git_cl/git_cl.py

#!/usr/bin/python
# git-cl -- a git-command for integrating reviews on Rietveld
# Copyright (C) 2008 Evan Martin <martine@danga.com>

import errno
import logging
import optparse
import os
import re
import subprocess
import sys
import tempfile
import textwrap
import upload
import urllib2

try:
  import readline
except ImportError:
  pass

try:
  # Add the parent directory in case it's a depot_tools checkout.
  depot_tools_path = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
  sys.path.append(depot_tools_path)
  import breakpad
except ImportError:
  pass

DEFAULT_SERVER = 'http://codereview.appspot.com'
PREDCOMMIT_HOOK = '.git/hooks/pre-cl-dcommit'
POSTUPSTREAM_HOOK_PATTERN = '.git/hooks/post-cl-%s'
PREUPLOAD_HOOK = '.git/hooks/pre-cl-upload'
DESCRIPTION_BACKUP_FILE = '~/.git_cl_description_backup'

def DieWithError(message):
  print >>sys.stderr, message
  sys.exit(1)


def Popen(cmd, **kwargs):
  """Wrapper for subprocess.Popen() that logs and watch for cygwin issues"""
  logging.info('Popen: ' + ' '.join(cmd))
  try:
    return subprocess.Popen(cmd, **kwargs)
  except OSError, e:
    if e.errno == errno.EAGAIN and sys.platform == 'cygwin':
      DieWithError(
          'Visit '
          'http://code.google.com/p/chromium/wiki/CygwinDllRemappingFailure to '
          'learn how to fix this error; you need to rebase your cygwin dlls')
    raise


def RunCommand(cmd, error_ok=False, error_message=None,
               redirect_stdout=True, swallow_stderr=False):
  if redirect_stdout:
    stdout = subprocess.PIPE
  else:
    stdout = None
  if swallow_stderr:
    stderr = subprocess.PIPE
  else:
    stderr = None
  proc = Popen(cmd, stdout=stdout, stderr=stderr)
  output = proc.communicate()[0]
  if not error_ok and proc.returncode != 0:
    DieWithError('Command "%s" failed.\n' % (' '.join(cmd)) +
                 (error_message or output or ''))
  return output


def RunGit(args, **kwargs):
  cmd = ['git'] + args
  return RunCommand(cmd, **kwargs)


def RunGitWithCode(args):
  proc = Popen(['git'] + args, stdout=subprocess.PIPE)
  output = proc.communicate()[0]
  return proc.returncode, output


def usage(more):
  def hook(fn):
    fn.usage_more = more
    return fn
  return hook


def FixUrl(server):
  """Fix a server url to defaults protocol to http:// if none is specified."""
  if not server:
    return server
  if not re.match(r'[a-z]+\://.*', server):
    return 'http://' + server
  return server


class Settings(object):
  def __init__(self):
    self.default_server = None
    self.cc = None
    self.root = None
    self.is_git_svn = None
    self.svn_branch = None
    self.tree_status_url = None
    self.viewvc_url = None
    self.updated = False

  def LazyUpdateIfNeeded(self):
    """Updates the settings from a codereview.settings file, if available."""
    if not self.updated:
      cr_settings_file = FindCodereviewSettingsFile()
      if cr_settings_file:
        LoadCodereviewSettingsFromFile(cr_settings_file)
      self.updated = True

  def GetDefaultServerUrl(self, error_ok=False):
    if not self.default_server:
      self.LazyUpdateIfNeeded()
      self.default_server = FixUrl(self._GetConfig('rietveld.server',
                                                   error_ok=True))
      if error_ok:
        return self.default_server
      if not self.default_server:
        error_message = ('Could not find settings file. You must configure '
                         'your review setup by running "git cl config".')
        self.default_server = FixUrl(self._GetConfig(
            'rietveld.server', error_message=error_message))
    return self.default_server

  def GetCCList(self):
    """Return the users cc'd on this CL.

    Return is a string suitable for passing to gcl with the --cc flag.
    """
    if self.cc is None:
      self.cc = self._GetConfig('rietveld.cc', error_ok=True)
      more_cc = self._GetConfig('rietveld.extracc', error_ok=True)
      if more_cc is not None:
        self.cc += ',' + more_cc
    return self.cc

  def GetRoot(self):
    if not self.root:
      self.root = os.path.abspath(RunGit(['rev-parse', '--show-cdup']).strip())
    return self.root

  def GetIsGitSvn(self):
    """Return true if this repo looks like it's using git-svn."""
    if self.is_git_svn is None:
      # If you have any "svn-remote.*" config keys, we think you're using svn.
      self.is_git_svn = RunGitWithCode(
          ['config', '--get-regexp', r'^svn-remote\.'])[0] == 0
    return self.is_git_svn

  def GetSVNBranch(self):
    if self.svn_branch is None:
      if not self.GetIsGitSvn():
        DieWithError('Repo doesn\'t appear to be a git-svn repo.')

      # Try to figure out which remote branch we're based on.
      # Strategy:
      # 1) find all git-svn branches and note their svn URLs.
      # 2) iterate through our branch history and match up the URLs.

      # regexp matching the git-svn line that contains the URL.
      git_svn_re = re.compile(r'^\s*git-svn-id: (\S+)@', re.MULTILINE)

      # Get the refname and svn url for all refs/remotes/*.
      remotes = RunGit(['for-each-ref', '--format=%(refname)',
                        'refs/remotes']).splitlines()
      svn_refs = {}
      for ref in remotes:
        match = git_svn_re.search(RunGit(['cat-file', '-p', ref]))
        # Prefer origin/HEAD over all others.
        if match and (match.group(1) not in svn_refs or
                      ref == "refs/remotes/origin/HEAD"):
          svn_refs[match.group(1)] = ref

      if len(svn_refs) == 1:
        # Only one svn branch exists -- seems like a good candidate.
        self.svn_branch = svn_refs.values()[0]
      elif len(svn_refs) > 1:
        # We have more than one remote branch available.  We don't
        # want to go through all of history, so read a line from the
        # pipe at a time.
        # The -100 is an arbitrary limit so we don't search forever.
        cmd = ['git', 'log', '-100', '--pretty=medium']
        proc = Popen(cmd, stdout=subprocess.PIPE)
        for line in proc.stdout:
          match = git_svn_re.match(line)
          if match:
            url = match.group(1)
            if url in svn_refs:
              self.svn_branch = svn_refs[url]
              proc.stdout.close()  # Cut pipe.
              break

      if not self.svn_branch:
        DieWithError('Can\'t guess svn branch -- try specifying it on the '
            'command line')

    return self.svn_branch

  def GetTreeStatusUrl(self, error_ok=False):
    if not self.tree_status_url:
      error_message = ('You must configure your tree status URL by running '
                       '"git cl config".')
      self.tree_status_url = self._GetConfig('rietveld.tree-status-url',
                                             error_ok=error_ok,
                                             error_message=error_message)
    return self.tree_status_url

  def GetViewVCUrl(self):
    if not self.viewvc_url:
      self.viewvc_url = self._GetConfig('rietveld.viewvc-url', error_ok=True)
    return self.viewvc_url

  def _GetConfig(self, param, **kwargs):
    self.LazyUpdateIfNeeded()
    return RunGit(['config', param], **kwargs).strip()


settings = Settings()


did_migrate_check = False
def CheckForMigration():
  """Migrate from the old issue format, if found.

  We used to store the branch<->issue mapping in a file in .git, but it's
  better to store it in the .git/config, since deleting a branch deletes that
  branch's entry there.
  """

  # Don't run more than once.
  global did_migrate_check
  if did_migrate_check:
    return

  gitdir = RunGit(['rev-parse', '--git-dir']).strip()
  storepath = os.path.join(gitdir, 'cl-mapping')
  if os.path.exists(storepath):
    print "old-style git-cl mapping file (%s) found; migrating." % storepath
    store = open(storepath, 'r')
    for line in store:
      branch, issue = line.strip().split()
      RunGit(['config', 'branch.%s.rietveldissue' % ShortBranchName(branch),
              issue])
    store.close()
    os.remove(storepath)
  did_migrate_check = True


def ShortBranchName(branch):
  """Convert a name like 'refs/heads/foo' to just 'foo'."""
  return branch.replace('refs/heads/', '')


class Changelist(object):
  def __init__(self, branchref=None):
    # Poke settings so we get the "configure your server" message if necessary.
    settings.GetDefaultServerUrl()
    self.branchref = branchref
    if self.branchref:
      self.branch = ShortBranchName(self.branchref)
    else:
      self.branch = None
    self.rietveld_server = None
    self.upstream_branch = None
    self.has_issue = False
    self.issue = None
    self.has_description = False
    self.description = None
    self.has_patchset = False
    self.patchset = None

  def GetBranch(self):
    """Returns the short branch name, e.g. 'master'."""
    if not self.branch:
      self.branchref = RunGit(['symbolic-ref', 'HEAD']).strip()
      self.branch = ShortBranchName(self.branchref)
    return self.branch

  def GetBranchRef(self):
    """Returns the full branch name, e.g. 'refs/heads/master'."""
    self.GetBranch()  # Poke the lazy loader.
    return self.branchref

  def FetchUpstreamTuple(self):
    """Returns a tuple containg remote and remote ref,
       e.g. 'origin', 'refs/heads/master'
    """
    remote = '.'
    branch = self.GetBranch()
    upstream_branch = RunGit(['config', 'branch.%s.merge' % branch],
                             error_ok=True).strip()
    if upstream_branch:
      remote = RunGit(['config', 'branch.%s.remote' % branch]).strip()
    else:
      # Fall back on trying a git-svn upstream branch.
      if settings.GetIsGitSvn():
        upstream_branch = settings.GetSVNBranch()
      else:
        # Else, try to guess the origin remote.
        remote_branches = RunGit(['branch', '-r']).split()
        if 'origin/master' in remote_branches:
          # Fall back on origin/master if it exits.
          remote = 'origin'
          upstream_branch = 'refs/heads/master'
        elif 'origin/trunk' in remote_branches:
          # Fall back on origin/trunk if it exists. Generally a shared
          # git-svn clone
          remote = 'origin'
          upstream_branch = 'refs/heads/trunk'
        else:
          DieWithError("""Unable to determine default branch to diff against.
Either pass complete "git diff"-style arguments, like
  git cl upload origin/master
or verify this branch is set up to track another (via the --track argument to
"git checkout -b ...").""")

    return remote, upstream_branch

  def GetUpstreamBranch(self):
    if self.upstream_branch is None:
      remote, upstream_branch = self.FetchUpstreamTuple()
      if remote is not '.':
        upstream_branch = upstream_branch.replace('heads', 'remotes/' + remote)
      self.upstream_branch = upstream_branch
    return self.upstream_branch

  def GetRemoteUrl(self):
    """Return the configured remote URL, e.g. 'git://example.org/foo.git/'.

    Returns None if there is no remote.
    """
    remote = self.FetchUpstreamTuple()[0]
    if remote == '.':
      return None
    return RunGit(['config', 'remote.%s.url' % remote], error_ok=True).strip()

  def GetIssue(self):
    if not self.has_issue:
      CheckForMigration()
      issue = RunGit(['config', self._IssueSetting()], error_ok=True).strip()
      if issue:
        self.issue = issue
        self.rietveld_server = FixUrl(RunGit(
            ['config', self._RietveldServer()], error_ok=True).strip())
      else:
        self.issue = None
      if not self.rietveld_server:
        self.rietveld_server = settings.GetDefaultServerUrl()
      self.has_issue = True
    return self.issue

  def GetRietveldServer(self):
    self.GetIssue()
    return self.rietveld_server

  def GetIssueURL(self):
    """Get the URL for a particular issue."""
    return '%s/%s' % (self.GetRietveldServer(), self.GetIssue())

  def GetDescription(self, pretty=False):
    if not self.has_description:
      if self.GetIssue():
        path = '/' + self.GetIssue() + '/description'
        rpc_server = self._RpcServer()
        self.description = rpc_server.Send(path).strip()
      self.has_description = True
    if pretty:
      wrapper = textwrap.TextWrapper()
      wrapper.initial_indent = wrapper.subsequent_indent = '  '
      return wrapper.fill(self.description)
    return self.description

  def GetPatchset(self):
    if not self.has_patchset:
      patchset = RunGit(['config', self._PatchsetSetting()],
                        error_ok=True).strip()
      if patchset:
        self.patchset = patchset
      else:
        self.patchset = None
      self.has_patchset = True
    return self.patchset

  def SetPatchset(self, patchset):
    """Set this branch's patchset.  If patchset=0, clears the patchset."""
    if patchset:
      RunGit(['config', self._PatchsetSetting(), str(patchset)])
    else:
      RunGit(['config', '--unset', self._PatchsetSetting()],
             swallow_stderr=True, error_ok=True)
    self.has_patchset = False

  def SetIssue(self, issue):
    """Set this branch's issue.  If issue=0, clears the issue."""
    if issue:
      RunGit(['config', self._IssueSetting(), str(issue)])
      if self.rietveld_server:
        RunGit(['config', self._RietveldServer(), self.rietveld_server])
    else:
      RunGit(['config', '--unset', self._IssueSetting()])
      self.SetPatchset(0)
    self.has_issue = False

  def CloseIssue(self):
    rpc_server = self._RpcServer()
    # Newer versions of Rietveld require us to pass an XSRF token to POST, so
    # we fetch it from the server.  (The version used by Chromium has been
    # modified so the token isn't required when closing an issue.)
    xsrf_token = rpc_server.Send('/xsrf_token',
                                 extra_headers={'X-Requesting-XSRF-Token': '1'})

    # You cannot close an issue with a GET.
    # We pass an empty string for the data so it is a POST rather than a GET.
    data = [("description", self.description),
            ("xsrf_token", xsrf_token)]
    ctype, body = upload.EncodeMultipartFormData(data, [])
    rpc_server.Send('/' + self.GetIssue() + '/close', body, ctype)

  def _RpcServer(self):
    """Returns an upload.RpcServer() to access this review's rietveld instance.
    """
    server = self.GetRietveldServer()
    return upload.GetRpcServer(server, save_cookies=True)

  def _IssueSetting(self):
    """Return the git setting that stores this change's issue."""
    return 'branch.%s.rietveldissue' % self.GetBranch()

  def _PatchsetSetting(self):
    """Return the git setting that stores this change's most recent patchset."""
    return 'branch.%s.rietveldpatchset' % self.GetBranch()

  def _RietveldServer(self):
    """Returns the git setting that stores this change's rietveld server."""
    return 'branch.%s.rietveldserver' % self.GetBranch()


def GetCodereviewSettingsInteractively():
  """Prompt the user for settings."""
  server = settings.GetDefaultServerUrl(error_ok=True)
  prompt = 'Rietveld server (host[:port])'
  prompt += ' [%s]' % (server or DEFAULT_SERVER)
  newserver = raw_input(prompt + ': ')
  if not server and not newserver:
    newserver = DEFAULT_SERVER
  if newserver and newserver != server:
    RunGit(['config', 'rietveld.server', newserver])

  def SetProperty(initial, caption, name):
    prompt = caption
    if initial:
      prompt += ' ("x" to clear) [%s]' % initial
    new_val = raw_input(prompt + ': ')
    if new_val == 'x':
      RunGit(['config', '--unset-all', 'rietveld.' + name], error_ok=True)
    elif new_val and new_val != initial:
      RunGit(['config', 'rietveld.' + name, new_val])

  SetProperty(settings.GetCCList(), 'CC list', 'cc')
  SetProperty(settings.GetTreeStatusUrl(error_ok=True), 'Tree status URL',
              'tree-status-url')
  SetProperty(settings.GetViewVCUrl(), 'ViewVC URL', 'viewvc-url')

  # TODO: configure a default branch to diff against, rather than this
  # svn-based hackery.


def FindCodereviewSettingsFile(filename='codereview.settings'):
  """Finds the given file starting in the cwd and going up.

  Only looks up to the top of the repository unless an
  'inherit-review-settings-ok' file exists in the root of the repository.
  """
  inherit_ok_file = 'inherit-review-settings-ok'
  cwd = os.getcwd()
  root = os.path.abspath(RunGit(['rev-parse', '--show-cdup']).strip())
  if os.path.isfile(os.path.join(root, inherit_ok_file)):
    root = '/'
  while True:
    if filename in os.listdir(cwd):
      if os.path.isfile(os.path.join(cwd, filename)):
        return open(os.path.join(cwd, filename))
    if cwd == root:
      break
    cwd = os.path.dirname(cwd)


def LoadCodereviewSettingsFromFile(fileobj):
  """Parse a codereview.settings file and updates hooks."""
  def DownloadToFile(url, filename):
    filename = os.path.join(settings.GetRoot(), filename)
    contents = urllib2.urlopen(url).read()
    fileobj = open(filename, 'w')
    fileobj.write(contents)
    fileobj.close()
    os.chmod(filename, 0755)
    return 0

  keyvals = {}
  for line in fileobj.read().splitlines():
    if not line or line.startswith("#"):
      continue
    k, v = line.split(": ", 1)
    keyvals[k] = v

  def GetProperty(name):
    return keyvals.get(name)

  def SetProperty(name, setting, unset_error_ok=False):
    fullname = 'rietveld.' + name
    if setting in keyvals:
      RunGit(['config', fullname, keyvals[setting]])
    else:
      RunGit(['config', '--unset-all', fullname], error_ok=unset_error_ok)

  SetProperty('server', 'CODE_REVIEW_SERVER')
  # Only server setting is required. Other settings can be absent.
  # In that case, we ignore errors raised during option deletion attempt.
  SetProperty('cc', 'CC_LIST', unset_error_ok=True)
  SetProperty('tree-status-url', 'STATUS', unset_error_ok=True)
  SetProperty('viewvc-url', 'VIEW_VC', unset_error_ok=True)

  if 'PUSH_URL_CONFIG' in keyvals and 'ORIGIN_URL_CONFIG' in keyvals:
    #should be of the form
    #PUSH_URL_CONFIG: url.ssh://gitrw.chromium.org.pushinsteadof
    #ORIGIN_URL_CONFIG: http://src.chromium.org/git
    RunGit(['config', keyvals['PUSH_URL_CONFIG'],
            keyvals['ORIGIN_URL_CONFIG']])

  # Update the hooks if the local hook files aren't present already.
  if GetProperty('GITCL_PREUPLOAD') and not os.path.isfile(PREUPLOAD_HOOK):
    DownloadToFile(GetProperty('GITCL_PREUPLOAD'), PREUPLOAD_HOOK)
  if GetProperty('GITCL_PREDCOMMIT') and not os.path.isfile(PREDCOMMIT_HOOK):
    DownloadToFile(GetProperty('GITCL_PREDCOMMIT'), PREDCOMMIT_HOOK)
  return 0


@usage('[repo root containing codereview.settings]')
def CMDconfig(parser, args):
  """edit configuration for this tree"""

  (options, args) = parser.parse_args(args)
  if len(args) == 0:
    GetCodereviewSettingsInteractively()
    return 0

  url = args[0]
  if not url.endswith('codereview.settings'):
    url = os.path.join(url, 'codereview.settings')

  # Load code review settings and download hooks (if available).
  LoadCodereviewSettingsFromFile(urllib2.urlopen(url))
  return 0


def CMDstatus(parser, args):
  """show status of changelists"""
  parser.add_option('--field',
                    help='print only specific field (desc|id|patch|url)')
  (options, args) = parser.parse_args(args)

  # TODO: maybe make show_branches a flag if necessary.
  show_branches = not options.field

  if show_branches:
    branches = RunGit(['for-each-ref', '--format=%(refname)', 'refs/heads'])
    if branches:
      print 'Branches associated with reviews:'
      for branch in sorted(branches.splitlines()):
        cl = Changelist(branchref=branch)
        print "  %10s: %s" % (cl.GetBranch(), cl.GetIssue())

  cl = Changelist()
  if options.field:
    if options.field.startswith('desc'):
      print cl.GetDescription()
    elif options.field == 'id':
      issueid = cl.GetIssue()
      if issueid:
        print issueid
    elif options.field == 'patch':
      patchset = cl.GetPatchset()
      if patchset:
        print patchset
    elif options.field == 'url':
      url = cl.GetIssueURL()
      if url:
        print url
  else:
    print
    print 'Current branch:',
    if not cl.GetIssue():
      print 'no issue assigned.'
      return 0
    print cl.GetBranch()
    print 'Issue number:', cl.GetIssue(), '(%s)' % cl.GetIssueURL()
    print 'Issue description:'
    print cl.GetDescription(pretty=True)
  return 0


@usage('[issue_number]')
def CMDissue(parser, args):
  """Set or display the current code review issue number.

  Pass issue number 0 to clear the current issue.
"""
  (options, args) = parser.parse_args(args)

  cl = Changelist()
  if len(args) > 0:
    try:
      issue = int(args[0])
    except ValueError:
      DieWithError('Pass a number to set the issue or none to list it.\n'
          'Maybe you want to run git cl status?')
    cl.SetIssue(issue)
  print 'Issue number:', cl.GetIssue(), '(%s)' % cl.GetIssueURL()
  return 0


def CreateDescriptionFromLog(args):
  """Pulls out the commit log to use as a base for the CL description."""
  log_args = []
  if len(args) == 1 and not args[0].endswith('.'):
    log_args = [args[0] + '..']
  elif len(args) == 1 and args[0].endswith('...'):
    log_args = [args[0][:-1]]
  elif len(args) == 2:
    log_args = [args[0] + '..' + args[1]]
  else:
    log_args = args[:]  # Hope for the best!
  return RunGit(['log', '--pretty=format:%s\n\n%b'] + log_args)


def UserEditedLog(starting_text):
  """Given some starting text, let the user edit it and return the result."""
  editor = os.getenv('EDITOR', 'vi')

  (file_handle, filename) = tempfile.mkstemp()
  fileobj = os.fdopen(file_handle, 'w')
  fileobj.write(starting_text)
  fileobj.close()

  ret = subprocess.call(editor + ' ' + filename, shell=True)
  if ret != 0:
    os.remove(filename)
    return

  fileobj = open(filename)
  text = fileobj.read()
  fileobj.close()
  os.remove(filename)
  stripcomment_re = re.compile(r'^#.*$', re.MULTILINE)
  return stripcomment_re.sub('', text).strip()


def RunHook(hook, upstream_branch, error_ok=False):
  """Run a given hook if it exists. By default, we fail on errors."""
  hook = '%s/%s' % (settings.GetRoot(), hook)
  if not os.path.exists(hook):
    return
  return RunCommand([hook, upstream_branch], error_ok=error_ok,
                    redirect_stdout=False)


def CMDpresubmit(parser, args):
  """run presubmit tests on the current changelist"""
  parser.add_option('--upload', action='store_true',
                    help='Run upload hook instead of the push/dcommit hook')
  (options, args) = parser.parse_args(args)

  # Make sure index is up-to-date before running diff-index.
  RunGit(['update-index', '--refresh', '-q'], error_ok=True)
  if RunGit(['diff-index', 'HEAD']):
    # TODO(maruel): Is this really necessary?
    print 'Cannot presubmit with a dirty tree.  You must commit locally first.'
    return 1

  if args:
    base_branch = args[0]
  else:
    # Default to diffing against the "upstream" branch.
    base_branch = Changelist().GetUpstreamBranch()

  if options.upload:
    print '*** Presubmit checks for UPLOAD would report: ***'
    return not RunHook(PREUPLOAD_HOOK, upstream_branch=base_branch,
        error_ok=True)
  else:
    print '*** Presubmit checks for DCOMMIT would report: ***'
    return not RunHook(PREDCOMMIT_HOOK, upstream_branch=base_branch,
        error_ok=True)


@usage('[args to "git diff"]')
def CMDupload(parser, args):
  """upload the current changelist to codereview"""
  parser.add_option('--bypass-hooks', action='store_true', dest='bypass_hooks',
                    help='bypass upload presubmit hook')
  parser.add_option('-m', dest='message', help='message for patch')
  parser.add_option('-r', '--reviewers',
                    help='reviewer email addresses')
  parser.add_option('--send-mail', action='store_true',
                    help='send email to reviewer immediately')
  parser.add_option("--emulate_svn_auto_props", action="store_true",
                    dest="emulate_svn_auto_props",
                    help="Emulate Subversion's auto properties feature.")
  parser.add_option("--desc_from_logs", action="store_true",
                    dest="from_logs",
                    help="""Squashes git commit logs into change description and
                            uses message as subject""")
  (options, args) = parser.parse_args(args)

  # Make sure index is up-to-date before running diff-index.
  RunGit(['update-index', '--refresh', '-q'], error_ok=True)
  if RunGit(['diff-index', 'HEAD']):
    print 'Cannot upload with a dirty tree.  You must commit locally first.'
    return 1

  cl = Changelist()
  if args:
    base_branch = args[0]
  else:
    # Default to diffing against the "upstream" branch.
    base_branch = cl.GetUpstreamBranch()
    args = [base_branch + "..."]

  if not options.bypass_hooks:
    RunHook(PREUPLOAD_HOOK, upstream_branch=base_branch, error_ok=False)

  # --no-ext-diff is broken in some versions of Git, so try to work around
  # this by overriding the environment (but there is still a problem if the
  # git config key "diff.external" is used).
  env = os.environ.copy()
  if 'GIT_EXTERNAL_DIFF' in env:
    del env['GIT_EXTERNAL_DIFF']
  subprocess.call(['git', 'diff', '--no-ext-diff', '--stat', '-M'] + args,
                  env=env)

  upload_args = ['--assume_yes']  # Don't ask about untracked files.
  upload_args.extend(['--server', cl.GetRietveldServer()])
  if options.reviewers:
    upload_args.extend(['--reviewers', options.reviewers])
  upload_args.extend(['--cc', settings.GetCCList()])
  if options.emulate_svn_auto_props:
    upload_args.append('--emulate_svn_auto_props')
  if options.send_mail:
    if not options.reviewers:
      DieWithError("Must specify reviewers to send email.")
    upload_args.append('--send_mail')
  if options.from_logs and not options.message:
    print 'Must set message for subject line if using desc_from_logs'
    return 1

  change_desc = None

  if cl.GetIssue():
    if options.message:
      upload_args.extend(['--message', options.message])
    upload_args.extend(['--issue', cl.GetIssue()])
    print ("This branch is associated with issue %s. "
           "Adding patch to that issue." % cl.GetIssue())
  else:
    log_desc = CreateDescriptionFromLog(args)
    if options.from_logs:
      # Uses logs as description and message as subject.
      subject = options.message
      change_desc = subject + '\n\n' + log_desc
    else:
      initial_text = """# Enter a description of the change.
# This will displayed on the codereview site.
# The first line will also be used as the subject of the review.
"""
      if 'BUG=' not in log_desc:
        log_desc += '\nBUG='
      if 'TEST=' not in log_desc:
        log_desc += '\nTEST='
      change_desc = UserEditedLog(initial_text + log_desc)
      subject = ''
      if change_desc:
        subject = change_desc.splitlines()[0]
    if not change_desc:
      print "Description is empty; aborting."
      return 1
    upload_args.extend(['--message', subject])
    upload_args.extend(['--description', change_desc])

  # Include the upstream repo's URL in the change -- this is useful for
  # projects that have their source spread across multiple repos.
  remote_url = None
  if settings.GetIsGitSvn():
    data = RunGit(['svn', 'info'])
    if data:
      keys = dict(line.split(': ', 1) for line in data.splitlines()
                  if ': ' in line)
      remote_url = keys.get('URL', None)
  else:
    if cl.GetRemoteUrl() and '/' in cl.GetUpstreamBranch():
      remote_url = (cl.GetRemoteUrl() + '@'
                    + cl.GetUpstreamBranch().split('/')[-1])
  if remote_url:
    upload_args.extend(['--base_url', remote_url])

  try:
    issue, patchset = upload.RealMain(['upload'] + upload_args + args)
  except:
    # If we got an exception after the user typed a description for their
    # change, back up the description before re-raising.
    if change_desc:
      backup_path = os.path.expanduser(DESCRIPTION_BACKUP_FILE)
      print '\nGot exception while uploading -- saving description to %s\n' \
          % backup_path
      backup_file = open(backup_path, 'w')
      backup_file.write(change_desc)
      backup_file.close()
    raise

  if not cl.GetIssue():
    cl.SetIssue(issue)
  cl.SetPatchset(patchset)
  return 0


def SendUpstream(parser, args, cmd):
  """Common code for CmdPush and CmdDCommit

  Squashed commit into a single.
  Updates changelog with metadata (e.g. pointer to review).
  Pushes/dcommits the code upstream.
  Updates review and closes.
  """
  parser.add_option('--bypass-hooks', action='store_true', dest='bypass_hooks',
                    help='bypass upload presubmit hook')
  parser.add_option('-m', dest='message',
                    help="override review description")
  parser.add_option('-f', action='store_true', dest='force',
                    help="force yes to questions (don't prompt)")
  parser.add_option('-c', dest='contributor',
                    help="external contributor for patch (appended to " +
                         "description and used as author for git). Should be " +
                         "formatted as 'First Last <email@example.com>'")
  parser.add_option('--tbr', action='store_true', dest='tbr',
                    help="short for 'to be reviewed', commit branch " +
                         "even without uploading for review")
  (options, args) = parser.parse_args(args)
  cl = Changelist()

  if not args or cmd == 'push':
    # Default to merging against our best guess of the upstream branch.
    args = [cl.GetUpstreamBranch()]

  base_branch = args[0]

  # Make sure index is up-to-date before running diff-index.
  RunGit(['update-index', '--refresh', '-q'], error_ok=True)
  if RunGit(['diff-index', 'HEAD']):
    print 'Cannot %s with a dirty tree.  You must commit locally first.' % cmd
    return 1

  # This rev-list syntax means "show all commits not in my branch that
  # are in base_branch".
  upstream_commits = RunGit(['rev-list', '^' + cl.GetBranchRef(),
                             base_branch]).splitlines()
  if upstream_commits:
    print ('Base branch "%s" has %d commits '
           'not in this branch.' % (base_branch, len(upstream_commits)))
    print 'Run "git merge %s" before attempting to %s.' % (base_branch, cmd)
    return 1

  if cmd == 'dcommit':
    # This is the revision `svn dcommit` will commit on top of.
    svn_head = RunGit(['log', '--grep=^git-svn-id:', '-1',
                       '--pretty=format:%H'])
    extra_commits = RunGit(['rev-list', '^' + svn_head, base_branch])
    if extra_commits:
      print ('This branch has %d additional commits not upstreamed yet.'
             % len(extra_commits.splitlines()))
      print ('Upstream "%s" or rebase this branch on top of the upstream trunk '
             'before attempting to %s.' % (base_branch, cmd))
      return 1

  if not options.force and not options.bypass_hooks:
    RunHook(PREDCOMMIT_HOOK, upstream_branch=base_branch, error_ok=False)

    if cmd == 'dcommit':
      # Check the tree status if the tree status URL is set.
      status = GetTreeStatus()
      if 'closed' == status:
        print ('The tree is closed.  Please wait for it to reopen. Use '
               '"git cl dcommit -f" to commit on a closed tree.')
        return 1
      elif 'unknown' == status:
        print ('Unable to determine tree status.  Please verify manually and '
               'use "git cl dcommit -f" to commit on a closed tree.')

  description = options.message
  if not options.tbr:
    # It is important to have these checks early.  Not only for user
    # convenience, but also because the cl object then caches the correct values
    # of these fields even as we're juggling branches for setting up the commit.
    if not cl.GetIssue():
      print 'Current issue unknown -- has this branch been uploaded?'
      print 'Use --tbr to commit without review.'
      return 1

    if not description:
      description = cl.GetDescription()

    if not description:
      print 'No description set.'
      print 'Visit %s/edit to set it.' % (cl.GetIssueURL())
      return 1

    description += "\n\nReview URL: %s" % cl.GetIssueURL()
  else:
    if not description:
      # Submitting TBR.  See if there's already a description in Rietveld, else
      # create a template description. Eitherway, give the user a chance to edit
      # it to fill in the TBR= field.
      if cl.GetIssue():
        description = cl.GetDescription()

      if not description:
        description = """# Enter a description of the change.
# This will be used as the change log for the commit.

"""
        description += CreateDescriptionFromLog(args)

      description = UserEditedLog(description + '\nTBR=')

    if not description:
      print "Description empty; aborting."
      return 1

  if options.contributor:
    if not re.match('^.*\s<\S+@\S+>$', options.contributor):
      print "Please provide contibutor as 'First Last <email@example.com>'"
      return 1
    description += "\nPatch from %s." % options.contributor
  print 'Description:', repr(description)

  branches = [base_branch, cl.GetBranchRef()]
  if not options.force:
    subprocess.call(['git', 'diff', '--stat'] + branches)
    raw_input("About to commit; enter to confirm.")

  # We want to squash all this branch's commits into one commit with the
  # proper description.
  # We do this by doing a "merge --squash" into a new commit branch, then
  # dcommitting that.
  MERGE_BRANCH = 'git-cl-commit'
  # Delete the merge branch if it already exists.
  if RunGitWithCode(['show-ref', '--quiet', '--verify',
                     'refs/heads/' + MERGE_BRANCH])[0] == 0:
    RunGit(['branch', '-D', MERGE_BRANCH])

  # We might be in a directory that's present in this branch but not in the
  # trunk.  Move up to the top of the tree so that git commands that expect a
  # valid CWD won't fail after we check out the merge branch.
  rel_base_path = RunGit(['rev-parse', '--show-cdup']).strip()
  if rel_base_path:
    os.chdir(rel_base_path)

  # Stuff our change into the merge branch.
  # We wrap in a try...finally block so if anything goes wrong,
  # we clean up the branches.
  retcode = -1
  try:
    RunGit(['checkout', '-q', '-b', MERGE_BRANCH, base_branch])
    RunGit(['merge', '--squash', cl.GetBranchRef()])
    if options.contributor:
      RunGit(['commit', '--author', options.contributor, '-m', description])
    else:
      RunGit(['commit', '-m', description])
    if cmd == 'push':
      # push the merge branch.
      remote, branch = cl.FetchUpstreamTuple()
      retcode, output = RunGitWithCode(
          ['push', '--porcelain', remote, 'HEAD:%s' % branch])
      logging.debug(output)
    else:
      # dcommit the merge branch.
      retcode, output = RunGitWithCode(['svn', 'dcommit', '--no-rebase'])
  finally:
    # And then swap back to the original branch and clean up.
    RunGit(['checkout', '-q', cl.GetBranch()])
    RunGit(['branch', '-D', MERGE_BRANCH])

  if cl.GetIssue():
    if cmd == 'dcommit' and 'Committed r' in output:
      revision = re.match('.*?\nCommitted r(\\d+)', output, re.DOTALL).group(1)
    elif cmd == 'push' and retcode == 0:
      match = (re.match(r'.*?([a-f0-9]{7})\.\.([a-f0-9]{7})$', l)
               for l in output.splitlines(False))
      match = filter(None, match)
      if len(match) != 1:
        DieWithError("Couldn't parse ouput to extract the committed hash:\n%s" %
            output)
      revision = match[0].group(2)
    else:
      return 1
    viewvc_url = settings.GetViewVCUrl()
    if viewvc_url and revision:
      cl.description += ('\n\nCommitted: ' + viewvc_url + revision)
    print ('Closing issue '
           '(you may be prompted for your codereview password)...')
    cl.CloseIssue()
    cl.SetIssue(0)

  if retcode == 0:
    hook = POSTUPSTREAM_HOOK_PATTERN % cmd
    if os.path.isfile(hook):
      RunHook(hook, upstream_branch=base_branch, error_ok=True)

  return 0


@usage('[upstream branch to apply against]')
def CMDdcommit(parser, args):
  """commit the current changelist via git-svn"""
  if not settings.GetIsGitSvn():
    print('This doesn\'t appear to be an SVN repository.')
    print('Are you sure you didn\'t mean \'git cl push\'?')
    raw_input('[Press enter to dcommit or ctrl-C to quit]')
  return SendUpstream(parser, args, 'dcommit')


@usage('[upstream branch to apply against]')
def CMDpush(parser, args):
  """commit the current changelist via git"""
  if settings.GetIsGitSvn():
    print('This appears to be an SVN repository.')
    print('Are you sure you didn\'t mean \'git cl dcommit\'?')
    raw_input('[Press enter to push or ctrl-C to quit]')
  return SendUpstream(parser, args, 'push')


@usage('<patch url or issue id>')
def CMDpatch(parser, args):
  """patch in a code review"""
  parser.add_option('-b', dest='newbranch',
                    help='create a new branch off trunk for the patch')
  parser.add_option('-f', action='store_true', dest='force',
                    help='with -b, clobber any existing branch')
  parser.add_option('--reject', action='store_true', dest='reject',
                    help='allow failed patches and spew .rej files')
  parser.add_option('-n', '--no-commit', action='store_true', dest='nocommit',
                    help="don't commit after patch applies")
  (options, args) = parser.parse_args(args)
  if len(args) != 1:
    parser.print_help()
    return 1
  input = args[0]

  if re.match(r'\d+', input):
    # Input is an issue id.  Figure out the URL.
    issue = input
    server = settings.GetDefaultServerUrl()
    fetch = urllib2.urlopen('%s/%s' % (server, issue)).read()
    m = re.search(r'/download/issue[0-9]+_[0-9]+.diff', fetch)
    if not m:
      DieWithError('Must pass an issue ID or full URL for '
          '\'Download raw patch set\'')
    url = '%s%s' % (server, m.group(0).strip())
  else:
    # Assume it's a URL to the patch. Default to http.
    input = FixUrl(input)
    match = re.match(r'.*?/issue(\d+)_\d+.diff', input)
    if match:
      issue = match.group(1)
      url = input
    else:
      DieWithError('Must pass an issue ID or full URL for '
          '\'Download raw patch set\'')

  if options.newbranch:
    if options.force:
      RunGit(['branch', '-D', options.newbranch],
         swallow_stderr=True, error_ok=True)
    RunGit(['checkout', '-b', options.newbranch,
            Changelist().GetUpstreamBranch()])

  # Switch up to the top-level directory, if necessary, in preparation for
  # applying the patch.
  top = RunGit(['rev-parse', '--show-cdup']).strip()
  if top:
    os.chdir(top)

  patch_data = urllib2.urlopen(url).read()
  # Git patches have a/ at the beginning of source paths.  We strip that out
  # with a sed script rather than the -p flag to patch so we can feed either
  # Git or svn-style patches into the same apply command.
  # re.sub() should be used but flags=re.MULTILINE is only in python 2.7.
  sed_proc = Popen(['sed', '-e', 's|^--- a/|--- |; s|^+++ b/|+++ |'],
      stdin=subprocess.PIPE, stdout=subprocess.PIPE)
  patch_data = sed_proc.communicate(patch_data)[0]
  if sed_proc.returncode:
    DieWithError('Git patch mungling failed.')
  logging.info(patch_data)
  # We use "git apply" to apply the patch instead of "patch" so that we can
  # pick up file adds.
  # The --index flag means: also insert into the index (so we catch adds).
  cmd = ['git', 'apply', '--index', '-p0']
  if options.reject:
    cmd.append('--reject')
  patch_proc = Popen(cmd, stdin=subprocess.PIPE)
  patch_proc.communicate(patch_data)
  if patch_proc.returncode:
    DieWithError('Failed to apply the patch')

  # If we had an issue, commit the current state and register the issue.
  if not options.nocommit:
    RunGit(['commit', '-m', 'patch from issue %s' % issue])
    cl = Changelist()
    cl.SetIssue(issue)
    print "Committed patch."
  else:
    print "Patch applied to index."
  return 0


def CMDrebase(parser, args):
  """rebase current branch on top of svn repo"""
  # Provide a wrapper for git svn rebase to help avoid accidental
  # git svn dcommit.
  # It's the only command that doesn't use parser at all since we just defer
  # execution to git-svn.
  RunGit(['svn', 'rebase'] + args, redirect_stdout=False)
  return 0


def GetTreeStatus():
  """Fetches the tree status and returns either 'open', 'closed',
  'unknown' or 'unset'."""
  url = settings.GetTreeStatusUrl(error_ok=True)
  if url:
    status = urllib2.urlopen(url).read().lower()
    if status.find('closed') != -1 or status == '0':
      return 'closed'
    elif status.find('open') != -1 or status == '1':
      return 'open'
    return 'unknown'

  return 'unset'

def GetTreeStatusReason():
  """Fetches the tree status from a json url and returns the message
  with the reason for the tree to be opened or closed."""
  # Don't import it at file level since simplejson is not installed by default
  # on python 2.5 and it is only used for git-cl tree which isn't often used,
  # forcing everyone to install simplejson isn't efficient.
  try:
    import simplejson as json
  except ImportError:
    try:
      import json
      # Some versions of python2.5 have an incomplete json module. Check to make
      # sure loads exists.
      json.loads
    except (ImportError, AttributeError):
      print >> sys.stderr, 'Please install simplejson'
      sys.exit(1)

  json_url = 'http://chromium-status.appspot.com/current?format=json'
  connection = urllib2.urlopen(json_url)
  status = json.loads(connection.read())
  connection.close()
  return status['message']

def CMDtree(parser, args):
  """show the status of the tree"""
  (options, args) = parser.parse_args(args)
  status = GetTreeStatus()
  if 'unset' == status:
    print 'You must configure your tree status URL by running "git cl config".'
    return 2

  print "The tree is %s" % status
  print
  print GetTreeStatusReason()
  if status != 'open':
    return 1
  return 0


def CMDupstream(parser, args):
  """print the name of the upstream branch, if any"""
  (options, args) = parser.parse_args(args)
  cl = Changelist()
  print cl.GetUpstreamBranch()
  return 0


def Command(name):
  return getattr(sys.modules[__name__], 'CMD' + name, None)


def CMDhelp(parser, args):
  """print list of commands or help for a specific command"""
  (options, args) = parser.parse_args(args)
  if len(args) == 1:
    return main(args + ['--help'])
  parser.print_help()
  return 0


def GenUsage(parser, command):
  """Modify an OptParse object with the function's documentation."""
  obj = Command(command)
  more = getattr(obj, 'usage_more', '')
  if command == 'help':
    command = '<command>'
  else:
    # OptParser.description prefer nicely non-formatted strings.
    parser.description = re.sub('[\r\n ]{2,}', ' ', obj.__doc__)
  parser.set_usage('usage: %%prog %s [options] %s' % (command, more))


def main(argv):
  """Doesn't parse the arguments here, just find the right subcommand to
  execute."""
  # Do it late so all commands are listed.
  CMDhelp.usage_more = ('\n\nCommands are:\n' + '\n'.join([
      '  %-10s %s' % (fn[3:], Command(fn[3:]).__doc__.split('\n')[0].strip())
      for fn in dir(sys.modules[__name__]) if fn.startswith('CMD')]))

  # Create the option parse and add --verbose support.
  parser = optparse.OptionParser()
  parser.add_option('-v', '--verbose', action='store_true')
  old_parser_args = parser.parse_args
  def Parse(args):
    options, args = old_parser_args(args)
    if options.verbose:
      logging.basicConfig(level=logging.DEBUG)
    else:
      logging.basicConfig(level=logging.WARNING)
    return options, args
  parser.parse_args = Parse

  if argv:
    command = Command(argv[0])
    if command:
      # "fix" the usage and the description now that we know the subcommand.
      GenUsage(parser, argv[0])
      try:
        return command(parser, argv[1:])
      except urllib2.HTTPError, e:
        if e.code != 500:
          raise
        DieWithError(
            ('AppEngine is misbehaving and returned HTTP %d, again. Keep faith '
             'and retry or visit go/isgaeup.\n%s') % (e.code, str(e)))

  # Not a known command. Default to help.
  GenUsage(parser, 'help')
  return CMDhelp(parser, argv)


if __name__ == '__main__':
  sys.exit(main(sys.argv[1:]))