libarchive-c 5.1

Python interface to libarchive

A Python interface to libarchive. It uses the standard ctypes module to dynamically load and access the C library.

Installation

pip install libarchive-c

Compatibility

python

python-libarchive-c is currently tested with python 3.8, 3.9, 3.10 and 3.11.

If you find an incompatibility with older versions you can send us a small patch, but we won’t accept big changes.

libarchive

python-libarchive-c may not work properly with obsolete versions of libarchive such as the ones included in MacOS. In that case you can install a recent version of libarchive (e.g. with brew install libarchive on MacOS) and use the LIBARCHIVE environment variable to point python-libarchive-c to it:

export LIBARCHIVE=/usr/local/Cellar/libarchive/3.3.3/lib/libarchive.13.dylib

Usage

Import:

import libarchive

Extracting archives

To extract an archive, use the extract_file function:

os.chdir('/path/to/target/directory')
libarchive.extract_file('test.zip')

Alternatively, the extract_memory function can be used to extract from a buffer, and extract_fd from a file descriptor.

The extract_* functions all have an integer flags argument which is passed directly to the C function archive_write_disk_set_options(). You can import the EXTRACT_* constants from the libarchive.extract module and see the official description of each flag in the archive_write_disk(3) man page.

By default, when the flags argument is None, the SECURE_NODOTDOT, SECURE_NOABSOLUTEPATHS and SECURE_SYMLINKS flags are passed to libarchive, unless the current directory is the root (/).

Reading archives

To read an archive, use the file_reader function:

with libarchive.file_reader('test.7z') as archive:
    for entry in archive:
        for block in entry.get_blocks():
            ...

Alternatively, the memory_reader function can be used to read from a buffer, fd_reader from a file descriptor, stream_reader from a stream object (which must support the standard readinto method), and custom_reader from anywhere using callbacks.

To learn about the attributes of the entry object, see the libarchive/entry.py source code or run help(libarchive.entry.ArchiveEntry) in a Python shell.

Displaying progress

If your program processes large archives, you can keep track of its progress with the bytes_read attribute. Here’s an example of a progress bar using tqdm:

with tqdm(total=os.stat(archive_path).st_size, unit='bytes') as pbar, \
     libarchive.file_reader(archive_path) as archive:
    for entry in archive:
        ...
        pbar.update(archive.bytes_read - pbar.n)

Creating archives

To create an archive, use the file_writer function:

from libarchive.entry import FileType

with libarchive.file_writer('test.tar.gz', 'ustar', 'gzip') as archive:
    # Add the `libarchive/` directory and everything in it (recursively),
    # then the `README.rst` file.
    archive.add_files('libarchive/', 'README.rst')
    # Add a regular file defined from scratch.
    data = b'foobar'
    archive.add_file_from_memory('../escape-test', len(data), data)
    # Add a directory defined from scratch.
    early_epoch = (42, 42)  # 1970-01-01 00:00:42.000000042
    archive.add_file_from_memory(
        'metadata-test', 0, b'',
        filetype=FileType.DIRECTORY, permission=0o755, uid=4242, gid=4242,
        atime=early_epoch, mtime=early_epoch, ctime=early_epoch, birthtime=early_epoch,
    )

Alternatively, the memory_writer function can be used to write to a memory buffer, fd_writer to a file descriptor, and custom_writer to a callback function.

For each of those functions, the mandatory second argument is the archive format, and the optional third argument is the compression format (called “filter” in libarchive). The acceptable values are listed in libarchive.ffi.WRITE_FORMATS and libarchive.ffi.WRITE_FILTERS.

File metadata codecs

By default, UTF-8 is used to read and write file attributes from and to archives. A different codec can be specified through the header_codec arguments of the *_reader and *_writer functions. Example:

with libarchive.file_writer('test.tar', 'ustar', header_codec='cp037') as archive:
    ...
with file_reader('test.tar', header_codec='cp037') as archive:
    ...

In addition to file paths (pathname and linkpath), the specified codec is used to encode and decode user and group names (uname and gname).

License

CC0 Public Domain Dedication