# blows up if you sprinkle "flush" (0000) as "0001\n".

        # It reads binary, per number of bytes specified.

        # if you do add '\n' as part of data, count it.

        smart_server_advert = '# service=%s' % git_command

        try:

            out = subprocessio.SubprocessIOChunker(

                r'git %s --stateless-rpc --advertise-refs "%s"' % (

                                git_command[4:], self.content_path),

                starting_values=[

                    str(hex(len(smart_server_advert) + 4)[2:]

                        .rjust(4, '0') + smart_server_advert + '0000')

                ]

            )

        except EnvironmentError, e:

            log.exception(e)

            raise exc.HTTPExpectationFailed()

        resp = Response()

        resp.content_type = 'application/x-%s-advertisement' % str(git_command)

        resp.app_iter = out

        return resp

    def backend(self, request, environ):

        """

        WSGI Response producer for HTTP POST Git Smart HTTP requests.

        Reads commands and data from HTTP POST's body.

        returns an iterator obj with contents of git command's

        response to stdout

        """

        git_command = self._get_fixedpath(request.path_info)

        if git_command not in self.commands:

            log.debug('command %s not allowed' % git_command)

            return exc.HTTPMethodNotAllowed()

        if 'CONTENT_LENGTH' in environ:

            inputstream = FileWrapper(environ['wsgi.input'],

                                      request.content_length)

        else:

            inputstream = environ['wsgi.input']

        try:

            out = subprocessio.SubprocessIOChunker(

                r'git %s --stateless-rpc "%s"' % (git_command[4:],

                                                  self.content_path),

                inputstream=inputstream

                )

        except EnvironmentError, e:

            log.exception(e)

            raise exc.HTTPExpectationFailed()

        if git_command in [u'git-receive-pack']:

            # updating refs manually after each push.

            # Needed for pre-1.7.0.4 git clients using regular HTTP mode.

            subprocess.call(u'git --git-dir "%s" '

                            'update-server-info' % self.content_path,

                            shell=True)

        resp = Response()

        resp.content_type = 'application/x-%s-result' % git_command.encode('utf8')

        resp.app_iter = out

        return resp

    def __call__(self, environ, start_response):

        request = Request(environ)

        _path = self._get_fixedpath(request.path_info)

        if _path.startswith('info/refs'):

            app = self.inforefs

        elif [a for a in self.valid_accepts if a in request.accept]:

            app = self.backend

        try:

            resp = app(request, environ)

        except exc.HTTPException, e:

            resp = e

            log.exception(e)

        except Exception, e:

            log.exception(e)

            resp = exc.HTTPInternalServerError()

        return resp(environ, start_response)

class GitDirectory(object):

    def __init__(self, repo_root, repo_name):

        repo_location = os.path.join(repo_root, repo_name)

        if not os.path.isdir(repo_location):

            raise OSError(repo_location)

        self.content_path = repo_location

        self.repo_name = repo_name

        self.repo_location = repo_location

    def __call__(self, environ, start_response):

        content_path = self.content_path

        try:

            app = GitRepository(self.repo_name, content_path)

        except (AssertionError, OSError):

            if os.path.isdir(os.path.join(content_path, '.git')):

            else:

                return exc.HTTPNotFound()(environ, start_response)

        return app(environ, start_response)

def make_wsgi_app(repo_name, repo_root):

    return GitDirectory(repo_root, repo_name)