add copyright headers+enforce w/ addlicense

.drone.starlark

@@ -1,3 +1,6 @@
+# Copyright 2022 wanderer <a_mirre at utb dot cz>
+# SPDX-License-Identifier: GPL-3.0-or-later
+
 # vim: ft=bzl.starlark noexpandtab tw=4 ts=4
 def main(ctx):
 	return [

.pre-commit-config.yaml

@@ -1,3 +1,6 @@
+# Copyright 2022 wanderer <a_mirre at utb dot cz>
+# SPDX-License-Identifier: GPL-3.0-or-later
+
 ---
 fail_fast: false
 repos:
@@ -28,6 +31,15 @@ repos:
         pass_filenames: false
         files: "flake.nix"
         language: system
+      - id: addlicense
+        require_serial: false
+        name: addlicence -check
+        entry: >
+          go run github.com/google/addlicense@v1.0.0 -check -v
+        pass_filenames: true
+        types_or: ["go", "yaml"]
+        exclude: "^.drone.*"
+        language: system
   - repo: https://github.com/dnephin/pre-commit-golang
     rev: v0.5.0
     hooks:

cmd/root.go

@@ -1,3 +1,6 @@
+// Copyright 2022 wanderer <a_mirre at utb dot cz>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package cmd
 
 import (

cmd/root_test.go

@@ -1,3 +1,6 @@
+// Copyright 2022 wanderer <a_mirre at utb dot cz>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package cmd
 
 import (

cmd/version.go

@@ -1,3 +1,6 @@
+// Copyright 2022 wanderer <a_mirre at utb dot cz>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package cmd
 
 import (

cmd/version_test.go

@@ -1,3 +1,6 @@
+// Copyright 2022 wanderer <a_mirre at utb dot cz>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package cmd
 
 import (

main.go

@@ -1,3 +1,6 @@
+// Copyright 2022 wanderer <a_mirre at utb dot cz>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package main
 
 import (

main_test.go

@@ -1,3 +1,6 @@
+// Copyright 2022 wanderer <a_mirre at utb dot cz>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package main
 
 import (

xkcdreader/app.go

@@ -1,3 +1,6 @@
+// Copyright 2022 wanderer <a_mirre at utb dot cz>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package xkcdreader
 
 import (

xkcdreader/app_test.go

@@ -1,3 +1,6 @@
+// Copyright 2022 wanderer <a_mirre at utb dot cz>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package xkcdreader
 
 import (