tools/sync-webkit-git.py

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