Add database backup and restore

scripts/verify-backup.py

@@ -0,0 +1,42 @@
+#!/usr/bin/env python3
+"""Restore a backup to an isolated temporary database and verify its integrity."""
+
+import argparse
+import shutil
+import sqlite3
+import sys
+import tempfile
+from pathlib import Path
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Test an Eternity Project database backup by restoring it safely.")
+    parser.add_argument("backup", type=Path, help="Path to a .db backup created by backup-database.py")
+    args = parser.parse_args()
+    source = args.backup.resolve()
+    if not source.is_file():
+        print(f"BACKUP_VERIFY_FAILED: Backup does not exist: {source}", file=sys.stderr)
+        return 2
+
+    with tempfile.TemporaryDirectory(prefix="eternity-restore-") as directory:
+        restored = Path(directory) / "eternity-restored.db"
+        shutil.copy2(source, restored)
+        try:
+            database = sqlite3.connect(f"file:{restored}?mode=ro", uri=True)
+            integrity = database.execute("PRAGMA integrity_check").fetchone()[0]
+            users = database.execute("SELECT COUNT(*) FROM users").fetchone()[0]
+            posts = database.execute("SELECT COUNT(*) FROM posts").fetchone()[0]
+            database.close()
+        except sqlite3.DatabaseError as error:
+            print(f"BACKUP_VERIFY_FAILED: {error}", file=sys.stderr)
+            return 1
+
+    if integrity != "ok":
+        print(f"BACKUP_VERIFY_FAILED: integrity_check returned {integrity}", file=sys.stderr)
+        return 1
+    print(f"BACKUP_RESTORE_VERIFIED: users={users} posts={posts} source={source}")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())