# License of squashfs-tools-ng

The `libsquashfs` library is released under the terms and conditions of the
**GNU Lesser General Public License version 3 or later**. This applies to
all source code in the directories `lib/sqfs` and `include/sqfs`, unless
otherwise noted.

The rest of squashfs-tools-ng is released under the terms and conditions of
the **GNU General Public License version 3 or later**.

Copies of the licenses are included in `licenses/LGPLv3.txt` and
`licenses/GPLv3.txt` respectively.

The original source code of squashfs-tools-ng has been written by David
Oberhollenzer in 2019. Additional contributions have been added since the
initial release which makes some parts of the package subject to the copyright
of the respective authors. Appropriate copyright notices and SPDX identifiers
are included in the source code files.

Although the existing squashfs-tools and the Linux kernel implementation have
been used for testing, the source code in this package is neither based on,
nor derived from either of them.

## Third Party Library Source Code

The source code of `libsquashfs` incorporates modified copies of third party
libraries that are subject to the terms and conditions of their respective
licenses.

The following is included:

 - `lib/sqfs/block_processor/xxhash.c` contains a modified implementation of
   the xxhash32 algorithm. See `licenses/xxhash.txt` for information on
   copyright and licensing terms and conditions.
 - `lib/sqfs/comp/lz4` contains files extracted from the LZ4 compression
   library. See `lib/sqfs/comp/lz4/README` for details and `licenses/LZ4.txt`
   for information on copyright and licensing terms and conditions.
 - `lib/sqfs/comp/zlib` contains files that have been extracted from the the
   zlib compression library and modified. See `lib/sqfs/comp/zlib/README` for
   details and `licenses/zlib.txt` for information on copyright and licensing
   terms and conditions.

# Binary Packages with 3rd Party Libraries

If this file is included in a binary release package, additional 3rd party
libraries may be included, which are subject to the copyright of their
respective authors and the terms and conditions of their respective liceses.

The following may be included:

 - The LZO compression library. Copyright Markus F.X.J. Oberhumer. This is
   released under the terms and conditions of the GNU General Public License
   version 2. A copy of the license is included in `licenses/GPLv2.txt`.
 - The LZ4 compression library. Copyright Yann Collet. This is released under a
   2 clause BSD style license, included in `licenses/LZ4.txt`. This library may
   be linked directly into `libsquashfs`, built from source code included in
   the source distribution.
 - The XZ utils liblzma library is released into the public domain. An excerpt
   from the `COPYING` file of its source code archive is included
   in `licenses/xz.txt`.
 - The zlib compression library. Copyright Jean-loup Gailly and Mark Adler.
   This is released under the terms and conditions of the zlib license,
   included in `licenses/zlib.txt`. This library may be linked directly
   into `libsquashfs`, built from source code included in the source
   distribution.
 - The zstd compression library. Copyright Facebook, Inc. All rights reserved.
   This is released under a BSD style license, included in `licenses/zstd.txt`.


Independend of build configurations, the `libsquashfs` library contains
the following 3rd party source code, directly linked into the library:

 - A modified version of the xxhash32 hash function (Copyright Yann Collet).
   This is released under a 2-Clause BSD License. See `licenses/xxhash.txt`
   for details.