fix: reject stale first-boot scripts in OTA release payloads

scripts/check-ota-runtime.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+"""Reject OTA archives that would overwrite the qualified first-boot repair."""
+import argparse
+import pathlib
+import tarfile
+
+
+def check(archive, source):
+    member_name = 'archipelago-runtime/scripts/first-boot-containers.sh'
+    with tarfile.open(archive, 'r:gz') as package:
+        matches = [m for m in package.getmembers()
+                   if m.name.removeprefix('./') == member_name]
+        if len(matches) != 1 or not matches[0].isfile():
+            raise ValueError('OTA must contain exactly one regular first-boot script')
+        with package.extractfile(matches[0]) as stream:
+            actual = stream.read()
+    if actual != source.read_bytes():
+        raise ValueError('OTA first-boot script differs from qualified source; repackage before signing')
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('archive', type=pathlib.Path)
+    args = parser.parse_args()
+    try:
+        check(args.archive, pathlib.Path(__file__).resolve().parents[1] /
+              'scripts/first-boot-containers.sh')
+    except (OSError, ValueError, tarfile.TarError) as error:
+        parser.exit(1, f'FAIL: {error}\n')
+    print('PASS: OTA first-boot script matches qualified source')
+
+
+if __name__ == '__main__':
+    main()