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tar.py

ofrak_components.tar

TarArchive (GenericBinary, FilesystemRoot) dataclass

Filesystem stored in a tar archive.

TarPacker (Packer)

Pack files into a tar archive.

pack(self, resource, config) async

Pack the given resource.

Users should not call this method directly; rather, they should run Resource.run or Resource.pack.

Parameters:

Name Type Description Default
resource Resource required
config ~CC

Optional config for packing. If an implementation provides a default, this default will always be used when config would otherwise be None. Note that a copy of the default config will be passed, so the default config values cannot be modified persistently by a component run.

required
Source code in ofrak_components/tar.py
async def pack(self, resource: Resource, config: CC) -> None:
    # Flush the child files to the filesystem
    tar_view = await resource.view_as(TarArchive)
    flush_dir = await tar_view.flush_to_disk()

    # Pack it back into a temporary archive
    with tempfile.NamedTemporaryFile(suffix=".tar") as temp_archive:
        command = ["tar", "--xattrs", "-C", flush_dir, "-cf", temp_archive.name, "."]
        try:
            subprocess.run(command, check=True, capture_output=True)
        except subprocess.CalledProcessError as e:
            raise PackerError(format_called_process_error(e))

        # Replace the original archive data
        resource.queue_patch(Range(0, await resource.get_data_length()), temp_archive.read())

TarUnpacker (Unpacker)

Unpack a tar archive.

unpack(self, resource, config) async

Unpack the given resource.

Users should not call this method directly; rather, they should run Resource.run or Resource.unpack.

Parameters:

Name Type Description Default
resource Resource

The resource that is being unpacked

required
config ~CC

Optional config for unpacking. If an implementation provides a default, this default will always be used when config would otherwise be None. Note that a copy of the default config will be passed, so the default config values cannot be modified persistently by a component run.

required
Source code in ofrak_components/tar.py
async def unpack(self, resource: Resource, config: CC) -> None:
    # Write the archive data to a file
    with tempfile.NamedTemporaryFile(suffix=".tar") as temp_archive:
        temp_archive.write(await resource.get_data())
        temp_archive.flush()

        # Check the archive member files to ensure none unpack to a parent directory
        command = ["tar", "-P", "-tf", temp_archive.name]
        try:
            output = subprocess.run(command, check=True, capture_output=True)
        except subprocess.CalledProcessError as e:
            raise UnpackerError(format_called_process_error(e))
        for filename in output.stdout.decode().splitlines():
            # Handles relative parent paths and rooted paths, and normalizes paths like "./../"
            rel_filename = os.path.relpath(filename)
            if rel_filename.startswith("../"):
                raise UnpackerError(
                    f"Tar archive contains a file {filename} that would extract to a parent "
                    f"directory {rel_filename}."
                )

        # Unpack into a temporary directory using the temporary file
        with tempfile.TemporaryDirectory() as temp_dir:
            command = ["tar", "--xattrs", "-C", temp_dir, "-xf", temp_archive.name]
            try:
                subprocess.run(command, check=True, capture_output=True)
            except subprocess.CalledProcessError as e:
                raise UnpackerError(format_called_process_error(e))

            # Initialize a filesystem from the unpacked/untarred temporary folder
            tar_view = await resource.view_as(TarArchive)
            await tar_view.initialize_from_disk(temp_dir)