reset string decoder on end (#1782)

2 files changed, 27 insertions, 2 deletions

diff --git a/src/bun.js/bindings/JSStringDecoder.cpp b/src/bun.js/bindings/JSStringDecoder.cpp
index 66f9cb654..ca79e9e1c 100644
--- a/src/bun.js/bindings/JSStringDecoder.cpp
+++ b/src/bun.js/bindings/JSStringDecoder.cpp
@@ -206,9 +206,30 @@ JSC::JSValue JSStringDecoder::write(JSC::VM& vm, JSC::JSGlobalObject* globalObje
     }
 }
 
-JSC::JSValue JSStringDecoder::end(JSC::VM& vm, JSC::JSGlobalObject* globalObject, uint8_t* bufPtr, uint32_t length)
+class ResetScope final {
+public:
+    ResetScope(JSStringDecoder* decoder);
+    ~ResetScope();
+    JSStringDecoder* m_decoder;
+};
+
+ResetScope::ResetScope(JSStringDecoder* decoder)
+{
+    m_decoder = decoder;
+}
+
+ResetScope::~ResetScope()
+{
+    m_decoder->m_lastTotal = 0;
+    m_decoder->m_lastNeed = 0;
+    memset(m_decoder->m_lastChar, 0, 4);
+}
+
+JSC::JSValue
+JSStringDecoder::end(JSC::VM& vm, JSC::JSGlobalObject* globalObject, uint8_t* bufPtr, uint32_t length)
 {
     auto throwScope = DECLARE_THROW_SCOPE(vm);
+    auto resetScope = ResetScope(this);
     switch (m_encoding) {
     case BufferEncodingType::ucs2:
     case BufferEncodingType::utf16le: {
diff --git a/src/bun.js/bindings/JSStringDecoder.h b/src/bun.js/bindings/JSStringDecoder.h
index 299c2fb96..bce1ae05d 100644
--- a/src/bun.js/bindings/JSStringDecoder.h
+++ b/src/bun.js/bindings/JSStringDecoder.h
@@ -11,7 +11,10 @@ class JSStringDecoder : public JSC::JSDestructibleObject {
 
 public:
     JSStringDecoder(JSC::VM& vm, JSC::Structure* structure, BufferEncodingType encoding)
-        : Base(vm, structure), m_lastNeed(0), m_lastTotal(0), m_encoding(encoding)
+        : Base(vm, structure)
+        , m_lastNeed(0)
+        , m_lastTotal(0)
+        , m_encoding(encoding)
     {
     }
 
@@ -108,6 +111,7 @@ public:
     // Must be defined for each specialization class.
     static JSC::EncodedJSValue JSC_HOST_CALL_ATTRIBUTES construct(JSC::JSGlobalObject*, JSC::CallFrame*);
     DECLARE_EXPORT_INFO;
+
 private:
     JSStringDecoderConstructor(JSC::VM& vm, JSC::Structure* structure, JSC::NativeFunction nativeFunction)
         : Base(vm, structure, nativeFunction, nativeFunction)