Differential updates

ts/scripts/generate-fixtures.ts

@@ -0,0 +1,53 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import fs from 'fs/promises';
+import path from 'path';
+import crypto from 'crypto';
+import { execFileSync } from 'child_process';
+
+const FIXTURES = path.join(__dirname, '..', '..', 'fixtures');
+const SIZE = 256 * 1024;
+
+async function main() {
+  const original = crypto.randomBytes(SIZE);
+
+  const originalPath = path.join(FIXTURES, 'diff-original.bin');
+  await fs.writeFile(originalPath, original);
+
+  // Add a broken byte to help create useful blockmaps
+  original[Math.floor(Math.random() * original.length)] = 0;
+
+  const modifiedPath = path.join(FIXTURES, 'diff-modified.bin');
+  await fs.writeFile(modifiedPath, original);
+
+  const appBuilder = path.join(
+    __dirname,
+    '..',
+    '..',
+    'node_modules',
+    'app-builder-bin',
+    'mac',
+    'app-builder_amd64'
+  );
+
+  for (const filePath of [originalPath, modifiedPath]) {
+    console.log('Adding blockmap to', filePath);
+
+    // Put blockmap into a separate file
+    console.log(
+      execFileSync(appBuilder, [
+        'blockmap',
+        '--input',
+        filePath,
+        '--output',
+        `${filePath}.blockmap`,
+      ]).toString()
+    );
+  }
+}
+
+main().catch(err => {
+  console.error(err);
+  process.exit(1);
+});