Add script to check for SPDX identifiers

scripts/spdx.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-3.0-only
+# Check that all files have a SPDX license identifier
+
+set -e
+
+# File patterns to check
+FILE_TYPES=(
+    '*.c'
+    '*.h'
+    '*.mk'
+    '*.rs'
+    '*.sh'
+    'Makefile'
+)
+
+ret=0
+
+for ft in "${FILE_TYPES[@]}"; do
+    files=$(git ls-files "$ft")
+    for f in ${files}; do
+        # Skip empty files
+        if [[ "$(wc -l < "$f")" = "0" ]]; then
+            continue
+        fi
+
+        # SPDX must appear at head of file
+        if ! head "$f" | grep -q 'SPDX-License-Identifier:'; then
+            echo "$f: Missing SPDX identifier"
+            ret=1
+        fi
+    done
+done
+
+exit ${ret}