fix(dictionary): stop large character dictionaries from timing out (#189)

src/main/character-dictionary-runtime/zip.test.ts

@@ -3,7 +3,7 @@ import fs from 'node:fs';
 import os from 'node:os';
 import path from 'node:path';
 import test from 'node:test';
-import { buildDictionaryZip } from './zip';
+import { buildDictionaryZip, readDictionaryZipRevision } from './zip';
 import type { CharacterDictionaryTermEntry } from './types';
 
 function makeTempDir(): string {
@@ -105,3 +105,63 @@ test('buildDictionaryZip writes a valid stored zip without fs.writeFileSync', ()
     cleanupDir(tempDir);
   }
 });
+
+test('readDictionaryZipRevision reads the built revision and rejects foreign archives', () => {
+  const dir = makeTempDir();
+  try {
+    const zipPath = path.join(dir, 'merged.zip');
+    buildDictionaryZip(
+      zipPath,
+      'SubMiner Character Dictionary',
+      'Character names',
+      'rev-42',
+      [
+        {
+          term: 'ルフィ',
+          reading: 'ルフィ',
+          role: 'main',
+          glossary: [],
+        } as unknown as CharacterDictionaryTermEntry,
+      ],
+      [],
+    );
+
+    assert.equal(readDictionaryZipRevision(zipPath), 'rev-42');
+    assert.equal(readDictionaryZipRevision(path.join(dir, 'missing.zip')), null);
+
+    const archive = fs.readFileSync(zipPath);
+    const truncatedPath = path.join(dir, 'truncated.zip');
+    fs.writeFileSync(truncatedPath, archive.subarray(0, 40));
+    assert.equal(readDictionaryZipRevision(truncatedPath), null);
+
+    // An archive cut short after index.json still holds a readable revision, but importing it
+    // would hand Yomitan a half-written file: the missing end-of-central-directory record has to
+    // reject it. One byte off the end is enough to make the record incomplete.
+    for (const missingBytes of [1, 22, archive.length - 200]) {
+      const cutPath = path.join(dir, `cut-${missingBytes}.zip`);
+      fs.writeFileSync(cutPath, archive.subarray(0, archive.length - missingBytes));
+      assert.equal(readDictionaryZipRevision(cutPath), null, `cut of ${missingBytes} bytes`);
+    }
+
+    // Same size, corrupt directory: a record overwritten in place has to be rejected too.
+    const centralStart = archive.readUInt32LE(archive.length - 22 + 16);
+    const brokenSignaturePath = path.join(dir, 'broken-signature.zip');
+    const brokenSignature = Buffer.from(archive);
+    brokenSignature.writeUInt32LE(0xdeadbeef, centralStart);
+    fs.writeFileSync(brokenSignaturePath, brokenSignature);
+    assert.equal(readDictionaryZipRevision(brokenSignaturePath), null);
+
+    const brokenLengthPath = path.join(dir, 'broken-length.zip');
+    const brokenLength = Buffer.from(archive);
+    // Name length that runs the walk past the end of the directory.
+    brokenLength.writeUInt16LE(0xffff, centralStart + 28);
+    fs.writeFileSync(brokenLengthPath, brokenLength);
+    assert.equal(readDictionaryZipRevision(brokenLengthPath), null);
+
+    const foreignPath = path.join(dir, 'foreign.zip');
+    fs.writeFileSync(foreignPath, Buffer.from('not a zip at all', 'utf8'));
+    assert.equal(readDictionaryZipRevision(foreignPath), null);
+  } finally {
+    cleanupDir(dir);
+  }
+});