feat: parse bounded FSSHTTPB packages

src/onenote/fsshttpb/primitives.test.ts

@@ -0,0 +1,47 @@
+import { describe, expect, it } from 'vitest';
+
+import { BinaryReader } from '../binary/BinaryReader.js';
+import {
+  readCompactU64,
+  readFssHttpExGuid,
+  readFssHttpStreamHeader,
+} from './primitives.js';
+
+describe('FSSHTTPB primitives', () => {
+  it.each([
+    [[0x00], 0n],
+    [[(0x5a << 1) | 1], 0x5an],
+    [[0xd2, 0x48], 0x1234n],
+    [
+      [0x80, 0xef, 0xcd, 0xab, 0x89, 0x67, 0x45, 0x23, 0x01],
+      0x0123_4567_89ab_cdefn,
+    ],
+  ] as const)('decodes compact unsigned integer %j', (input, expected) => {
+    const reader = new BinaryReader(Uint8Array.from(input));
+    expect(readCompactU64(reader)).toBe(expected);
+    expect(reader.remaining).toBe(0);
+  });
+
+  it('rejects a truncated extended GUID at the original absolute offset', () => {
+    const reader = new BinaryReader(
+      Uint8Array.from([0, 0, 0x80, 1, 2]),
+      2,
+      3,
+      'test ExGuid'
+    );
+    expect(() => readFssHttpExGuid(reader)).toThrowError(
+      expect.objectContaining({ code: 'BOUNDS_EXCEEDED', offset: 3 })
+    );
+  });
+
+  it('rejects stream-object end markers where a start is required', () => {
+    const reader = new BinaryReader(Uint8Array.from([0x05]));
+    expect(() => readFssHttpStreamHeader(reader)).toThrowError(
+      expect.objectContaining({
+        code: 'INVALID_STRUCTURE',
+        offset: 0,
+        structure: 'FSSHTTPB stream object header',
+      })
+    );
+  });
+});