Clarify licenses

- add license headers to everything
- convert a few files from public domain or LGPL2.1+ to GPL2+
- some archaeology to clarify which files are from which library

7 files changed, 38 insertions, 18 deletions

diff --git a/src/extension/internal/pdfinput/pdf-input.cpp b/src/extension/internal/pdfinput/pdf-input.cpp
index 1c9dd9223..8b4cc5aa7 100644
--- a/src/extension/internal/pdfinput/pdf-input.cpp
+++ b/src/extension/internal/pdfinput/pdf-input.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Native PDF import using libpoppler.
  *
@@ -7,7 +8,7 @@
  *
  * Copyright (C) 2007 Authors
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  *
  */
 
diff --git a/src/extension/internal/pdfinput/pdf-input.h b/src/extension/internal/pdfinput/pdf-input.h
index ecd996632..ab9a928a2 100644
--- a/src/extension/internal/pdfinput/pdf-input.h
+++ b/src/extension/internal/pdfinput/pdf-input.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef SEEN_EXTENSION_INTERNAL_PDFINPUT_H
 #define SEEN_EXTENSION_INTERNAL_PDFINPUT_H
 
@@ -7,7 +8,7 @@
  *
  * Copyright (C) 2007 Authors
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifdef HAVE_CONFIG_H
diff --git a/src/extension/internal/pdfinput/pdf-parser.cpp b/src/extension/internal/pdfinput/pdf-parser.cpp
index bc7ad8a6e..1f609377f 100644
--- a/src/extension/internal/pdfinput/pdf-parser.cpp
+++ b/src/extension/internal/pdfinput/pdf-parser.cpp
@@ -1,14 +1,13 @@
- /*
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
  * PDF parsing using libpoppler.
- *
- * Derived from poppler's Gfx.cc
- *
+ *//*
  * Authors:
- *   Jon A. Cruz <jon@joncruz.org>
- *
- * Copyright 2012 authors
- * Copyright 1996-2003 Glyph & Cog, LLC
+ * Derived from poppler's Gfx.cc, which was derived from Xpdf by 1996-2003 Glyph & Cog, LLC
+ * Jon A. Cruz <jon@joncruz.org>
  *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifdef HAVE_CONFIG_H
diff --git a/src/extension/internal/pdfinput/pdf-parser.h b/src/extension/internal/pdfinput/pdf-parser.h
index 2414bd376..2d4441a22 100644
--- a/src/extension/internal/pdfinput/pdf-parser.h
+++ b/src/extension/internal/pdfinput/pdf-parser.h
@@ -1,8 +1,14 @@
- /*
- * Derived from Gfx.h
- *
- * Copyright 1996-2003 Glyph & Cog, LLC
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * PDF parsing using libpoppler.
+ *//*
+ * Authors:
+ * see git history
+ * 
+ * Derived from Gfx.h from poppler (?) which derives from Xpdf, Copyright 1996-2003 Glyph & Cog, LLC, which is under GPL2+.
  *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef PDF_PARSER_H
diff --git a/src/extension/internal/pdfinput/poppler-transition-api.h b/src/extension/internal/pdfinput/poppler-transition-api.h
index 443705259..5141bf8a7 100644
--- a/src/extension/internal/pdfinput/poppler-transition-api.h
+++ b/src/extension/internal/pdfinput/poppler-transition-api.h
@@ -1,3 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO short description
+ *//*
+ * Authors:
+ *   see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
 #ifndef SEEN_POPPLER_TRANSITION_API_H
 #define SEEN_POPPLER_TRANSITION_API_H
 
diff --git a/src/extension/internal/pdfinput/svg-builder.cpp b/src/extension/internal/pdfinput/svg-builder.cpp
index 481e1b95d..373df6a39 100644
--- a/src/extension/internal/pdfinput/svg-builder.cpp
+++ b/src/extension/internal/pdfinput/svg-builder.cpp
@@ -1,13 +1,14 @@
- /*
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
  * Native PDF import using libpoppler.
- * 
+ *
  * Authors:
  *   miklos erdelyi
  *   Jon A. Cruz <jon@joncruz.org>
  *
  * Copyright (C) 2007 Authors
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  *
  */
 
diff --git a/src/extension/internal/pdfinput/svg-builder.h b/src/extension/internal/pdfinput/svg-builder.h
index c61f2cc40..8168617f6 100644
--- a/src/extension/internal/pdfinput/svg-builder.h
+++ b/src/extension/internal/pdfinput/svg-builder.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef SEEN_EXTENSION_INTERNAL_PDFINPUT_SVGBUILDER_H
 #define SEEN_EXTENSION_INTERNAL_PDFINPUT_SVGBUILDER_H
 
@@ -7,7 +8,7 @@
  *
  * Copyright (C) 2007 Authors
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifdef HAVE_CONFIG_H