How to use the pygit2.ffi.ffi.new function in pygit2

if committish:
            if isinstance(committish, str):
                committish = self.revparse_single(committish)

            commit = committish.peel(Commit)

            cptr = ffi.new('git_object **')
            ffi.buffer(cptr)[:] = commit._pointer[:]

            err = C.git_describe_commit(result, cptr[0], options)
        else:
            err = C.git_describe_workdir(result, self._repo, options)
        check_error(err)

        try:
            format_options = ffi.new('git_describe_format_options *')
            C.git_describe_init_format_options(format_options, C.GIT_DESCRIBE_FORMAT_OPTIONS_VERSION)

            if abbreviated_size is not None:
                format_options.abbreviated_size = abbreviated_size
            if always_use_long_format is not None:
                format_options.always_use_long_format = always_use_long_format
            dirty_ptr = None
            if dirty_suffix:
                dirty_ptr = ffi.new('char[]', to_bytes(dirty_suffix))
                format_options.dirty_suffix = dirty_ptr

            buf = ffi.new('git_buf *', (ffi.NULL, 0))

            err = C.git_describe_format(buf, result[0], format_options)
            check_error(err)

Index that reflects the result of the revert.

        Returns: an Index with the result of the revert.

        Parameters:

        revert_commit
            The Commit to revert.

        our_commit
            The Commit to revert against (eg, HEAD).

        mainline
            The parent of the revert Commit, if it is a merge (i.e. 1, 2).
        """
        cindex = ffi.new('git_index **')
        revert_commit_ptr = ffi.new('git_commit **')
        our_commit_ptr = ffi.new('git_commit **')

        ffi.buffer(revert_commit_ptr)[:] = revert_commit._pointer[:]
        ffi.buffer(our_commit_ptr)[:] = our_commit._pointer[:]

        opts = ffi.new('git_merge_options *')
        err = C.git_merge_init_options(opts, C.GIT_MERGE_OPTIONS_VERSION)
        check_error(err)

        err = C.git_revert_commit(
            cindex, self._repo, revert_commit_ptr[0], our_commit_ptr[0], mainline, opts
        )
        check_error(err)

        return Index.from_c(self, cindex)

def rename(self, name, new_name):
        """Rename a remote in the configuration. The refspecs in standard
        format will be renamed.

        Returns a list of fetch refspecs (list of strings) which were not in
        the standard format and thus could not be remapped.
        """

        if not new_name:
            raise ValueError("Current remote name must be a non-empty string")

        if not new_name:
            raise ValueError("New remote name must be a non-empty string")

        problems = ffi.new('git_strarray *')
        err = C.git_remote_rename(problems, self._repo._repo, to_bytes(name), to_bytes(new_name))
        check_error(err)

        ret = strarray_to_strings(problems)
        C.git_strarray_free(problems)

        return ret

def __iter__(self):
        names = ffi.new('git_strarray *')

        try:
            err = C.git_remote_list(names, self._repo._repo)
            check_error(err)

            cremote = ffi.new('git_remote **')
            for i in range(names.count):
                err = C.git_remote_lookup(cremote, self._repo._repo, names.strings[i])
                check_error(err)

                yield Remote(self._repo, cremote[0])
        finally:
            C.git_strarray_free(names)

def get_multivar(self, name, regex=None):
        """Get each value of a multivar ''name'' as a list of strings.

        The optional ''regex'' parameter is expected to be a regular expression
        to filter the variables we're interested in.
        """
        assert_string(name, "name")

        citer = ffi.new('git_config_iterator **')
        err = C.git_config_multivar_iterator_new(citer, self._config,
                                                 to_bytes(name),
                                                 to_bytes(regex))
        check_error(err)

        return ConfigMultivarIterator(self, citer[0])

def _get(self, key):
        assert_string(key, "key")

        entry = ffi.new('git_config_entry **')
        err = C.git_config_get_entry(entry, self._config, to_bytes(key))

        return err, ConfigEntry._from_c(entry[0])

def _checkout_args_to_options(strategy=None, directory=None, paths=None):
        # Create the options struct to pass
        copts = ffi.new('git_checkout_options *')
        check_error(C.git_checkout_init_options(copts, 1))

        # References we need to keep to strings and so forth
        refs = []

        # pygit2's default is SAFE | RECREATE_MISSING
        copts.checkout_strategy = GIT_CHECKOUT_SAFE | GIT_CHECKOUT_RECREATE_MISSING
        # and go through the arguments to see what the user wanted
        if strategy:
            copts.checkout_strategy = strategy

        if directory:
            target_dir = ffi.new('char[]', to_bytes(directory))
            refs.append(target_dir)
            copts.target_directory = target_dir

        if paths:
            strarray = StrArray(paths)
            refs.append(strarray)
            copts.paths = strarray.array[0]

        return copts, refs

def lookup_submodule(self, path):
        csub = ffi.new('git_submodule **')
        cpath = ffi.new('char[]', to_bytes(path))

        err = C.git_submodule_lookup(csub, self._repo, cpath)
        check_error(err)
        return Submodule._from_c(self, csub[0])