fileformat = None

        revision = None

        ext = None

        subrepos = request.GET.get('subrepos') == 'true'

        for a_type, ext_data in settings.ARCHIVE_SPECS.items():

            archive_spec = fname.split(ext_data[1])

            if len(archive_spec) == 2 and archive_spec[1] == '':

                fileformat = a_type or ext_data[1]

                revision = archive_spec[0]

                ext = ext_data[1]

        try:

            dbrepo = RepoModel().get_by_repo_name(repo_name)

            if not dbrepo.enable_downloads:

                return _('Downloads disabled')

            if c.db_repo_scm_instance.alias == 'hg':

                # patch and reset hooks section of UI config to not run any

                # hooks on fetching archives with subrepos

                for k, v in c.db_repo_scm_instance._repo.ui.configitems('hooks'):

                    c.db_repo_scm_instance._repo.ui.setconfig('hooks', k, None)

            cs = c.db_repo_scm_instance.get_changeset(revision)

            content_type = settings.ARCHIVE_SPECS[fileformat][0]

        except ChangesetDoesNotExistError:

            return _('Unknown revision %s') % revision

        except EmptyRepositoryError:

            return _('Empty repository')

        except (ImproperArchiveTypeError, KeyError):

            return _('Unknown archive type')

        # archive cache

        from kallithea import CONFIG

        rev_name = cs.raw_id[:12]

        archive_name = '%s-%s%s' % (safe_str(repo_name.replace('/', '_')),

                                    safe_str(rev_name), ext)

        use_cached_archive = False  # defines if we use cached version of archive

        archive_cache_enabled = CONFIG.get('archive_cache_dir')

        if not subrepos and archive_cache_enabled:

            #check if we it's ok to write

            if not os.path.isdir(CONFIG['archive_cache_dir']):

                os.makedirs(CONFIG['archive_cache_dir'])

            cached_archive_path = os.path.join(CONFIG['archive_cache_dir'], archive_name)

            if os.path.isfile(cached_archive_path):

                log.debug('Found cached archive in %s' % cached_archive_path)

                fd, archive = None, cached_archive_path

                use_cached_archive = True

            else:

                log.debug('Archive %s is not yet cached' % (archive_name))

        if not use_cached_archive:

            # generate new archive

            temp_stream = None

            try:

                fd, archive = tempfile.mkstemp()

                temp_stream = open(archive, 'wb')

                log.debug('Creating new temp archive in %s' % archive)

                cs.fill_archive(stream=temp_stream, kind=fileformat, subrepos=subrepos)

                if not subrepos and archive_cache_enabled:

                    #if we generated the archive and use cache rename that

                    log.debug('Storing new archive in %s' % cached_archive_path)

                    shutil.move(archive, cached_archive_path)

                    archive = cached_archive_path

            finally:

                if temp_stream:

                    temp_stream.close()

        def get_chunked_archive(archive):

            stream = open(archive, 'rb')

            while True:

                data = stream.read(16 * 1024)

                if not data:

                    stream.close()

                    if fd:  # fd means we used temporary file

                        os.close(fd)

                    if not archive_cache_enabled:

                        log.debug('Destroing temp archive %s' % archive)

                        os.remove(archive)

                    break

                yield data

        # store download action

        action_logger(user=c.authuser,

                      action='user_downloaded_archive:%s' % (archive_name),

                      repo=repo_name, ipaddr=self.ip_addr, commit=True)

        response.content_disposition = str('attachment; filename=%s' % (archive_name))

        response.content_type = str(content_type)

        return get_chunked_archive(archive)

    @LoginRequired()

    @HasRepoPermissionAnyDecorator('repository.read', 'repository.write',

                                   'repository.admin')

    def diff(self, repo_name, f_path):

        ignore_whitespace = request.GET.get('ignorews') == '1'

        line_context = request.GET.get('context', 3)

        diff2 = request.GET.get('diff2', '')

        c.action = request.GET.get('diff')

        c.no_changes = diff1 == diff2

        c.f_path = f_path

        c.big_diff = False

        c.anchor_url = anchor_url

        c.ignorews_url = _ignorews_url

        c.context_url = _context_url

        c.changes = OrderedDict()

        c.changes[diff2] = []

        #special case if we want a show rev only, it's impl here

        #to reduce JS and callbacks

        if request.GET.get('show_rev'):

            if str2bool(request.GET.get('annotate', 'False')):

                _url = url('files_annotate_home', repo_name=c.repo_name,

                           revision=diff1, f_path=c.f_path)

            else:

                _url = url('files_home', repo_name=c.repo_name,

                           revision=diff1, f_path=c.f_path)

            return redirect(_url)

        try:

            if diff1 not in ['', None, 'None', '0' * 12, '0' * 40]:

                c.changeset_1 = c.db_repo_scm_instance.get_changeset(diff1)

                try:

                    node1 = c.changeset_1.get_node(f_path)

                    if node1.is_dir():

                        raise NodeError('%s path is a %s not a file'

                                        % (node1, type(node1)))

                except NodeDoesNotExistError:

                    c.changeset_1 = EmptyChangeset(cs=diff1,

                                                   revision=c.changeset_1.revision,

                                                   repo=c.db_repo_scm_instance)

                    node1 = FileNode(f_path, '', changeset=c.changeset_1)

            else:

                c.changeset_1 = EmptyChangeset(repo=c.db_repo_scm_instance)

                node1 = FileNode(f_path, '', changeset=c.changeset_1)

            if diff2 not in ['', None, 'None', '0' * 12, '0' * 40]:

                c.changeset_2 = c.db_repo_scm_instance.get_changeset(diff2)

                try:

                    node2 = c.changeset_2.get_node(f_path)

                    if node2.is_dir():

                        raise NodeError('%s path is a %s not a file'

                                        % (node2, type(node2)))

                except NodeDoesNotExistError:

                    c.changeset_2 = EmptyChangeset(cs=diff2,

                                                   revision=c.changeset_2.revision,

                                                   repo=c.db_repo_scm_instance)

                    node2 = FileNode(f_path, '', changeset=c.changeset_2)

            else:

                c.changeset_2 = EmptyChangeset(repo=c.db_repo_scm_instance)

                node2 = FileNode(f_path, '', changeset=c.changeset_2)

        except (RepositoryError, NodeError):

            log.error(traceback.format_exc())

            return redirect(url('files_home', repo_name=c.repo_name,

                                f_path=f_path))

        if c.action == 'download':

            _diff = diffs.get_gitdiff(node1, node2,

                                      ignore_whitespace=ignore_whitespace,

                                      context=line_context)

            diff = diffs.DiffProcessor(_diff, format='gitdiff')

            diff_name = '%s_vs_%s.diff' % (diff1, diff2)

            response.content_type = 'text/plain'

            response.content_disposition = (

                'attachment; filename=%s' % diff_name

            )

            return diff.as_raw()

        elif c.action == 'raw':

            _diff = diffs.get_gitdiff(node1, node2,

                                      ignore_whitespace=ignore_whitespace,

                                      context=line_context)

            diff = diffs.DiffProcessor(_diff, format='gitdiff')

            response.content_type = 'text/plain'

            return diff.as_raw()

        else:

            fid = h.FID(diff2, node2.path)

            line_context_lcl = get_line_ctx(fid, request.GET)

            ign_whitespace_lcl = get_ignore_ws(fid, request.GET)

            lim = request.GET.get('fulldiff') or self.cut_off_limit

            _, cs1, cs2, diff, st = diffs.wrapped_diff(filenode_old=node1,

                                         filenode_new=node2,

                                         cut_off_limit=lim,

                                         ignore_whitespace=ign_whitespace_lcl,

                                         line_context=line_context_lcl,

                                         enable_comments=False)

            op = ''

            filename = node1.path

            cs_changes = {

                'fid': [cs1, cs2, op, filename, diff, st]