security hardening

backend/src/executor.js

@@ -74,6 +74,21 @@ export function runRestic(args, options = {}) {
   });
 }
 
+export async function resticSnapshotFileSize(snapshotId, filename) {
+  const result = await runRestic(['ls', '--json', snapshotId]);
+  const wanted = `/${filename}`;
+  for (const line of result.stdout.split('\n')) {
+    if (!line.trim()) continue;
+    const entry = JSON.parse(line);
+    if (entry.type === 'file' && (entry.path === filename || entry.path === wanted || entry.path?.endsWith(wanted))) {
+      return Number(entry.size);
+    }
+  }
+  const error = new Error(`Could not verify Restic file size for ${filename} in snapshot ${snapshotId}.`);
+  error.status = 500;
+  throw error;
+}
+
 export function createProgressStream(totalBytes, onProgress) {
   let currentBytes = 0;
   return new Transform({