn't map r%s to a git revision." % webkit_rev
 130     sys.exit(1)
 131
 132   current = RunGit(['show-ref', '--hash', magic_gclient_branch])
 133   if current == target:
 134     return False  # No change necessary.
 135
 136   subprocess.check_call(['git', 'update-ref', '-m', 'gclient sync',
 137                          magic_gclient_branch, target],
 138                          shell=(os.name == 'nt'))
 139   return True
 140
 141 def UpdateCurrentCheckoutIfAppropriate(magic_gclient_branch):
 142   """Reset the current gclient branch if that's what we have checked out."""
 143   branch = RunGit(['symbolic-ref', '-q', 'HEAD'])
 144   if branch != magic_gclient_branch:
 145     print "We have now updated the 'gclient' branch, but third_party/WebKit"
 146     print "has some other branch ('%s') checked out." % branch
 147     print "Run 'git checkout gclient' under third_party/WebKit if you want"
 148     print "to switch it to the version requested by DEPS."
 149     return 1
 150
 151   if subprocess.call(['git', 'diff-index', '--exit-code', '--shortstat',
 152                       'HEAD'], shell=(os.name == 'nt')):
 153     print "Resetting tree state to new revision."
 154     subprocess.check_call(['git', 'reset', '--hard'], shell=(os.name == 'nt'))
 155
 156 def main():
 157   parser = optparse.OptionParser()
 158   parser.add_option('-v', '--verbose', action='store_true')
 159   options, args = parser.parse_args()
 160   if options.verbose:
 161     logging.basicConfig(level=logging.INFO)
 162   if not os.path.exists('third_party/WebKit/.git'):
 163     if os.path.exists('third_party/WebKit'):
 164       print "ERROR: third_party/WebKit appears to not be under git control."
 165     else:
 166       print "ERROR: third_party/WebKit could not be found."
 167       print "Did you run this script from the right directory?"
 168
 169     print "See http://code.google.com/p/chromium/wiki/UsingWebKitGit for"
 170     print "setup instructions."
 171     return 1
 172
 173   webkit_rev = GetWebKitRev()
 174   print 'Desired revision: r%s.' % webkit_rev
 175   os.chdir('third_party/WebKit')
 176   magic_gclient_branch = GetGClientBranchName()
 177   changed = UpdateGClientBranch(webkit_rev, magic_gclient_branch)
 178   if changed:
 179     return UpdateCurrentCheckoutIfAppropriate(magic_gclient_branch)
 180   else:
 181     print "Already on correct revision."
 182   return 0
 183
 184 if __name__ == '__main__':
 185   sys.exit(main())