Fix Buffer.toString("latin1") and make Buffer.toString("utf16le") faster

Fixes #455
Fixes #1016

2 files changed, 44 insertions, 3 deletions

diff --git a/src/bun.js/bindings/JSBuffer.cpp b/src/bun.js/bindings/JSBuffer.cpp
index 8f9ce2dd2..b3e5f0b4e 100644
--- a/src/bun.js/bindings/JSBuffer.cpp
+++ b/src/bun.js/bindings/JSBuffer.cpp
@@ -1141,14 +1141,28 @@ static inline JSC::EncodedJSValue jsBufferPrototypeFunction_toStringBody(JSC::JS
 
     switch (encoding) {
     case WebCore::BufferEncodingType::latin1: {
-        ret = JSC::JSValue::encode(JSC::jsString(vm, WTF::StringImpl::create(reinterpret_cast<const UChar*>(castedThis->typedVector() + offset), length)));
+        LChar* data = nullptr;
+        auto str = String::createUninitialized(length, data);
+        memcpy(data, reinterpret_cast<const char*>(castedThis->typedVector() + offset), length);
+        ret = JSC::JSValue::encode(JSC::jsString(vm, WTFMove(str)));
         break;
     }
+
+    case WebCore::BufferEncodingType::ucs2:
+    case WebCore::BufferEncodingType::utf16le: {
+        UChar* data = nullptr;
+        size_t u16length = length > 1 ? length / 2 : 1;
+        auto str = String::createUninitialized(u16length, data);
+        // always zero out the last byte of the string incase the buffer is not a multiple of 2
+        data[u16length - 1] = 0;
+        memcpy(data, reinterpret_cast<const char*>(castedThis->typedVector() + offset), length);
+        ret = JSC::JSValue::encode(JSC::jsString(vm, WTFMove(str)));
+        break;
+    }
+
     case WebCore::BufferEncodingType::buffer:
     case WebCore::BufferEncodingType::utf8:
     case WebCore::BufferEncodingType::ascii:
-    case WebCore::BufferEncodingType::ucs2:
-    case WebCore::BufferEncodingType::utf16le:
     case WebCore::BufferEncodingType::base64:
     case WebCore::BufferEncodingType::base64url:
     case WebCore::BufferEncodingType::hex: {
diff --git a/test/bun.js/buffer.test.js b/test/bun.js/buffer.test.js
index 14394bd2a..b8771d5b4 100644
--- a/test/bun.js/buffer.test.js
+++ b/test/bun.js/buffer.test.js
@@ -600,6 +600,33 @@ it("Buffer.from(base64)", () => {
   ).toBe('console.log("hello world")\n');
 });
 
+it("Buffer.toString regessions", () => {
+  expect(
+    Buffer.from([65, 0])
+      .toString("utf16le")
+      .split("")
+      .map((x) => x.charCodeAt(0)),
+  ).toEqual([65]);
+  expect(Buffer.from([65, 0]).toString("base64")).toBe("QQA=");
+  expect(
+    Buffer.from('{"alg":"RS256","typ":"JWT"}', "latin1").toString("latin1"),
+  ).toBe('{"alg":"RS256","typ":"JWT"}');
+  expect(
+    Buffer.from('{"alg":"RS256","typ":"JWT"}', "utf8").toString("utf8"),
+  ).toBe('{"alg":"RS256","typ":"JWT"}');
+});
+
+it("Buffer.toString(utf16le)", () => {
+  const buf = Buffer.from("hello world", "utf16le");
+  expect(buf.toString("utf16le")).toBe("hello world");
+  expect(buf.toString("utf16le", 0, 5)).toBe("he");
+});
+
+it("Buffer.toString(binary)", () => {
+  var x = Buffer.from("<?xm", "binary");
+  expect(x.toString("binary")).toBe("<?xm");
+});
+
 it("Buffer.toString(base64)", () => {
   {
     const buf = Buffer.from("hello world");