use SPDX-License-Identifier in source files

49 files changed, 65 insertions, 141 deletions

diff --git a/src/apk.c b/src/apk.c
index bb0dc79..8fbc3e8 100644
--- a/src/apk.c
+++ b/src/apk.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/apk_applet.h b/src/apk_applet.h
index f1bf9b2..e682314 100644
--- a/src/apk_applet.h
+++ b/src/apk_applet.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_APPLET_H
diff --git a/src/apk_archive.h b/src/apk_archive.h
index bd24733..708fd1a 100644
--- a/src/apk_archive.h
+++ b/src/apk_archive.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_ARCHIVE
diff --git a/src/apk_blob.h b/src/apk_blob.h
index 91ba9b3..84bd143 100644
--- a/src/apk_blob.h
+++ b/src/apk_blob.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_BLOB_H
diff --git a/src/apk_database.h b/src/apk_database.h
index bcd5719..dc6525f 100644
--- a/src/apk_database.h
+++ b/src/apk_database.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_PKGDB_H
diff --git a/src/apk_defines.h b/src/apk_defines.h
index 1cd8b6c..dfdb32a 100644
--- a/src/apk_defines.h
+++ b/src/apk_defines.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_DEFINES_H
diff --git a/src/apk_hash.h b/src/apk_hash.h
index 8fad7f7..a8eb33b 100644
--- a/src/apk_hash.h
+++ b/src/apk_hash.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_HASH_H
diff --git a/src/apk_io.h b/src/apk_io.h
index fb784c3..e4759b0 100644
--- a/src/apk_io.h
+++ b/src/apk_io.h
@@ -3,9 +3,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_IO
diff --git a/src/apk_openssl.h b/src/apk_openssl.h
index c45beb9..4ee6da2 100644
--- a/src/apk_openssl.h
+++ b/src/apk_openssl.h
@@ -1,3 +1,12 @@
+/* apk_openssl.h - Alpine Package Keeper (APK)
+ *
+ * Copyright (C) 2005-2008 Natanael Copa <n@tanael.org>
+ * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ */
+
 #ifndef APK_SSL_COMPAT_H
 #define APK_SSL_COMPAT_H
 
diff --git a/src/apk_package.h b/src/apk_package.h
index fc43a61..08de452 100644
--- a/src/apk_package.h
+++ b/src/apk_package.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_PKG_H
diff --git a/src/apk_print.h b/src/apk_print.h
index 3f0c544..acc6981 100644
--- a/src/apk_print.h
+++ b/src/apk_print.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_PRINT_H
diff --git a/src/apk_provider_data.h b/src/apk_provider_data.h
index 15fba5c..a37e363 100644
--- a/src/apk_provider_data.h
+++ b/src/apk_provider_data.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2012 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_PROVIDER_DATA_H
diff --git a/src/apk_solver.h b/src/apk_solver.h
index 0565c26..35ef4f8 100644
--- a/src/apk_solver.h
+++ b/src/apk_solver.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2013 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_SOLVER_H
diff --git a/src/apk_solver_data.h b/src/apk_solver_data.h
index 34ce812..8aee485 100644
--- a/src/apk_solver_data.h
+++ b/src/apk_solver_data.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2012 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_SOLVER_DATA_H
diff --git a/src/apk_version.h b/src/apk_version.h
index 47a6b73..ac6d50c 100644
--- a/src/apk_version.h
+++ b/src/apk_version.h
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it 
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #ifndef APK_VERSION_H
diff --git a/src/app_add.c b/src/app_add.c
index 9331fb8..fb6e0e0 100644
--- a/src/app_add.c
+++ b/src/app_add.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <errno.h>
diff --git a/src/app_audit.c b/src/app_audit.c
index 4e59ddf..fb2a0ee 100644
--- a/src/app_audit.c
+++ b/src/app_audit.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <errno.h>
diff --git a/src/app_cache.c b/src/app_cache.c
index 2d86c59..8f38807 100644
--- a/src/app_cache.c
+++ b/src/app_cache.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <fcntl.h>
diff --git a/src/app_del.c b/src/app_del.c
index 989f0e9..32398b3 100644
--- a/src/app_del.c
+++ b/src/app_del.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/app_dot.c b/src/app_dot.c
index 548e6e3..89e385a 100644
--- a/src/app_dot.c
+++ b/src/app_dot.c
@@ -3,9 +3,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/app_fetch.c b/src/app_fetch.c
index a0bb40b..8e73c0e 100644
--- a/src/app_fetch.c
+++ b/src/app_fetch.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/app_fix.c b/src/app_fix.c
index d5f1cc7..43e6f7e 100644
--- a/src/app_fix.c
+++ b/src/app_fix.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <errno.h>
diff --git a/src/app_index.c b/src/app_index.c
index 8a9ba8c..4c0b0d1 100644
--- a/src/app_index.c
+++ b/src/app_index.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <errno.h>
diff --git a/src/app_info.c b/src/app_info.c
index 553dd2e..41d6a99 100644
--- a/src/app_info.c
+++ b/src/app_info.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/app_list.c b/src/app_list.c
index 7f141f5..ab5c846 100644
--- a/src/app_list.c
+++ b/src/app_list.c
@@ -5,9 +5,7 @@
  * Copyright (C) 2018 William Pitcock <nenolod@dereferenced.org>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/app_manifest.c b/src/app_manifest.c
index 757c8a9..cd5b2ef 100644
--- a/src/app_manifest.c
+++ b/src/app_manifest.c
@@ -5,9 +5,7 @@
  * Copyright (C) 2017 William Pitcock <nenolod@dereferenced.org>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/app_policy.c b/src/app_policy.c
index 4992858..954eb9d 100644
--- a/src/app_policy.c
+++ b/src/app_policy.c
@@ -3,9 +3,7 @@
  * Copyright (C) 2013 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/app_search.c b/src/app_search.c
index 823bc67..5f6f431 100644
--- a/src/app_search.c
+++ b/src/app_search.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <fnmatch.h>
diff --git a/src/app_stats.c b/src/app_stats.c
index f800777..583e4c6 100644
--- a/src/app_stats.c
+++ b/src/app_stats.c
@@ -3,9 +3,7 @@
  * Copyright (C) 2013 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/app_update.c b/src/app_update.c
index f79655e..70b7460 100644
--- a/src/app_update.c
+++ b/src/app_update.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/app_upgrade.c b/src/app_upgrade.c
index 5eda0eb..0c8d4dd 100644
--- a/src/app_upgrade.c
+++ b/src/app_upgrade.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <errno.h>
diff --git a/src/app_verify.c b/src/app_verify.c
index 264610f..7975268 100644
--- a/src/app_verify.c
+++ b/src/app_verify.c
@@ -3,9 +3,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <errno.h>
diff --git a/src/app_version.c b/src/app_version.c
index eb6922d..df2506c 100644
--- a/src/app_version.c
+++ b/src/app_version.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/blob.c b/src/blob.c
index 69d6d0e..fdcd1d1 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <malloc.h>
diff --git a/src/commit.c b/src/commit.c
index a441927..8c337e3 100644
--- a/src/commit.c
+++ b/src/commit.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2013 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <limits.h>
diff --git a/src/common.c b/src/common.c
index 0336645..14a56a3 100644
--- a/src/common.c
+++ b/src/common.c
@@ -3,9 +3,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <malloc.h>
diff --git a/src/database.c b/src/database.c
index dd27e2a..65d07e2 100644
--- a/src/database.c
+++ b/src/database.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <errno.h>
diff --git a/src/hash.c b/src/hash.c
index e59dac4..28301d4 100644
--- a/src/hash.c
+++ b/src/hash.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include "apk_defines.h"
diff --git a/src/help.c b/src/help.c
index ece6845..e148f26 100644
--- a/src/help.c
+++ b/src/help.c
@@ -3,9 +3,7 @@
  * Copyright (C) 2020 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <zlib.h>
diff --git a/src/io.c b/src/io.c
index 6b017ab..92f1a32 100644
--- a/src/io.c
+++ b/src/io.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <errno.h>
diff --git a/src/io_archive.c b/src/io_archive.c
index 1d34927..79cfd74 100644
--- a/src/io_archive.c
+++ b/src/io_archive.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/io_gunzip.c b/src/io_gunzip.c
index b7fa9f4..41dc5e7 100644
--- a/src/io_gunzip.c
+++ b/src/io_gunzip.c
@@ -3,9 +3,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <errno.h>
diff --git a/src/io_url.c b/src/io_url.c
index cd3f26c..93728aa 100644
--- a/src/io_url.c
+++ b/src/io_url.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdio.h>
diff --git a/src/lua-apk.c b/src/lua-apk.c
index 73c33e9..fa153e1 100644
--- a/src/lua-apk.c
+++ b/src/lua-apk.c
@@ -1,3 +1,12 @@
+/* src/lua-apk.c - Alpine Package Keeper (APK)
+ *
+ * Copyright (C) 2005-2008 Natanael Copa <n@tanael.org>
+ * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ */
+
 #include <features.h>
 #include <lua.h>
 #include <lualib.h>
diff --git a/src/package.c b/src/package.c
index 6cfb8d4..4514ad7 100644
--- a/src/package.c
+++ b/src/package.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <errno.h>
diff --git a/src/print.c b/src/print.c
index 6b8c2ed..0b79752 100644
--- a/src/print.c
+++ b/src/print.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <assert.h>
diff --git a/src/solver.c b/src/solver.c
index 25ea471..0881196 100644
--- a/src/solver.c
+++ b/src/solver.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2013 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include <stdint.h>
diff --git a/src/template.c b/src/template.c
index 37bd9ab..fb706d1 100644
--- a/src/template.c
+++ b/src/template.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it 
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 
 #include "apk_database.h"
diff --git a/src/version.c b/src/version.c
index dacbc34..dc874a6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -4,9 +4,7 @@
  * Copyright (C) 2008-2011 Timo Teräs <timo.teras@iki.fi>
  * All rights reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ * SPDX-License-Identifier: GPL-2.0-only
  */
 #include <stdio.h>