Implemented pull command for remote repos for git

- added mimic ui objects into GitRepos to better handle hooks logic

rhodecode/lib/middleware/simplegit.py

@@ -1,286 +1,300 b''
 # -*- coding: utf-8 -*-
 """
     rhodecode.lib.middleware.simplegit
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
     SimpleGit middleware for handling git protocol request (push/clone etc.)
     It's implemented with basic auth function
 
     :created_on: Apr 28, 2010
     :author: marcink
     :copyright: (C) 2010-2012 Marcin Kuzminski <[e-mail]>
     :license: GPLv3, see COPYING for more details.
 """
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation, either version 3 of the License, or
 # (at your option) any later version.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
 import re
 import logging
 import traceback
 
 from dulwich import server as dulserver
 
 
 class SimpleGitUploadPackHandler(dulserver.UploadPackHandler):
 
     def handle(self):
         write = lambda x: self.proto.write_sideband(1, x)
 
         graph_walker = dulserver.ProtocolGraphWalker(self,
                                                      self.repo.object_store,
                                                      self.repo.get_peeled)
         objects_iter = self.repo.fetch_objects(
           graph_walker.determine_wants, graph_walker, self.progress,
           get_tagged=self.get_tagged)
 
         # Did the process short-circuit (e.g. in a stateless RPC call)? Note
         # that the client still expects a 0-object pack in most cases.
         if objects_iter is None:
             return
 
         self.progress("counting objects: %d, done.\n" % len(objects_iter))
         dulserver.write_pack_objects(dulserver.ProtocolFile(None, write),
                                      objects_iter)
         messages = []
         messages.append('thank you for using rhodecode')
 
         for msg in messages:
             self.progress(msg + "\n")
         # we are done
         self.proto.write("0000")
 
 
 dulserver.DEFAULT_HANDLERS = {
   'git-upload-pack': SimpleGitUploadPackHandler,
   'git-receive-pack': dulserver.ReceivePackHandler,
 }
 
 from dulwich.repo import Repo
 from dulwich.web import make_wsgi_chain
 
 from paste.httpheaders import REMOTE_USER, AUTH_TYPE
 
 from rhodecode.lib.utils2 import safe_str
 from rhodecode.lib.base import BaseVCSController
 from rhodecode.lib.auth import get_container_username
 from rhodecode.lib.utils import is_valid_repo, make_ui
 from rhodecode.model.db import User
 
 from webob.exc import HTTPNotFound, HTTPForbidden, HTTPInternalServerError
 
 log = logging.getLogger(__name__)
 
 
 GIT_PROTO_PAT = re.compile(r'^/(.+)/(info/refs|git-upload-pack|git-receive-pack)')
 
 
 def is_git(environ):
     path_info = environ['PATH_INFO']
     isgit_path = GIT_PROTO_PAT.match(path_info)
     log.debug('pathinfo: %s detected as GIT %s' % (
         path_info, isgit_path != None)
     )
     return isgit_path
 
 
 class SimpleGit(BaseVCSController):
 
     def _handle_request(self, environ, start_response):
 
         if not is_git(environ):
             return self.application(environ, start_response)
 
         ipaddr = self._get_ip_addr(environ)
         username = None
         self._git_first_op = False
         # skip passing error to error controller
         environ['pylons.status_code_redirect'] = True
 
         #======================================================================
         # EXTRACT REPOSITORY NAME FROM ENV
         #======================================================================
         try:
             repo_name = self.__get_repository(environ)
             log.debug('Extracted repo name is %s' % repo_name)
         except:
             return HTTPInternalServerError()(environ, start_response)
 
         # quick check if that dir exists...
         if is_valid_repo(repo_name, self.basepath) is False:
             return HTTPNotFound()(environ, start_response)
 
         #======================================================================
         # GET ACTION PULL or PUSH
         #======================================================================
         action = self.__get_action(environ)
 
         #======================================================================
         # CHECK ANONYMOUS PERMISSION
         #======================================================================
         if action in ['pull', 'push']:
             anonymous_user = self.__get_user('default')
             username = anonymous_user.username
             anonymous_perm = self._check_permission(action, anonymous_user,
                                                     repo_name)
 
             if anonymous_perm is not True or anonymous_user.active is False:
                 if anonymous_perm is not True:
                     log.debug('Not enough credentials to access this '
                               'repository as anonymous user')
                 if anonymous_user.active is False:
                     log.debug('Anonymous access is disabled, running '
                               'authentication')
                 #==============================================================
                 # DEFAULT PERM FAILED OR ANONYMOUS ACCESS IS DISABLED SO WE
                 # NEED TO AUTHENTICATE AND ASK FOR AUTH USER PERMISSIONS
                 #==============================================================
 
                 # Attempting to retrieve username from the container
                 username = get_container_username(environ, self.config)
 
                 # If not authenticated by the container, running basic auth
                 if not username:
                     self.authenticate.realm = \
                         safe_str(self.config['rhodecode_realm'])
                     result = self.authenticate(environ)
                     if isinstance(result, str):
                         AUTH_TYPE.update(environ, 'basic')
                         REMOTE_USER.update(environ, result)
                         username = result
                     else:
                         return result.wsgi_application(environ, start_response)
 
                 #==============================================================
                 # CHECK PERMISSIONS FOR THIS REQUEST USING GIVEN USERNAME
                 #==============================================================
                 if action in ['pull', 'push']:
                     try:
                         user = self.__get_user(username)
                         if user is None or not user.active:
                             return HTTPForbidden()(environ, start_response)
                         username = user.username
                     except:
                         log.error(traceback.format_exc())
                         return HTTPInternalServerError()(environ,
                                                          start_response)
 
                     #check permissions for this repository
                     perm = self._check_permission(action, user, repo_name)
                     if perm is not True:
                         return HTTPForbidden()(environ, start_response)
         extras = {
             'ip': ipaddr,
             'username': username,
             'action': action,
             'repository': repo_name,
             'scm': 'git',
         }
 
         #===================================================================
         # GIT REQUEST HANDLING
         #===================================================================
         repo_path = os.path.join(safe_str(self.basepath), safe_str(repo_name))
         log.debug('Repository path is %s' % repo_path)
 
         baseui = make_ui('db')
-        for k, v in extras.items():
-            baseui.setconfig('rhodecode_extras', k, v)
+        self.__inject_extras(repo_path, baseui, extras)
+
 
         try:
             # invalidate cache on push
             if action == 'push':
                 self._invalidate_cache(repo_name)
             self._handle_githooks(action, baseui, environ)
 
             log.info('%s action on GIT repo "%s"' % (action, repo_name))
             app = self.__make_app(repo_name, repo_path)
             return app(environ, start_response)
         except Exception:
             log.error(traceback.format_exc())
             return HTTPInternalServerError()(environ, start_response)
 
     def __make_app(self, repo_name, repo_path):
         """
         Make an wsgi application using dulserver
 
         :param repo_name: name of the repository
         :param repo_path: full path to the repository
         """
         _d = {'/' + repo_name: Repo(repo_path)}
         backend = dulserver.DictBackend(_d)
         gitserve = make_wsgi_chain(backend)
 
         return gitserve
 
     def __get_repository(self, environ):
         """
         Get's repository name out of PATH_INFO header
 
         :param environ: environ where PATH_INFO is stored
         """
         try:
             environ['PATH_INFO'] = self._get_by_id(environ['PATH_INFO'])
             repo_name = GIT_PROTO_PAT.match(environ['PATH_INFO']).group(1)
         except:
             log.error(traceback.format_exc())
             raise
 
         return repo_name
 
     def __get_user(self, username):
         return User.get_by_username(username)
 
     def __get_action(self, environ):
         """
         Maps git request commands into a pull or push command.
 
         :param environ:
         """
         service = environ['QUERY_STRING'].split('=')
 
         if len(service) > 1:
             service_cmd = service[1]
             mapping = {
                 'git-receive-pack': 'push',
                 'git-upload-pack': 'pull',
             }
             op = mapping[service_cmd]
             self._git_stored_op = op
             return op
         else:
             # try to fallback to stored variable as we don't know if the last
             # operation is pull/push
             op = getattr(self, '_git_stored_op', 'pull')
         return op
 
     def _handle_githooks(self, action, baseui, environ):
-
         from rhodecode.lib.hooks import log_pull_action, log_push_action
         service = environ['QUERY_STRING'].split('=')
         if len(service) < 2:
             return
 
-        class cont(object):
-            pass
-
-        repo = cont()
-        setattr(repo, 'ui', baseui)
+        from rhodecode.model.db import Repository
+        _repo = Repository.get_by_repo_name(repo_name)
+        _repo = _repo.scm_instance
+        _repo._repo.ui = baseui
 
         push_hook = 'pretxnchangegroup.push_logger'
         pull_hook = 'preoutgoing.pull_logger'
         _hooks = dict(baseui.configitems('hooks')) or {}
         if action == 'push' and _hooks.get(push_hook):
-            log_push_action(ui=baseui, repo=repo)
+            log_push_action(ui=baseui, repo=repo._repo)
         elif action == 'pull' and _hooks.get(pull_hook):
-            log_pull_action(ui=baseui, repo=repo)
+            log_pull_action(ui=baseui, repo=repo._repo)
+
+    def __inject_extras(self, repo_path, baseui, extras={}):
+        """
+        Injects some extra params into baseui instance
+
+        :param baseui: baseui instance
+        :param extras: dict with extra params to put into baseui
+        """
+
+        # make our hgweb quiet so it doesn't print output
+        baseui.setconfig('ui', 'quiet', 'true')
+
+        #inject some additional parameters that will be available in ui
+        #for hooks
+        for k, v in extras.items():
+            baseui.setconfig('rhodecode_extras', k, v)

rhodecode/lib/vcs/backends/git/repository.py

@@ -1,525 +1,545 b''
 # -*- coding: utf-8 -*-
 """
     vcs.backends.git
     ~~~~~~~~~~~~~~~~
 
     Git backend implementation.
 
     :created_on: Apr 8, 2010
     :copyright: (c) 2010-2011 by Marcin Kuzminski, Lukasz Balcerzak.
 """
 
 import os
 import re
 import time
 import posixpath
 from dulwich.repo import Repo, NotGitRepository
 #from dulwich.config import ConfigFile
 from string import Template
 from subprocess import Popen, PIPE
 from rhodecode.lib.vcs.backends.base import BaseRepository
 from rhodecode.lib.vcs.exceptions import BranchDoesNotExistError
 from rhodecode.lib.vcs.exceptions import ChangesetDoesNotExistError
 from rhodecode.lib.vcs.exceptions import EmptyRepositoryError
 from rhodecode.lib.vcs.exceptions import RepositoryError
 from rhodecode.lib.vcs.exceptions import TagAlreadyExistError
 from rhodecode.lib.vcs.exceptions import TagDoesNotExistError
 from rhodecode.lib.vcs.utils import safe_unicode, makedate, date_fromtimestamp
 from rhodecode.lib.vcs.utils.lazy import LazyProperty
 from rhodecode.lib.vcs.utils.ordered_dict import OrderedDict
 from rhodecode.lib.vcs.utils.paths import abspath
 from rhodecode.lib.vcs.utils.paths import get_user_home
 from .workdir import GitWorkdir
 from .changeset import GitChangeset
 from .inmemory import GitInMemoryChangeset
 from .config import ConfigFile
 
 
 class GitRepository(BaseRepository):
     """
     Git repository backend.
     """
     DEFAULT_BRANCH_NAME = 'master'
     scm = 'git'
 
     def __init__(self, repo_path, create=False, src_url=None,
                  update_after_clone=False, bare=False):
 
         self.path = abspath(repo_path)
         self._repo = self._get_repo(create, src_url, update_after_clone, bare)
+        #temporary set that to now at later we will move it to constructor
+        baseui = None
+        if baseui is None:
+            from mercurial.ui import ui
+            baseui = ui()
+        # patch the instance of GitRepo with an "FAKE" ui object to add 
+        # compatibility layer with Mercurial
+        setattr(self._repo, 'ui', baseui)
+
         try:
             self.head = self._repo.head()
         except KeyError:
             self.head = None
 
         self._config_files = [
             bare and abspath(self.path, 'config') or abspath(self.path, '.git',
                 'config'),
             abspath(get_user_home(), '.gitconfig'),
         ]
 
     @LazyProperty
     def revisions(self):
         """
         Returns list of revisions' ids, in ascending order.  Being lazy
         attribute allows external tools to inject shas from cache.
         """
         return self._get_all_revisions()
 
     def run_git_command(self, cmd):
         """
         Runs given ``cmd`` as git command and returns tuple
         (returncode, stdout, stderr).
 
         .. note::
            This method exists only until log/blame functionality is implemented
            at Dulwich (see https://bugs.launchpad.net/bugs/645142). Parsing
            os command's output is road to hell...
 
         :param cmd: git command to be executed
         """
 
         _copts = ['-c', 'core.quotepath=false', ]
         _str_cmd = False
         if isinstance(cmd, basestring):
             cmd = [cmd]
             _str_cmd = True
 
         cmd = ['GIT_CONFIG_NOGLOBAL=1', 'git'] + _copts + cmd
         if _str_cmd:
             cmd = ' '.join(cmd)
         try:
             opts = dict(
                 shell=isinstance(cmd, basestring),
                 stdout=PIPE,
                 stderr=PIPE)
             if os.path.isdir(self.path):
                 opts['cwd'] = self.path
             p = Popen(cmd, **opts)
         except OSError, err:
             raise RepositoryError("Couldn't run git command (%s).\n"
                 "Original error was:%s" % (cmd, err))
         so, se = p.communicate()
         if not se.startswith("fatal: bad default revision 'HEAD'") and \
             p.returncode != 0:
             raise RepositoryError("Couldn't run git command (%s).\n"
                 "stderr:\n%s" % (cmd, se))
         return so, se
 
     def _check_url(self, url):
         """
         Functon will check given url and try to verify if it's a valid
         link. Sometimes it may happened that mercurial will issue basic
         auth request that can cause whole API to hang when used from python
         or other external calls.
 
         On failures it'll raise urllib2.HTTPError
         """
 
         #TODO: implement this
         pass
 
     def _get_repo(self, create, src_url=None, update_after_clone=False,
             bare=False):
         if create and os.path.exists(self.path):
             raise RepositoryError("Location already exist")
         if src_url and not create:
             raise RepositoryError("Create should be set to True if src_url is "
                                   "given (clone operation creates repository)")
         try:
             if create and src_url:
                 self._check_url(src_url)
                 self.clone(src_url, update_after_clone, bare)
                 return Repo(self.path)
             elif create:
                 os.mkdir(self.path)
                 if bare:
                     return Repo.init_bare(self.path)
                 else:
                     return Repo.init(self.path)
             else:
                 return Repo(self.path)
         except (NotGitRepository, OSError), err:
             raise RepositoryError(err)
 
     def _get_all_revisions(self):
         cmd = 'rev-list --all --date-order'
         try:
             so, se = self.run_git_command(cmd)
         except RepositoryError:
             # Can be raised for empty repositories
             return []
         revisions = so.splitlines()
         revisions.reverse()
         return revisions
 
     def _get_revision(self, revision):
         """
         For git backend we always return integer here. This way we ensure
         that changset's revision attribute would become integer.
         """
         pattern = re.compile(r'^[[0-9a-fA-F]{12}|[0-9a-fA-F]{40}]$')
         is_bstr = lambda o: isinstance(o, (str, unicode))
         is_null = lambda o: len(o) == revision.count('0')
 
         if len(self.revisions) == 0:
             raise EmptyRepositoryError("There are no changesets yet")
 
         if revision in (None, '', 'tip', 'HEAD', 'head', -1):
             revision = self.revisions[-1]
 
         if ((is_bstr(revision) and revision.isdigit() and len(revision) < 12)
             or isinstance(revision, int) or is_null(revision)):
             try:
                 revision = self.revisions[int(revision)]
             except:
                 raise ChangesetDoesNotExistError("Revision %r does not exist "
                     "for this repository %s" % (revision, self))
 
         elif is_bstr(revision):
             if not pattern.match(revision) or revision not in self.revisions:
                 raise ChangesetDoesNotExistError("Revision %r does not exist "
                     "for this repository %s" % (revision, self))
 
         # Ensure we return full id
         if not pattern.match(str(revision)):
             raise ChangesetDoesNotExistError("Given revision %r not recognized"
                 % revision)
         return revision
 
     def _get_archives(self, archive_name='tip'):
 
         for i in [('zip', '.zip'), ('gz', '.tar.gz'), ('bz2', '.tar.bz2')]:
                 yield {"type": i[0], "extension": i[1], "node": archive_name}
 
     def _get_url(self, url):
         """
         Returns normalized url. If schema is not given, would fall to
         filesystem (``file:///``) schema.
         """
         url = str(url)
         if url != 'default' and not '://' in url:
             url = ':///'.join(('file', url))
         return url
 
     @LazyProperty
     def name(self):
         return os.path.basename(self.path)
 
     @LazyProperty
     def last_change(self):
         """
         Returns last change made on this repository as datetime object
         """
         return date_fromtimestamp(self._get_mtime(), makedate()[1])
 
     def _get_mtime(self):
         try:
             return time.mktime(self.get_changeset().date.timetuple())
         except RepositoryError:
             # fallback to filesystem
             in_path = os.path.join(self.path, '.git', "index")
             he_path = os.path.join(self.path, '.git', "HEAD")
             if os.path.exists(in_path):
                 return os.stat(in_path).st_mtime
             else:
                 return os.stat(he_path).st_mtime
 
     @LazyProperty
     def description(self):
         undefined_description = u'unknown'
         description_path = os.path.join(self.path, '.git', 'description')
         if os.path.isfile(description_path):
             return safe_unicode(open(description_path).read())
         else:
             return undefined_description
 
     @LazyProperty
     def contact(self):
         undefined_contact = u'Unknown'
         return undefined_contact
 
     @property
     def branches(self):
         if not self.revisions:
             return {}
         refs = self._repo.refs.as_dict()
         sortkey = lambda ctx: ctx[0]
         _branches = [('/'.join(ref.split('/')[2:]), head)
             for ref, head in refs.items()
             if ref.startswith('refs/heads/') and not ref.endswith('/HEAD')]
         return OrderedDict(sorted(_branches, key=sortkey, reverse=False))
 
     def _heads(self, reverse=False):
         refs = self._repo.get_refs()
         heads = {}
 
         for key, val in refs.items():
             for ref_key in ['refs/heads/', 'refs/remotes/origin/']:
                 if key.startswith(ref_key):
                     n = key[len(ref_key):]
                     if n not in ['HEAD']:
                         heads[n] = val
 
         return heads if reverse else dict((y,x) for x,y in heads.iteritems())
 
     def _get_tags(self):
         if not self.revisions:
             return {}
         sortkey = lambda ctx: ctx[0]
         _tags = [('/'.join(ref.split('/')[2:]), head) for ref, head in
             self._repo.get_refs().items() if ref.startswith('refs/tags/')]
         return OrderedDict(sorted(_tags, key=sortkey, reverse=True))
 
     @LazyProperty
     def tags(self):
         return self._get_tags()
 
     def tag(self, name, user, revision=None, message=None, date=None,
             **kwargs):
         """
         Creates and returns a tag for the given ``revision``.
 
         :param name: name for new tag
         :param user: full username, i.e.: "Joe Doe <[e-mail]>"
         :param revision: changeset id for which new tag would be created
         :param message: message of the tag's commit
         :param date: date of tag's commit
 
         :raises TagAlreadyExistError: if tag with same name already exists
         """
         if name in self.tags:
             raise TagAlreadyExistError("Tag %s already exists" % name)
         changeset = self.get_changeset(revision)
         message = message or "Added tag %s for commit %s" % (name,
             changeset.raw_id)
         self._repo.refs["refs/tags/%s" % name] = changeset._commit.id
 
         self.tags = self._get_tags()
         return changeset
 
     def remove_tag(self, name, user, message=None, date=None):
         """
         Removes tag with the given ``name``.
 
         :param name: name of the tag to be removed
         :param user: full username, i.e.: "Joe Doe <[e-mail]>"
         :param message: message of the tag's removal commit
         :param date: date of tag's removal commit
 
         :raises TagDoesNotExistError: if tag with given name does not exists
         """
         if name not in self.tags:
             raise TagDoesNotExistError("Tag %s does not exist" % name)
         tagpath = posixpath.join(self._repo.refs.path, 'refs', 'tags', name)
         try:
             os.remove(tagpath)
             self.tags = self._get_tags()
         except OSError, e:
             raise RepositoryError(e.strerror)
 
     def get_changeset(self, revision=None):
         """
         Returns ``GitChangeset`` object representing commit from git repository
         at the given revision or head (most recent commit) if None given.
         """
         if isinstance(revision, GitChangeset):
             return revision
         revision = self._get_revision(revision)
         changeset = GitChangeset(repository=self, revision=revision)
         return changeset
 
     def get_changesets(self, start=None, end=None, start_date=None,
            end_date=None, branch_name=None, reverse=False):
         """
         Returns iterator of ``GitChangeset`` objects from start to end (both
         are inclusive), in ascending date order (unless ``reverse`` is set).
 
         :param start: changeset ID, as str; first returned changeset
         :param end: changeset ID, as str; last returned changeset
         :param start_date: if specified, changesets with commit date less than
           ``start_date`` would be filtered out from returned set
         :param end_date: if specified, changesets with commit date greater than
           ``end_date`` would be filtered out from returned set
         :param branch_name: if specified, changesets not reachable from given
           branch would be filtered out from returned set
         :param reverse: if ``True``, returned generator would be reversed
           (meaning that returned changesets would have descending date order)
 
         :raise BranchDoesNotExistError: If given ``branch_name`` does not
             exist.
         :raise ChangesetDoesNotExistError: If changeset for given ``start`` or
           ``end`` could not be found.
 
         """
         if branch_name and branch_name not in self.branches:
             raise BranchDoesNotExistError("Branch '%s' not found" \
                                           % branch_name)
         # %H at format means (full) commit hash, initial hashes are retrieved
         # in ascending date order
         cmd_template = 'log --date-order --reverse --pretty=format:"%H"'
         cmd_params = {}
         if start_date:
             cmd_template += ' --since "$since"'
             cmd_params['since'] = start_date.strftime('%m/%d/%y %H:%M:%S')
         if end_date:
             cmd_template += ' --until "$until"'
             cmd_params['until'] = end_date.strftime('%m/%d/%y %H:%M:%S')
         if branch_name:
             cmd_template += ' $branch_name'
             cmd_params['branch_name'] = branch_name
         else:
             cmd_template += ' --all'
 
         cmd = Template(cmd_template).safe_substitute(**cmd_params)
         revs = self.run_git_command(cmd)[0].splitlines()
         start_pos = 0
         end_pos = len(revs)
         if start:
             _start = self._get_revision(start)
             try:
                 start_pos = revs.index(_start)
             except ValueError:
                 pass
 
         if end is not None:
             _end = self._get_revision(end)
             try:
                 end_pos = revs.index(_end)
             except ValueError:
                 pass
 
         if None not in [start, end] and start_pos > end_pos:
             raise RepositoryError('start cannot be after end')
 
         if end_pos is not None:
             end_pos += 1
 
         revs = revs[start_pos:end_pos]
         if reverse:
             revs = reversed(revs)
         for rev in revs:
             yield self.get_changeset(rev)
 
     def get_diff(self, rev1, rev2, path=None, ignore_whitespace=False,
             context=3):
         """
         Returns (git like) *diff*, as plain text. Shows changes introduced by
         ``rev2`` since ``rev1``.
 
         :param rev1: Entry point from which diff is shown. Can be
           ``self.EMPTY_CHANGESET`` - in this case, patch showing all
           the changes since empty state of the repository until ``rev2``
         :param rev2: Until which revision changes should be shown.
         :param ignore_whitespace: If set to ``True``, would not show whitespace
           changes. Defaults to ``False``.
         :param context: How many lines before/after changed lines should be
           shown. Defaults to ``3``.
         """
         flags = ['-U%s' % context]
         if ignore_whitespace:
             flags.append('-w')
 
         if rev1 == self.EMPTY_CHANGESET:
             rev2 = self.get_changeset(rev2).raw_id
             cmd = ' '.join(['show'] + flags + [rev2])
         else:
             rev1 = self.get_changeset(rev1).raw_id
             rev2 = self.get_changeset(rev2).raw_id
             cmd = ' '.join(['diff'] + flags + [rev1, rev2])
 
         if path:
             cmd += ' -- "%s"' % path
         stdout, stderr = self.run_git_command(cmd)
         # If we used 'show' command, strip first few lines (until actual diff
         # starts)
         if rev1 == self.EMPTY_CHANGESET:
             lines = stdout.splitlines()
             x = 0
             for line in lines:
                 if line.startswith('diff'):
                     break
                 x += 1
             # Append new line just like 'diff' command do
             stdout = '\n'.join(lines[x:]) + '\n'
         return stdout
 
     @LazyProperty
     def in_memory_changeset(self):
         """
         Returns ``GitInMemoryChangeset`` object for this repository.
         """
         return GitInMemoryChangeset(self)
 
     def clone(self, url, update_after_clone=True, bare=False):
         """
         Tries to clone changes from external location.
 
         :param update_after_clone: If set to ``False``, git won't checkout
           working directory
         :param bare: If set to ``True``, repository would be cloned into
           *bare* git repository (no working directory at all).
         """
         url = self._get_url(url)
         cmd = ['clone']
         if bare:
             cmd.append('--bare')
         elif not update_after_clone:
             cmd.append('--no-checkout')
         cmd += ['--', '"%s"' % url, '"%s"' % self.path]
         cmd = ' '.join(cmd)
         # If error occurs run_git_command raises RepositoryError already
         self.run_git_command(cmd)
 
+    def pull(self, url):
+        """
+        Tries to pull changes from external location.
+        """
+        url = self._get_url(url)
+        cmd = ['pull']
+        cmd.append("--ff-only")
+        cmd = ' '.join(cmd)
+        # If error occurs run_git_command raises RepositoryError already
+        self.run_git_command(cmd)
+
     @LazyProperty
     def workdir(self):
         """
         Returns ``Workdir`` instance for this repository.
         """
         return GitWorkdir(self)
 
     def get_config_value(self, section, name, config_file=None):
         """
         Returns configuration value for a given [``section``] and ``name``.
 
         :param section: Section we want to retrieve value from
         :param name: Name of configuration we want to retrieve
         :param config_file: A path to file which should be used to retrieve
           configuration from (might also be a list of file paths)
         """
         if config_file is None:
             config_file = []
         elif isinstance(config_file, basestring):
             config_file = [config_file]
 
         def gen_configs():
             for path in config_file + self._config_files:
                 try:
                     yield ConfigFile.from_path(path)
                 except (IOError, OSError, ValueError):
                     continue
 
         for config in gen_configs():
             try:
                 return config.get(section, name)
             except KeyError:
                 continue
         return None
 
     def get_user_name(self, config_file=None):
         """
         Returns user's name from global configuration file.
 
         :param config_file: A path to file which should be used to retrieve
           configuration from (might also be a list of file paths)
         """
         return self.get_config_value('user', 'name', config_file)
 
     def get_user_email(self, config_file=None):
         """
         Returns user's email from global configuration file.
 
         :param config_file: A path to file which should be used to retrieve
           configuration from (might also be a list of file paths)
         """
         return self.get_config_value('user', 'email', config_file)