#
# Copyright (C) 2008 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import print_function
import json
import netrc
from optparse import SUPPRESS_HELP
import os
import re
import shutil
import socket
import subprocess
import sys
import tempfile
import time

from pyversion import is_python3
if is_python3():
  import http.cookiejar as cookielib
  import urllib.error
  import urllib.parse
  import urllib.request
  import xmlrpc.client
else:
  import cookielib
  import imp
  import urllib2
  import urlparse
  import xmlrpclib
  urllib = imp.new_module('urllib')
  urllib.error = urllib2
  urllib.parse = urlparse
  urllib.request = urllib2
  xmlrpc = imp.new_module('xmlrpc')
  xmlrpc.client = xmlrpclib

try:
  import threading as _threading
except ImportError:
  import dummy_threading as _threading

try:
  import resource
  def _rlimit_nofile():
    return resource.getrlimit(resource.RLIMIT_NOFILE)
except ImportError:
  def _rlimit_nofile():
    return (256, 256)

try:
  import multiprocessing
except ImportError:
  multiprocessing = None

import event_log
from git_command import GIT, git_require
from git_config import GetUrlCookieFile
from git_refs import R_HEADS, HEAD
import gitc_utils
from project import Project
from project import RemoteSpec
from command import Command, MirrorSafeCommand
from error import RepoChangedException, GitError, ManifestParseError
from project import SyncBuffer
from progress import Progress
from wrapper import Wrapper
from manifest_xml import GitcManifest

_ONE_DAY_S = 24 * 60 * 60

class _FetchError(Exception):
  """Internal error thrown in _FetchHelper() when we don't want stack trace."""
  pass

class Sync(Command, MirrorSafeCommand):
  jobs = 1
  common = True
  helpSummary = "Update working tree to the latest revision"
  helpUsage = """
%prog [<project>...]
"""
  helpDescription = """
The '%prog' command synchronizes local project directories
with the remote repositories specified in the manifest.  If a local
project does not yet exist, it will clone a new local directory from
the remote repository and set up tracking branches as specified in
the manifest.  If the local project already exists, '%prog'
will update the remote branches and rebase any new local changes
on top of the new remote changes.

'%prog' will synchronize all projects listed at the command
line.  Projects can be specified either by name, or by a relative
or absolute path to the project's local directory. If no projects
are specified, '%prog' will synchronize all projects listed in
the manifest.

The -d/--detach option can be used to switch specified projects
back to the manifest revision.  This option is especially helpful
if the project is currently on a topic branch, but the manifest
revision is temporarily needed.

The -s/--smart-sync option can be used to sync to a known good
build as specified by the manifest-server element in the current
manifest. The -t/--smart-tag option is similar and allows you to
specify a custom tag/label.

The -u/--manifest-server-username and -p/--manifest-server-password
options can be used to specify a username and password to authenticate
with the manifest server when using the -s or -t option.

If -u and -p are not specified when using the -s or -t option, '%prog'
will attempt to read authentication credentials for the manifest server
from the user's .netrc file.

'%prog' will not use authentication credentials from -u/-p or .netrc
if the manifest server specified in the manifest file already includes
credentials.

The -f/--force-broken option can be used to proceed with syncing
other projects if a project sync fails.

The --force-sync option can be used to overwrite existing git
directories if they have previously been linked to a different
object direcotry. WARNING: This may cause data to be lost since
refs may be removed when overwriting.

The --no-clone-bundle option disables any attempt to use
$URL/clone.bundle to bootstrap a new Git repository from a
resumeable bundle file on a content delivery network. This
may be necessary if there are problems with the local Python
HTTP client or proxy configuration, but the Git binary works.

The --fetch-submodules option enables fetching Git submodules
of a project from server.

The -c/--current-branch option can be used to only fetch objects that
are on the branch specified by a project's revision.

The --optimized-fetch option can be used to only fetch projects that
are fixed to a sha1 revision if the sha1 revision does not already
exist locally.

The --prune option can be used to remove any refs that no longer
exist on the remote.

SSH Connections
---------------

If at least one project remote URL uses an SSH connection (ssh://,
git+ssh://, or user@host:path syntax) repo will automatically
enable the SSH ControlMaster option when connecting to that host.
This feature permits other projects in the same '%prog' session to
reuse the same SSH tunnel, saving connection setup overheads.

To disable this behavior on UNIX platforms, set the GIT_SSH
environment variable to 'ssh'.  For example:

  export GIT_SSH=ssh
  %prog

Compatibility
~~~~~~~~~~~~~

This feature is automatically disabled on Windows, due to the lack
of UNIX domain socket support.

This feature is not compatible with url.insteadof rewrites in the
user's ~/.gitconfig.  '%prog' is currently not able to perform the
rewrite early enough to establish the ControlMaster tunnel.

If the remote SSH daemon is Gerrit Code Review, version 2.0.10 or
later is required to fix a server side protocol bug.

"""

  def _Options(self, p, show_smart=True):
    try:
      self.jobs = self.manifest.default.sync_j
    except ManifestParseError:
      self.jobs = 1

    p.add_option('-f', '--force-broken',
                 dest='force_broken', action='store_true',
                 help="continue sync even if a project fails to sync")
    p.add_option('--force-sync',
                 dest='force_sync', action='store_true',
                 help="overwrite an existing git directory if it needs to "
                      "point to a different object directory. WARNING: this "
                      "may cause loss of data")
    p.add_option('-l', '--local-only',
                 dest='local_only', action='store_true',
                 help="only update working tree, don't fetch")
    p.add_option('-n', '--network-only',
                 dest='network_only', action='store_true',
                 help="fetch only, don't update working tree")
    p.add_option('-d', '--detach',
                 dest='detach_head', action='store_true',
                 help='detach projects back to manifest revision')
    p.add_option('-c', '--current-branch',
                 dest='current_branch_only', action='store_true',
                 help='fetch only current branch from server')
    p.add_option('-q', '--quiet',
                 dest='quiet', action='store_true',
                 help='be more quiet')
    p.add_option('-j', '--jobs',
                 dest='jobs', action='store', type='int',
                 help="projects to fetch simultaneously (default %d)" % self.jobs)
    p.add_option('-m', '--manifest-name',
                 dest='manifest_name',
                 help='temporary manifest to use for this sync', metavar='NAME.xml')
    p.add_option('--no-clone-bundle',
                 dest='no_clone_bundle', action='store_true',
                 help='disable use of /clone.bundle on HTTP/HTTPS')
    p.add_option('-u', '--manifest-server-username', action='store',
                 dest='manifest_server_username',
                 help='username to authenticate with the manifest server')
    p.add_option('-p', '--manifest-server-password', action='store',
                 dest='manifest_server_password',
                 help='password to authenticate with the manifest server')
    p.add_option('--fetch-submodules',
                 dest='fetch_submodules', action='store_true',
                 help='fetch submodules from server')
    p.add_option('--no-tags',
                 dest='no_tags', action='store_true',
                 help="don't fetch tags")
    p.add_option('--optimized-fetch',
                 dest='optimized_fetch', action='store_true',
                 help='only fetch projects fixed to sha1 if revision does not exist locally')
    p.add_option('--prune', dest='prune', action='store_true',
                 help='delete refs that no longer exist on the remote')
    if show_smart:
      p.add_option('-s', '--smart-sync',
                   dest='smart_sync', action='store_true',
                   help='smart sync using manifest from the latest known good build')
      p.add_option('-t', '--smart-tag',
                   dest='smart_tag', action='store',
                   help='smart sync using manifest from a known tag')

    g = p.add_option_group('repo Version options')
    g.add_option('--no-repo-verify',
                 dest='no_repo_verify', action='store_true',
                 help='do not verify repo source code')
    g.add_option('--repo-upgraded',
                 dest='repo_upgraded', action='store_true',
                 help=SUPPRESS_HELP)

  def _FetchProjectList(self, opt, projects, sem, *args, **kwargs):
    """Main function of the fetch threads when jobs are > 1.

    Delegates most of the work to _FetchHelper.

    Args:
      opt: Program options returned from optparse.  See _Options().
      projects: Projects to fetch.
      sem: We'll release() this semaphore when we exit so that another thread
          can be started up.
      *args, **kwargs: Remaining arguments to pass to _FetchHelper. See the
          _FetchHelper docstring for details.
    """
    try:
        for project in projects:
          success = self._FetchHelper(opt, project, *args, **kwargs)
          if not success and not opt.force_broken:
            break
    finally:
        sem.release()

  def _FetchHelper(self, opt, project, lock, fetched, pm, err_event):
    """Fetch git objects for a single project.

    Args:
      opt: Program options returned from optparse.  See _Options().
      project: Project object for the project to fetch.
      lock: Lock for accessing objects that are shared amongst multiple
          _FetchHelper() threads.
      fetched: set object that we will add project.gitdir to when we're done
          (with our lock held).
      pm: Instance of a Project object.  We will call pm.update() (with our
          lock held).
      err_event: We'll set this event in the case of an error (after printing
          out info about the error).

    Returns:
      Whether the fetch was successful.
    """
    # We'll set to true once we've locked the lock.
    did_lock = False

    if not opt.quiet:
      print('Fetching project %s' % project.name)

    # Encapsulate everything in a try/except/finally so that:
    # - We always set err_event in the case of an exception.
    # - We always make sure we call sem.release().
    # - We always make sure we unlock the lock if we locked it.
    start = time.time()
    success = False
    try:
      try:
        success = project.Sync_NetworkHalf(
          quiet=opt.quiet,
          current_branch_only=opt.current_branch_only,
          force_sync=opt.force_sync,
          clone_bundle=not opt.no_clone_bundle,
          no_tags=opt.no_tags, archive=self.manifest.IsArchive,
          optimized_fetch=opt.optimized_fetch,
          prune=opt.prune)
        self._fetch_times.Set(project, time.time() - start)

        # Lock around all the rest of the code, since printing, updating a set
        # and Progress.update() are not thread safe.
        lock.acquire()
        did_lock = True

        if not success:
          err_event.set()
          print('error: Cannot fetch %s from %s'
                % (project.name, project.remote.url),
                file=sys.stderr)
          if opt.force_broken:
            print('warn: --force-broken, continuing to sync',
                  file=sys.stderr)
          else:
            raise _FetchError()

        fetched.add(project.gitdir)
        pm.update()
      except _FetchError:
        pass
      except Exception as e:
        print('error: Cannot fetch %s (%s: %s)' \
            % (project.name, type(e).__name__, str(e)), file=sys.stderr)
        err_event.set()
        raise
    finally:
      if did_lock:
        lock.release()
      finish = time.time()
      self.event_log.AddSync(project, event_log.TASK_SYNC_NETWORK,
                             start, finish, success)

    return success

  def _Fetch(self, projects, opt):
    fetched = set()
    lock = _threading.Lock()
    pm = Progress('Fetching projects', len(projects),
                  print_newline=not(opt.quiet))

    objdir_project_map = dict()
    for project in projects:
      objdir_project_map.setdefault(project.objdir, []).append(project)

    threads = set()
    sem = _threading.Semaphore(self.jobs)
    err_event = _threading.Event()
    for project_list in objdir_project_map.values():
      # Check for any errors before running any more tasks.
      # ...we'll let existing threads finish, though.
      if err_event.isSet() and not opt.force_broken:
        break

      sem.acquire()
      kwargs = dict(opt=opt,
                    projects=project_list,
                    sem=sem,
                    lock=lock,
                    fetched=fetched,
                    pm=pm,
                    err_event=err_event)
      if self.jobs > 1:
        t = _threading.Thread(target = self._FetchProjectList,
                              kwargs = kwargs)
        # Ensure that Ctrl-C will not freeze the repo process.
        t.daemon = True
        threads.add(t)
        t.start()
      else:
        self._FetchProjectList(**kwargs)

    for t in threads:
      t.join()

    # If we saw an error, exit with code 1 so that other scripts can check.
    if err_event.isSet() and not opt.force_broken:
      print('\nerror: Exited sync due to fetch errors', file=sys.stderr)
      sys.exit(1)

    pm.end()
    self._fetch_times.Save()

    if not self.manifest.IsArchive:
      self._GCProjects(projects)

    return fetched

  def _GCProjects(self, projects):
    gc_gitdirs = {}
    for project in projects:
      if len(project.manifest.GetProjectsWithName(project.name)) > 1:
        print('Shared project %s found, disabling pruning.' % project.name)
        project.bare_git.config('--replace-all', 'gc.pruneExpire', 'never')
      gc_gitdirs[project.gitdir] = project.bare_git

    has_dash_c = git_require((1, 7, 2))
    if multiprocessing and has_dash_c:
      cpu_count = multiprocessing.cpu_count()
    else:
      cpu_count = 1
    jobs = min(self.jobs, cpu_count)

    if jobs < 2:
      for bare_git in gc_gitdirs.values():
        bare_git.gc('--auto')
      return

    config = {'pack.threads': cpu_count / jobs if cpu_count > jobs else 1}

    threads = set()
    sem = _threading.Semaphore(jobs)
    err_event = _threading.Event()

    def GC(bare_git):
      try:
        try:
          bare_git.gc('--auto', config=config)
        except GitError:
          err_event.set()
        except:
          err_event.set()
          raise
      finally:
        sem.release()

    for bare_git in gc_gitdirs.values():
      if err_event.isSet():
        break
      sem.acquire()
      t = _threading.Thread(target=GC, args=(bare_git,))
      t.daemon = True
      threads.add(t)
      t.start()

    for t in threads:
      t.join()

    if err_event.isSet():
      print('\nerror: Exited sync due to gc errors', file=sys.stderr)
      sys.exit(1)

  def _ReloadManifest(self, manifest_name=None):
    if manifest_name:
      # Override calls _Unload already
      self.manifest.Override(manifest_name)
    else:
      self.manifest._Unload()

  def _DeleteProject(self, path):
    print('Deleting obsolete path %s' % path, file=sys.stderr)

    # Delete the .git directory first, so we're less likely to have a partially
    # working git repository around. There shouldn't be any git projects here,
    # so rmtree works.
    try:
      shutil.rmtree(os.path.join(path, '.git'))
    except OSError:
      print('Failed to remove %s' % os.path.join(path, '.git'), file=sys.stderr)
      print('error: Failed to delete obsolete path %s' % path, file=sys.stderr)
      print('       remove manually, then run sync again', file=sys.stderr)
      return -1

    # Delete everything under the worktree, except for directories that contain
    # another git project
    dirs_to_remove = []
    failed = False
    for root, dirs, files in os.walk(path):
      for f in files:
        try:
          os.remove(os.path.join(root, f))
        except OSError:
          print('Failed to remove %s' % os.path.join(root, f), file=sys.stderr)
          failed = True
      dirs[:] = [d for d in dirs
                 if not os.path.lexists(os.path.join(root, d, '.git'))]
      dirs_to_remove += [os.path.join(root, d) for d in dirs
                         if os.path.join(root, d) not in dirs_to_remove]
    for d in reversed(dirs_to_remove):
      if os.path.islink(d):
        try:
          os.remove(d)
        except OSError:
          print('Failed to remove %s' % os.path.join(root, d), file=sys.stderr)
          failed = True
      elif len(os.listdir(d)) == 0:
        try:
          os.rmdir(d)
        except OSError:
          print('Failed to remove %s' % os.path.join(root, d), file=sys.stderr)
          failed = True
          continue
    if failed:
      print('error: Failed to delete obsolete path %s' % path, file=sys.stderr)
      print('       remove manually, then run sync again', file=sys.stderr)
      return -1

    # Try deleting parent dirs if they are empty
    project_dir = path
    while project_dir != self.manifest.topdir:
      if len(os.listdir(project_dir)) == 0:
        os.rmdir(project_dir)
      else:
        break
      project_dir = os.path.dirname(project_dir)

    return 0

  def UpdateProjectList(self):
    new_project_paths = []
    for project in self.GetProjects(None, missing_ok=True):
      if project.relpath:
        new_project_paths.append(project.relpath)
    file_name = 'project.list'
    file_path = os.path.join(self.manifest.repodir, file_name)
    old_project_paths = []

    if os.path.exists(file_path):
      fd = open(file_path, 'r')
      try:
        old_project_paths = fd.read().split('\n')
      finally:
        fd.close()
      for path in old_project_paths:
        if not path:
          continue
        if path not in new_project_paths:
          # If the path has already been deleted, we don't need to do it
          gitdir = os.path.join(self.manifest.topdir, path, '.git')
          if os.path.exists(gitdir):
            project = Project(
                           manifest = self.manifest,
                           name = path,
                           remote = RemoteSpec('origin'),
                           gitdir = gitdir,
                           objdir = gitdir,
                           worktree = os.path.join(self.manifest.topdir, path),
                           relpath = path,
                           revisionExpr = 'HEAD',
                           revisionId = None,
                           groups = None)

            if project.IsDirty():
              print('error: Cannot remove project "%s": uncommitted changes '
                    'are present' % project.relpath, file=sys.stderr)
              print('       commit changes, then run sync again',
                    file=sys.stderr)
              return -1
            elif self._DeleteProject(project.worktree):
              return -1

    new_project_paths.sort()
    fd = open(file_path, 'w')
    try:
      fd.write('\n'.join(new_project_paths))
      fd.write('\n')
    finally:
      fd.close()
    return 0

  def Execute(self, opt, args):
    if opt.jobs:
      self.jobs = opt.jobs
    if self.jobs > 1:
      soft_limit, _ = _rlimit_nofile()
      self.jobs = min(self.jobs, (soft_limit - 5) / 3)

    if opt.network_only and opt.detach_head:
      print('error: cannot combine -n and -d', file=sys.stderr)
      sys.exit(1)
    if opt.network_only and opt.local_only:
      print('error: cannot combine -n and -l', file=sys.stderr)
      sys.exit(1)
    if opt.manifest_name and opt.smart_sync:
      print('error: cannot combine -m and -s', file=sys.stderr)
      sys.exit(1)
    if opt.manifest_name and opt.smart_tag:
      print('error: cannot combine -m and -t', file=sys.stderr)
      sys.exit(1)
    if opt.manifest_server_username or opt.manifest_server_password:
      if not (opt.smart_sync or opt.smart_tag):
        print('error: -u and -p may only be combined with -s or -t',
              file=sys.stderr)
        sys.exit(1)
      if None in [opt.manifest_server_username, opt.manifest_server_password]:
        print('error: both -u and -p must be given', file=sys.stderr)
        sys.exit(1)

    if opt.manifest_name:
      self.manifest.Override(opt.manifest_name)

    manifest_name = opt.manifest_name
    smart_sync_manifest_name = "smart_sync_override.xml"
    smart_sync_manifest_path = os.path.join(
      self.manifest.manifestProject.worktree, smart_sync_manifest_name)

    if opt.smart_sync or opt.smart_tag:
      if not self.manifest.manifest_server:
        print('error: cannot smart sync: no manifest server defined in '
              'manifest', file=sys.stderr)
        sys.exit(1)

      manifest_server = self.manifest.manifest_server
      if not opt.quiet:
        print('Using manifest server %s' % manifest_server)

      if not '@' in manifest_server:
        username = None
        password = None
        if opt.manifest_server_username and opt.manifest_server_password:
          username = opt.manifest_server_username
          password = opt.manifest_server_password
        else:
          try:
            info = netrc.netrc()
          except IOError:
            # .netrc file does not exist or could not be opened
            pass
          else:
            try:
              parse_result = urllib.parse.urlparse(manifest_server)
              if parse_result.hostname:
                auth = info.authenticators(parse_result.hostname)
                if auth:
                  username, _account, password = auth
                else:
                  print('No credentials found for %s in .netrc'
                        % parse_result.hostname, file=sys.stderr)
            except netrc.NetrcParseError as e:
              print('Error parsing .netrc file: %s' % e, file=sys.stderr)

        if (username and password):
          manifest_server = manifest_server.replace('://', '://%s:%s@' %
                                                    (username, password),
                                                    1)

      transport = PersistentTransport(manifest_server)
      if manifest_server.startswith('persistent-'):
        manifest_server = manifest_server[len('persistent-'):]

      try:
        server = xmlrpc.client.Server(manifest_server, transport=transport)
        if opt.smart_sync:
          p = self.manifest.manifestProject
          b = p.GetBranch(p.CurrentBranch)
          branch = b.merge
          if branch.startswith(R_HEADS):
            branch = branch[len(R_HEADS):]

          env = os.environ.copy()
          if 'SYNC_TARGET' in env:
            target = env['SYNC_TARGET']
            [success, manifest_str] = server.GetApprovedManifest(branch, target)
          elif 'TARGET_PRODUCT' in env and 'TARGET_BUILD_VARIANT' in env:
            target = '%s-%s' % (env['TARGET_PRODUCT'],
                                env['TARGET_BUILD_VARIANT'])
            [success, manifest_str] = server.GetApprovedManifest(branch, target)
          else:
            [success, manifest_str] = server.GetApprovedManifest(branch)
        else:
          assert(opt.smart_tag)
          [success, manifest_str] = server.GetManifest(opt.smart_tag)

        if success:
          manifest_name = smart_sync_manifest_name
          try:
            f = open(smart_sync_manifest_path, 'w')
            try:
              f.write(manifest_str)
            finally:
              f.close()
          except IOError as e:
            print('error: cannot write manifest to %s:\n%s'
                  % (smart_sync_manifest_path, e),
                  file=sys.stderr)
            sys.exit(1)
          self._ReloadManifest(manifest_name)
        else:
          print('error: manifest server RPC call failed: %s' %
                manifest_str, file=sys.stderr)
          sys.exit(1)
      except (socket.error, IOError, xmlrpc.client.Fault) as e:
        print('error: cannot connect to manifest server %s:\n%s'
              % (self.manifest.manifest_server, e), file=sys.stderr)
        sys.exit(1)
      except xmlrpc.client.ProtocolError as e:
        print('error: cannot connect to manifest server %s:\n%d %s'
              % (self.manifest.manifest_server, e.errcode, e.errmsg),
              file=sys.stderr)
        sys.exit(1)
    else:  # Not smart sync or smart tag mode
      if os.path.isfile(smart_sync_manifest_path):
        try:
          os.remove(smart_sync_manifest_path)
        except OSError as e:
          print('error: failed to remove existing smart sync override manifest: %s' %
                e, file=sys.stderr)

    rp = self.manifest.repoProject
    rp.PreSync()

    mp = self.manifest.manifestProject
    mp.PreSync()

    if opt.repo_upgraded:
      _PostRepoUpgrade(self.manifest, quiet=opt.quiet)

    if not opt.local_only:
      start = time.time()
      success = mp.Sync_NetworkHalf(quiet=opt.quiet,
                                    current_branch_only=opt.current_branch_only,
                                    no_tags=opt.no_tags,
                                    optimized_fetch=opt.optimized_fetch,
                                    submodules=self.manifest.HasSubmodules)
      finish = time.time()
      self.event_log.AddSync(mp, event_log.TASK_SYNC_NETWORK,
                             start, finish, success)

    if mp.HasChanges:
      syncbuf = SyncBuffer(mp.config)
      start = time.time()
      mp.Sync_LocalHalf(syncbuf, submodules=self.manifest.HasSubmodules)
      clean = syncbuf.Finish()
      self.event_log.AddSync(mp, event_log.TASK_SYNC_LOCAL,
                             start, time.time(), clean)
      if not clean:
        sys.exit(1)
      self._ReloadManifest(manifest_name)
      if opt.jobs is None:
        self.jobs = self.manifest.default.sync_j

    if self.gitc_manifest:
      gitc_manifest_projects = self.GetProjects(args,
                                                missing_ok=True)
      gitc_projects = []
      opened_projects = []
      for project in gitc_manifest_projects:
        if project.relpath in self.gitc_manifest.paths and \
           self.gitc_manifest.paths[project.relpath].old_revision:
          opened_projects.append(project.relpath)
        else:
          gitc_projects.append(project.relpath)

      if not args:
        gitc_projects = None

      if gitc_projects != [] and not opt.local_only:
        print('Updating GITC client: %s' % self.gitc_manifest.gitc_client_name)
        manifest = GitcManifest(self.repodir, self.gitc_manifest.gitc_client_name)
        if manifest_name:
          manifest.Override(manifest_name)
        else:
          manifest.Override(self.manifest.manifestFile)
        gitc_utils.generate_gitc_manifest(self.gitc_manifest,
                                          manifest,
                                          gitc_projects)
        print('GITC client successfully synced.')

      # The opened projects need to be synced as normal, therefore we
      # generate a new args list to represent the opened projects.
      # TODO: make this more reliable -- if there's a project name/path overlap,
      # this may choose the wrong project.
      args = [os.path.relpath(self.manifest.paths[path].worktree, os.getcwd())
              for path in opened_projects]
      if not args:
        return
    all_projects = self.GetProjects(args,
                                    missing_ok=True,
                                    submodules_ok=opt.fetch_submodules)

    self._fetch_times = _FetchTimes(self.manifest)
    if not opt.local_only:
      to_fetch = []
      now = time.time()
      if _ONE_DAY_S <= (now - rp.LastFetch):
        to_fetch.append(rp)
      to_fetch.extend(all_projects)
      to_fetch.sort(key=self._fetch_times.Get, reverse=True)

      fetched = self._Fetch(to_fetch, opt)
      _PostRepoFetch(rp, opt.no_repo_verify)
      if opt.network_only:
        # bail out now; the rest touches the working tree
        return

      # Iteratively fetch missing and/or nested unregistered submodules
      previously_missing_set = set()
      while True:
        self._ReloadManifest(manifest_name)
        all_projects = self.GetProjects(args,
                                        missing_ok=True,
                                        submodules_ok=opt.fetch_submodules)
        missing = []
        for project in all_projects:
          if project.gitdir not in fetched:
            missing.append(project)
        if not missing:
          break
        # Stop us from non-stopped fetching actually-missing repos: If set of
        # missing repos has not been changed from last fetch, we break.
        missing_set = set(p.name for p in missing)
        if previously_missing_set == missing_set:
          break
        previously_missing_set = missing_set
        fetched.update(self._Fetch(missing, opt))

    if self.manifest.IsMirror or self.manifest.IsArchive:
      # bail out now, we have no working tree
      return

    if self.UpdateProjectList():
      sys.exit(1)

    syncbuf = SyncBuffer(mp.config,
                         detach_head = opt.detach_head)
    pm = Progress('Syncing work tree', len(all_projects))
    for project in all_projects:
      pm.update()
      if project.worktree:
        start = time.time()
        project.Sync_LocalHalf(syncbuf, force_sync=opt.force_sync)
        self.event_log.AddSync(project, event_log.TASK_SYNC_LOCAL,
                               start, time.time(), syncbuf.Recently())
    pm.end()
    print(file=sys.stderr)
    if not syncbuf.Finish():
      sys.exit(1)

    # If there's a notice that's supposed to print at the end of the sync, print
    # it now...
    if self.manifest.notice:
      print(self.manifest.notice)

def _PostRepoUpgrade(manifest, quiet=False):
  wrapper = Wrapper()
  if wrapper.NeedSetupGnuPG():
    wrapper.SetupGnuPG(quiet)
  for project in manifest.projects:
    if project.Exists:
      project.PostRepoUpgrade()

def _PostRepoFetch(rp, no_repo_verify=False, verbose=False):
  if rp.HasChanges:
    print('info: A new version of repo is available', file=sys.stderr)
    print(file=sys.stderr)
    if no_repo_verify or _VerifyTag(rp):
      syncbuf = SyncBuffer(rp.config)
      rp.Sync_LocalHalf(syncbuf)
      if not syncbuf.Finish():
        sys.exit(1)
      print('info: Restarting repo with latest version', file=sys.stderr)
      raise RepoChangedException(['--repo-upgraded'])
    else:
      print('warning: Skipped upgrade to unverified version', file=sys.stderr)
  else:
    if verbose:
      print('repo version %s is current' % rp.work_git.describe(HEAD),
            file=sys.stderr)

def _VerifyTag(project):
  gpg_dir = os.path.expanduser('~/.repoconfig/gnupg')
  if not os.path.exists(gpg_dir):
    print('warning: GnuPG was not available during last "repo init"\n'
          'warning: Cannot automatically authenticate repo."""',
          file=sys.stderr)
    return True

  try:
    cur = project.bare_git.describe(project.GetRevisionId())
  except GitError:
    cur = None

  if not cur \
     or re.compile(r'^.*-[0-9]{1,}-g[0-9a-f]{1,}$').match(cur):
    rev = project.revisionExpr
    if rev.startswith(R_HEADS):
      rev = rev[len(R_HEADS):]

    print(file=sys.stderr)
    print("warning: project '%s' branch '%s' is not signed"
          % (project.name, rev), file=sys.stderr)
    return False

  env = os.environ.copy()
  env['GIT_DIR'] = project.gitdir.encode()
  env['GNUPGHOME'] = gpg_dir.encode()

  cmd = [GIT, 'tag', '-v', cur]
  proc = subprocess.Popen(cmd,
                          stdout = subprocess.PIPE,
                          stderr = subprocess.PIPE,
                          env = env)
  out = proc.stdout.read()
  proc.stdout.close()

  err = proc.stderr.read()
  proc.stderr.close()

  if proc.wait() != 0:
    print(file=sys.stderr)
    print(out, file=sys.stderr)
    print(err, file=sys.stderr)
    print(file=sys.stderr)
    return False
  return True


class _FetchTimes(object):
  _ALPHA = 0.5

  def __init__(self, manifest):
    self._path = os.path.join(manifest.repodir, '.repo_fetchtimes.json')
    self._times = None
    self._seen = set()

  def Get(self, project):
    self._Load()
    return self._times.get(project.name, _ONE_DAY_S)

  def Set(self, project, t):
    self._Load()
    name = project.name
    old = self._times.get(name, t)
    self._seen.add(name)
    a = self._ALPHA
    self._times[name] = (a*t) + ((1-a) * old)

  def _Load(self):
    if self._times is None:
      try:
        f = open(self._path)
        try:
          self._times = json.load(f)
        finally:
          f.close()
      except (IOError, ValueError):
        try:
          os.remove(self._path)
        except OSError:
          pass
        self._times = {}

  def Save(self):
    if self._times is None:
      return

    to_delete = []
    for name in self._times:
      if name not in self._seen:
        to_delete.append(name)
    for name in to_delete:
      del self._times[name]

    try:
      f = open(self._path, 'w')
      try:
        json.dump(self._times, f, indent=2)
      finally:
        f.close()
    except (IOError, TypeError):
      try:
        os.remove(self._path)
      except OSError:
        pass

# This is a replacement for xmlrpc.client.Transport using urllib2
# and supporting persistent-http[s]. It cannot change hosts from
# request to request like the normal transport, the real url
# is passed during initialization.
class PersistentTransport(xmlrpc.client.Transport):
  def __init__(self, orig_host):
    self.orig_host = orig_host

  def request(self, host, handler, request_body, verbose=False):
    with GetUrlCookieFile(self.orig_host, not verbose) as (cookiefile, proxy):
      # Python doesn't understand cookies with the #HttpOnly_ prefix
      # Since we're only using them for HTTP, copy the file temporarily,
      # stripping those prefixes away.
      if cookiefile:
        tmpcookiefile = tempfile.NamedTemporaryFile()
        tmpcookiefile.write("# HTTP Cookie File")
        try:
          with open(cookiefile) as f:
            for line in f:
              if line.startswith("#HttpOnly_"):
                line = line[len("#HttpOnly_"):]
              tmpcookiefile.write(line)
          tmpcookiefile.flush()

          cookiejar = cookielib.MozillaCookieJar(tmpcookiefile.name)
          try:
            cookiejar.load()
          except cookielib.LoadError:
            cookiejar = cookielib.CookieJar()
        finally:
          tmpcookiefile.close()
      else:
        cookiejar = cookielib.CookieJar()

      proxyhandler = urllib.request.ProxyHandler
      if proxy:
        proxyhandler = urllib.request.ProxyHandler({
            "http": proxy,
            "https": proxy })

      opener = urllib.request.build_opener(
          urllib.request.HTTPCookieProcessor(cookiejar),
          proxyhandler)

      url = urllib.parse.urljoin(self.orig_host, handler)
      parse_results = urllib.parse.urlparse(url)

      scheme = parse_results.scheme
      if scheme == 'persistent-http':
        scheme = 'http'
      if scheme == 'persistent-https':
        # If we're proxying through persistent-https, use http. The
        # proxy itself will do the https.
        if proxy:
          scheme = 'http'
        else:
          scheme = 'https'

      # Parse out any authentication information using the base class
      host, extra_headers, _ = self.get_host_info(parse_results.netloc)

      url = urllib.parse.urlunparse((
          scheme,
          host,
          parse_results.path,
          parse_results.params,
          parse_results.query,
          parse_results.fragment))

      request = urllib.request.Request(url, request_body)
      if extra_headers is not None:
        for (name, header) in extra_headers:
          request.add_header(name, header)
      request.add_header('Content-Type', 'text/xml')
      try:
        response = opener.open(request)
      except urllib.error.HTTPError as e:
        if e.code == 501:
          # We may have been redirected through a login process
          # but our POST turned into a GET. Retry.
          response = opener.open(request)
        else:
          raise

      p, u = xmlrpc.client.getparser()
      while 1:
        data = response.read(1024)
        if not data:
          break
        p.feed(data)
      p.close()
      return u.close()

  def close(self):
    pass