Fix conversion of QByteArray back to String in JavaScript

Commit 3b7e2a69f7eb8597c807de39b4de39721e9e2bd2 changed behavior so that
QByteArray is converted to the JS ArrayBuffer type, which is a better
fit than QVariant. However ArrayBuffer does not have a toString method
in the spec, and therefore any previous implicit toString conversion
such as when passing to JSON.parse() would fail. To restore
compatibility this patch adds a non-spec toString() that performs an
UTF-8 conversion, as it was done previously through QVariant's toString.

Task-number: QTBUG-55562
Change-Id: I096046954f7b29f7258deaa9ef5c8fa9292552ef
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

1 files changed, 10 insertions, 0 deletions

diff --git a/src/qml/jsruntime/qv4arraybuffer.cpp b/src/qml/jsruntime/qv4arraybuffer.cpp
index e006773c9e..34c7746684 100644
--- a/src/qml/jsruntime/qv4arraybuffer.cpp
+++ b/src/qml/jsruntime/qv4arraybuffer.cpp
@@ -154,6 +154,7 @@ void ArrayBufferPrototype::init(ExecutionEngine *engine, Object *ctor)
     defineDefaultProperty(engine->id_constructor(), (o = ctor));
     defineAccessorProperty(QStringLiteral("byteLength"), method_get_byteLength, 0);
     defineDefaultProperty(QStringLiteral("slice"), method_slice, 2);
+    defineDefaultProperty(QStringLiteral("toString"), method_toString, 0);
 }
 
 ReturnedValue ArrayBufferPrototype::method_get_byteLength(CallContext *ctx)
@@ -198,3 +199,12 @@ ReturnedValue ArrayBufferPrototype::method_slice(CallContext *ctx)
 
     return newBuffer.asReturnedValue();
 }
+
+ReturnedValue ArrayBufferPrototype::method_toString(CallContext *ctx)
+{
+    Scope scope(ctx);
+    Scoped<ArrayBuffer> a(scope, ctx->thisObject());
+    if (!a)
+        return Encode::undefined();
+    return Encode(ctx->engine()->newString(QString::fromUtf8(a->asByteArray())));
+}