Most of CGLib is licensed under the terms of the MIT license.

A few exceptions are:
- cogl-point-in-poly.c is under a permissive 3 clause BSD license
- stb_image.c is public domain.

Please see individual files for details.

--
The MIT License

Copyright (C) 2007,2008 OpenedHand
Copyright (C) 2009-2015 Intel Corporation.
Copyright (C) 2010,2012 Red Hat, Inc.
Copyright (C) 1999-2005 Brian Paul   All Rights Reserved.
Copyright (C) 2011,2012 Collabora Ltd.
Copyright (C) 2008-2011 Kristian Høgsberg
Copyright (C) 2006-2011 Novell, Inc.
Copyright (C) 2011-2012 Xamarin Inc.
Copyright (C) 2011 Jeffrey Stedfast
Copyright (C) 2015-2016 Robert Bragg

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

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The BSD license used in cogl-point-in-poly.c:

Copyright (c) 1970-2003 Wm. Randolph Frianklin

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimers.
2. Redistributions in binary form must reproduce the above
   copyright notice in the documentation and/or other materials
   provided with the distribution.
3. The name of W. Randolph Franklin may not be used to endorse or
   promote products derived from this Software without specific
   prior written permission.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.