Change license of libsquashfs.so

This this commit, the code that is compiled and linked to produce
libsquashfs.so (and *only* libsquashfs.so) is released under the
terms and conditions of the GNU Lesser General Public license,
allowing 3rd party programs to dynamically link against it and still
being able to release their programs under a license of their choosing.

The libutil library is also relicensed, because it is statically linked
into libsquashfs.so. This does not affect the command line programs that
remain under the GPLv3.

At the current time, the two libraries do not contain any 3rd party
contributions and thus do not require anybodys consent other than mine
to change the licensing terms (unlike e.g. libfstree.a).

The libfstree.a and libsqfshelper.a utility libraries will also remain
under the GPLv3 license.

Going forward, some parts of libsqfshelper.a will be moved to
libsquashfs.so. The parts absorbed by libsquashfs.so will then also have
their licensing conditions changed *at that time*.

For the public headers, this commit adds the full boiler-plate comment
about the license, for the source files and internal headers, only the
SPDX identifier is changed.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 15 insertions, 2 deletions

diff --git a/include/sqfs/error.h b/include/sqfs/error.h
index 5bbf26c..a755c0b 100644
--- a/include/sqfs/error.h
+++ b/include/sqfs/error.h
@@ -1,8 +1,21 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
 /*
- * error.h
+ * error.h - This file is part of libsquashfs
  *
  * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 #ifndef SQFS_ERROR_H
 #define SQFS_ERROR_H