Method git_read_file

modules/handler.py:711–780

Read the content of the file from specific commit. This method uses `git cat-files` to read the file content from git index to enable support of smudge filters (fixes Issue #74). Git applies smudge filters to some commands like `archive`, `diff`, `checkout` and `cat-

(self, commit)

        ])

    def git_read_file(self, commit):
        """Read the content of the file from specific commit.

        This method uses `git cat-files` to read the file content from git
        index to enable support of smudge filters (fixes Issue #74). Git
        applies smudge filters to some commands like `archive`, `diff`,
        `checkout` and `cat-file` only, but not to commands like `show`.

        Arguments:
            commit (string): The identifier of the commit to read file from.

        Returns:
            Promise: A promise to read the content of a file from git index.

            The Promise resolves with the number of bytes written to the cache
            in case of success.

            The Promise resolves with PromiseError if the cache file could not
            be created, opened or written data to, if git failed to run or
            returned a none-zero exit code other than 128 (file not found).
        """
        if not self._git_temp_file:
            self._git_temp_file = TempFile(mode='wb')

        try:
            proc = self.popen([
                self._git_binary,
                '-c', 'core.autocrlf=input',
                '-c', 'core.eol=lf',
                '-c', 'core.safecrlf=false',
                'cat-file',
                # smudge filters are supported with git 2.11.0+ only
                '--filters' if self._git_version >= (2, 11, 0) else '-p',
                ':'.join((commit, self._git_path))
            ], stdout=self._git_temp_file.open())

        except Exception as error:
            self._git_temp_file.close()
            return Promise.resolve(PromiseError(str(error)))

        def poll(proc, resolve):
            """Poll the process and resolve promise if finished."""
            try:
                returncode = proc.poll()
                if returncode is None:
                    # git is still busy, come here later again
                    set_timeout(functools.partial(poll, proc, resolve), 50)
                    return None

                # file is still open for writing at this point
                with self._git_temp_file as file:
                    if returncode == 0:
                        # resolve with the number of bytes got from git cat-file
                        return resolve(file.tell())
                    elif returncode == 128:
                        # resolve with 0 bytes if file was not found in repo.
                        return resolve(0)
                    return resolve(PromiseError("git returned error %d: %s" % (