test_runner: avoid hanging on incomplete v8 frames

thisalihassan · aduh95 · commit df183d7bfa52 · 2026-06-18T00:15:54.000+02:00
Signed-off-by: Ali Hassan <ali-hassan27@outlook.com> PR-URL: #62704 Reviewed-By: Moshe Atlow <moshe@atlow.co.il> Reviewed-By: Chemi Atlow <chemi@atlow.co.il>
diff --git a/lib/internal/test_runner/runner.js b/lib/internal/test_runner/runner.js
@@ -25,6 +25,7 @@ const {
   SafePromiseAllSettledReturnVoid,
   SafeSet,
   String,
+  StringFromCharCode,
   StringPrototypeIndexOf,
   StringPrototypeSlice,
   StringPrototypeStartsWith,
@@ -248,6 +249,7 @@ class FileTest extends Test {
   #rawBuffer = []; // Raw data waiting to be parsed
   #rawBufferSize = 0;
   #reportedChildren = 0;
+  #pendingPartialV8Header = false;
   failedSubtests = false;
 
   constructor(options) {
@@ -339,6 +341,12 @@ class FileTest extends Test {
   }
   parseMessage(readData) {
     let dataLength = TypedArrayPrototypeGetLength(readData);
+    if (this.#pendingPartialV8Header) {
+      readData = Buffer.concat([TypedArrayPrototypeSubarray(v8Header, 0, 1), readData]);
+      dataLength = TypedArrayPrototypeGetLength(readData);
+      this.#pendingPartialV8Header = false;
+    }
+
     if (dataLength === 0) return;
     const partialV8Header = readData[dataLength - 1] === v8Header[0];
 
@@ -349,22 +357,52 @@ class FileTest extends Test {
       dataLength--;
     }
 
-    if (this.#rawBuffer[0] && TypedArrayPrototypeGetLength(this.#rawBuffer[0]) < kSerializedSizeHeader) {
-      this.#rawBuffer[0] = Buffer.concat([this.#rawBuffer[0], readData]);
-    } else {
-      ArrayPrototypePush(this.#rawBuffer, readData);
+    if (dataLength > 0) {
+      if (this.#rawBuffer[0] && TypedArrayPrototypeGetLength(this.#rawBuffer[0]) < kSerializedSizeHeader) {
+        this.#rawBuffer[0] = Buffer.concat([this.#rawBuffer[0], readData]);
+      } else {
+        ArrayPrototypePush(this.#rawBuffer, readData);
+      }
+      this.#rawBufferSize += dataLength;
+      this.#processRawBuffer();
     }
-    this.#rawBufferSize += dataLength;
-    this.#processRawBuffer();
 
     if (partialV8Header) {
-      ArrayPrototypePush(this.#rawBuffer, TypedArrayPrototypeSubarray(v8Header, 0, 1));
-      this.#rawBufferSize++;
+      this.#pendingPartialV8Header = true;
     }
   }
   #drainRawBuffer() {
+    if (this.#pendingPartialV8Header) {
+      ArrayPrototypePush(this.#rawBuffer, TypedArrayPrototypeSubarray(v8Header, 0, 1));
+      this.#rawBufferSize++;
+      this.#pendingPartialV8Header = false;
+    }
+
     while (this.#rawBuffer.length > 0) {
+      const prevBufferLength = this.#rawBuffer.length;
+      const prevBufferSize = this.#rawBufferSize;
       this.#processRawBuffer();
+
+      if (this.#rawBuffer.length === prevBufferLength &&
+          this.#rawBufferSize === prevBufferSize) {
+        const bufferHead = this.#rawBuffer[0];
+        this.addToReport({
+          __proto__: null,
+          type: 'test:stdout',
+          data: {
+            __proto__: null,
+            file: this.name,
+            message: StringFromCharCode(bufferHead[0]),
+          },
+        });
+
+        if (TypedArrayPrototypeGetLength(bufferHead) === 1) {
+          ArrayPrototypeShift(this.#rawBuffer);
+        } else {
+          this.#rawBuffer[0] = TypedArrayPrototypeSubarray(bufferHead, 1);
+        }
+        this.#rawBufferSize--;
+      }
     }
   }
   #processRawBuffer() {
diff --git a/test/parallel/test-runner-v8-deserializer.mjs b/test/parallel/test-runner-v8-deserializer.mjs
@@ -14,12 +14,29 @@ async function toArray(chunks) {
   return arr;
 }
 
-const chunks = await toArray(serializer([
-  { type: 'test:diagnostic', data: { nesting: 0, details: {}, message: 'diagnostic' } },
-]));
+const diagnosticEvent = {
+  type: 'test:diagnostic',
+  data: { nesting: 0, details: {}, message: 'diagnostic' },
+};
+const chunks = await toArray(serializer([diagnosticEvent]));
 const defaultSerializer = new DefaultSerializer();
 defaultSerializer.writeHeader();
 const headerLength = defaultSerializer.releaseBuffer().length;
+const headerOnly = Buffer.from([0xff, 0x0f]);
+const oversizedLengthHeader = Buffer.from([0xff, 0x0f, 0x7f, 0xff, 0xff, 0xff]);
+const truncatedLengthHeader = Buffer.from([0xff, 0x0f, 0x00, 0x01, 0x00, 0x00]);
+// Expected stdout for oversizedLengthHeader: first byte is emitted via
+// String.fromCharCode (byte-by-byte fallback in #drainRawBuffer), remaining
+// bytes go through the nonSerialized UTF-8 decode path in #processRawBuffer.
+const oversizedLengthStdout = String.fromCharCode(oversizedLengthHeader[0]) +
+  Buffer.from(oversizedLengthHeader.subarray(1)).toString('utf-8');
+
+function collectStdout(reported) {
+  return reported
+    .filter((event) => event.type === 'test:stdout')
+    .map((event) => event.data.message)
+    .join('');
+}
 
 describe('v8 deserializer', common.mustCall(() => {
   let fileTest;
@@ -56,35 +73,86 @@ describe('v8 deserializer', common.mustCall(() => {
 
   it('should deserialize a serialized chunk', async () => {
     const reported = await collectReported(chunks);
-    assert.deepStrictEqual(reported, [
-      { data: { nesting: 0, details: {}, message: 'diagnostic' }, type: 'test:diagnostic' },
-    ]);
+    assert.deepStrictEqual(reported, [diagnosticEvent]);
   });
 
   it('should deserialize a serialized chunk after non-serialized chunk', async () => {
     const reported = await collectReported([Buffer.concat([Buffer.from('unknown'), ...chunks])]);
     assert.deepStrictEqual(reported, [
       { data: { __proto__: null, file: 'filetest', message: 'unknown' }, type: 'test:stdout' },
-      { data: { nesting: 0, details: {}, message: 'diagnostic' }, type: 'test:diagnostic' },
+      diagnosticEvent,
     ]);
   });
 
   it('should deserialize a serialized chunk before non-serialized output', async () => {
     const reported = await collectReported([Buffer.concat([ ...chunks, Buffer.from('unknown')])]);
     assert.deepStrictEqual(reported, [
-      { data: { nesting: 0, details: {}, message: 'diagnostic' }, type: 'test:diagnostic' },
+      diagnosticEvent,
       { data: { __proto__: null, file: 'filetest', message: 'unknown' }, type: 'test:stdout' },
     ]);
   });
 
+  it('should not hang when buffer starts with v8Header followed by oversized length', async () => {
+    // Regression test for https://github.com/nodejs/node/issues/62693
+    // FF 0F is the v8 serializer header; the next 4 bytes are read as a
+    // big-endian message size.  0x7FFFFFFF far exceeds any actual buffer
+    // size, causing #processRawBuffer to make no progress and
+    // #drainRawBuffer to loop forever without the no-progress guard.
+    const reported = await collectReported([oversizedLengthHeader]);
+    assert.partialDeepStrictEqual(
+      reported,
+      Array.from({ length: reported.length }, () => ({ type: 'test:stdout' })),
+    );
+    assert.strictEqual(collectStdout(reported), oversizedLengthStdout);
+  });
+
+  it('should flush incomplete v8 frame as stdout and keep prior valid data', async () => {
+    // A valid non-serialized message followed by bytes that look like
+    // a v8 header with a truncated/oversized length.
+    const reported = await collectReported([
+      Buffer.from('hello'),
+      truncatedLengthHeader,
+    ]);
+    assert.strictEqual(collectStdout(reported), `hello${truncatedLengthHeader.toString('latin1')}`);
+  });
+
+  it('should flush v8Header-only bytes as stdout when stream ends', async () => {
+    // Just the two-byte v8 header with no size field at all.
+    const reported = await collectReported([headerOnly]);
+    assert(reported.every((event) => event.type === 'test:stdout'));
+    assert.strictEqual(collectStdout(reported), headerOnly.toString('latin1'));
+  });
+
+  it('should resync and parse valid messages after false v8 header', async () => {
+    // A false v8 header (FF 0F + oversized length) followed by a
+    // legitimate serialized message. The parser must skip the corrupt
+    // bytes and still deserialize the real message.
+    const reported = await collectReported([
+      oversizedLengthHeader,
+      ...chunks,
+    ]);
+    assert.deepStrictEqual(reported.at(-1), diagnosticEvent);
+    assert.strictEqual(reported.filter((event) => event.type === 'test:diagnostic').length, 1);
+    assert.strictEqual(collectStdout(reported), oversizedLengthStdout);
+  });
+
+  it('should preserve a false v8 header split across chunks', async () => {
+    const reported = await collectReported([
+      oversizedLengthHeader.subarray(0, 1),
+      oversizedLengthHeader.subarray(1),
+    ]);
+    assert(reported.every((event) => event.type === 'test:stdout'));
+    assert.strictEqual(collectStdout(reported), oversizedLengthStdout);
+  });
+
   const headerPosition = headerLength * 2 + 4;
   for (let i = 0; i < headerPosition + 5; i++) {
     const message = `should deserialize a serialized message split into two chunks {...${i},${i + 1}...}`;
     it(message, async () => {
       const data = chunks[0];
       const reported = await collectReported([data.subarray(0, i), data.subarray(i)]);
       assert.deepStrictEqual(reported, [
-        { data: { nesting: 0, details: {}, message: 'diagnostic' }, type: 'test:diagnostic' },
+        diagnosticEvent,
       ]);
     });
 
@@ -96,7 +164,7 @@ describe('v8 deserializer', common.mustCall(() => {
       ]);
       assert.deepStrictEqual(reported, [
         { data: { __proto__: null, file: 'filetest', message: 'unknown' }, type: 'test:stdout' },
-        { data: { nesting: 0, details: {}, message: 'diagnostic' }, type: 'test:diagnostic' },
+        diagnosticEvent,
         { data: { __proto__: null, file: 'filetest', message: 'unknown' }, type: 'test:stdout' },
       ]);
     }
