fix(dictionary): prevent freezes and restore AppImage notifications (#205)

src/shared/stored-zip.test.ts

@@ -0,0 +1,74 @@
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import test from 'node:test';
+import { readStoredZipFirstFile, writeStoredZip, writeStoredZipAsync } from './stored-zip';
+
+function makeTempDir(): string {
+  return fs.mkdtempSync(path.join(os.tmpdir(), 'subminer-stored-zip-'));
+}
+
+function readEntries(zipPath: string): Map<string, Buffer> {
+  const archive = fs.readFileSync(zipPath);
+  const entries = new Map<string, Buffer>();
+  let cursor = 0;
+
+  while (cursor + 4 <= archive.length) {
+    const signature = archive.readUInt32LE(cursor);
+    if (signature === 0x02014b50 || signature === 0x06054b50) {
+      break;
+    }
+    assert.equal(signature, 0x04034b50, `unexpected local file header at offset ${cursor}`);
+    const size = archive.readUInt32LE(cursor + 18);
+    const nameLength = archive.readUInt16LE(cursor + 26);
+    const extraLength = archive.readUInt16LE(cursor + 28);
+    const nameStart = cursor + 30;
+    const dataStart = nameStart + nameLength + extraLength;
+    entries.set(
+      archive.subarray(nameStart, nameStart + nameLength).toString('utf8'),
+      Buffer.from(archive.subarray(dataStart, dataStart + size)),
+    );
+    cursor = dataStart + size;
+  }
+
+  return entries;
+}
+
+// The async writer yields on a byte budget between entries, so an entry that is itself larger than
+// that budget is the case where the accounting could drift: the offsets, CRCs, and central
+// directory all have to come out identical to the synchronous writer.
+test('writeStoredZipAsync writes a correct archive when one entry exceeds the yield budget', async () => {
+  const dir = makeTempDir();
+  try {
+    // Comfortably past the writer's 8MB yield budget.
+    const oversized = Buffer.alloc(10 * 1024 * 1024);
+    for (let i = 0; i < oversized.length; i += 1) {
+      oversized[i] = i % 251;
+    }
+    const files = [
+      { name: 'index.json', data: Buffer.from('{"revision":"rev-1"}', 'utf8') },
+      { name: 'big.bin', data: oversized },
+      { name: 'after.txt', data: Buffer.from('written after the oversized entry', 'utf8') },
+    ];
+
+    const asyncPath = path.join(dir, 'async.zip');
+    const syncPath = path.join(dir, 'sync.zip');
+    const asyncResult = await writeStoredZipAsync(asyncPath, files);
+    const syncResult = writeStoredZip(syncPath, files);
+
+    assert.equal(asyncResult.entryCount, 3);
+    assert.deepEqual(asyncResult, syncResult);
+    // Byte-identical to the synchronous writer: yielding mid-archive changed no offset or CRC.
+    assert.ok(fs.readFileSync(asyncPath).equals(fs.readFileSync(syncPath)));
+
+    const entries = readEntries(asyncPath);
+    assert.deepEqual([...entries.keys()], ['index.json', 'big.bin', 'after.txt']);
+    assert.ok(entries.get('big.bin')!.equals(oversized));
+    assert.equal(entries.get('after.txt')!.toString('utf8'), 'written after the oversized entry');
+    // The trailing records still parse, which is what proves the archive is complete.
+    assert.equal(readStoredZipFirstFile(asyncPath)?.name, 'index.json');
+  } finally {
+    fs.rmSync(dir, { recursive: true, force: true });
+  }
+});