Function gjs_decode_from_uint8array

gjs/text-encoding.cpp:269–361

decode() function implementation

// decode() function implementation
JSString* gjs_decode_from_uint8array(JSContext* cx, JS::HandleObject byte_array,
                                     const char* encoding,
                                     GjsStringTermination string_termination,
                                     bool fatal) {
    g_assert(encoding && "encoding must be non-null");

    if (!JS_IsUint8Array(byte_array)) {
        gjs_throw(cx, "Argument to decode() must be a Uint8Array");
        return nullptr;
    }

    uint8_t* data;
    size_t len;
    bool is_shared_memory;
    js::GetUint8ArrayLengthAndData(byte_array, &len, &is_shared_memory, &data);

    // If the desired behavior is zero-terminated, calculate the
    // zero-terminated length of the given data.
    if (len && string_termination == GjsStringTermination::ZERO_TERMINATED)
        len = zero_terminated_length(data, len);

    // If the calculated length is 0 we can just return an empty string.
    if (len == 0)
        return JS_GetEmptyString(cx);

    // Optimization, only use glib's iconv-based converters if we're dealing
    // with a non-UTF8 encoding. SpiderMonkey has highly optimized UTF-8 decoder
    // and encoders.
    bool encoding_is_utf8 = is_utf8_label(encoding);
    if (!encoding_is_utf8)
        return gjs_decode_from_uint8array_slow(cx, data, len, encoding, fatal);

    JS::RootedString decoded(cx);
    if (!fatal) {
        decoded.set(gjs_lossy_string_from_utf8_n(
            cx, reinterpret_cast<char*>(data), len));
    } else {
        JS::UTF8Chars chars(reinterpret_cast<char*>(data), len);
        JS::RootedString str(cx, JS_NewStringCopyUTF8N(cx, chars));

        // If an exception occurred, we need to check if the
        // exception was an InternalError. Unfortunately,
        // SpiderMonkey's decoder can throw InternalError for some
        // invalid UTF-8 sources, we have to convert this into a
        // TypeError to match the Encoding specification.
        if (str) {
            decoded.set(str);
        } else {
            JS::RootedValue exc(cx);
            if (!JS_GetPendingException(cx, &exc) || !exc.isObject())
                return nullptr;

            JS::RootedObject exc_obj(cx, &exc.toObject());
            const JSClass* internal_error =
                js::ProtoKeyToClass(JSProto_InternalError);
            if (JS_InstanceOf(cx, exc_obj, internal_error, nullptr)) {
                // Clear the existing exception.
                JS_ClearPendingException(cx);