add script for checking copyright headers

scripts/check-copyright.sh

@@ -0,0 +1,74 @@
+#!/bin/bash
+# SPDX-License-Identifier: LGPL-3.0-or-later
+# See Notices.txt for copyright information
+set -e
+
+function fail()
+{
+    local error="$1"
+    echo "error: $error" >&2
+    exit 1
+}
+
+function fail_file()
+{
+    local file="$1" line="$2" error="$3"
+    fail "$file:$((line + 1)): $error"
+}
+
+function check_file()
+{
+    local file="$1" regexes=("${@:2}")
+    local lines
+    mapfile -t lines < "$file"
+    local line
+    for line in "${!regexes[@]}"; do
+        eval '[[ "${lines[i]}" =~ '"${regexes[i]}"' ]]' ||
+            fail_file "$file" "$line" "doesn't match regex: ${regexes[i]}"
+    done
+}
+
+POUND_HEADER=('^"# SPDX-License-Identifier: LGPL-3.0-or-later"$' '^"# See Notices.txt for copyright information"$')
+SLASH_HEADER=('^"// SPDX-License-Identifier: LGPL-3.0-or-later"$' '^"// See Notices.txt for copyright information"$')
+MD_HEADER=('^"<!--"$' '^"SPDX-License-Identifier: LGPL-3.0-or-later"$' '^"See Notices.txt for copyright information"$')
+JSON_HEADER=('^"{"$' '^"    \"license_header\": ["$' '^"        \"SPDX-License-Identifier: LGPL-3.0-or-later\","$' '^"        \"See Notices.txt for copyright information\""')
+
+function main()
+{
+    local IFS=$'\n'
+    [[ -z "$(git status --porcelain)" ]] || fail "git repo is dirty"
+    local file
+    for file in $(git ls-tree --name-only --full-tree -r HEAD); do
+        case "/$file" in
+        /Cargo.lock)
+            # generated file
+            ;;
+        */LICENSE.md|*/Notices.txt)
+            # copyright file
+            ;;
+        /crates/fayalite/tests/ui/*.stderr)
+            # file that can't contain copyright header
+            ;;
+        /.forgejo/workflows/*.yml|*/.gitignore|*.toml)
+            check_file "$file" "${POUND_HEADER[@]}"
+            ;;
+        *.md)
+            check_file "$file" "${MD_HEADER[@]}"
+            ;;
+        *.sh)
+            check_file "$file" '^'\''#!'\' "${POUND_HEADER[@]}"
+            ;;
+        *.rs)
+            check_file "$file" "${SLASH_HEADER[@]}"
+            ;;
+        *.json)
+            check_file "$file" "${JSON_HEADER[@]}"
+            ;;
+        *)
+            fail_file "$file" 0 "unimplemented file kind -- you need to add it to $0"
+            ;;
+        esac
+    done
+}
+
+main