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// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/modules/encoding/text_decoder_stream.h"
#include <memory>
#include <utility>
#include "third_party/blink/renderer/bindings/core/v8/script_promise.h"
#include "third_party/blink/renderer/bindings/core/v8/script_value.h"
#include "third_party/blink/renderer/bindings/core/v8/to_v8_traits.h"
#include "third_party/blink/renderer/bindings/core/v8/v8_binding_for_core.h"
#include "third_party/blink/renderer/bindings/core/v8/v8_typedefs.h"
#include "third_party/blink/renderer/bindings/core/v8/v8_union_arraybuffer_arraybufferview.h"
#include "third_party/blink/renderer/bindings/modules/v8/v8_text_decoder_options.h"
#include "third_party/blink/renderer/core/streams/transform_stream_default_controller.h"
#include "third_party/blink/renderer/core/streams/transform_stream_transformer.h"
#include "third_party/blink/renderer/core/typed_arrays/dom_array_piece.h"
#include "third_party/blink/renderer/core/typed_arrays/dom_typed_array.h"
#include "third_party/blink/renderer/modules/encoding/encoding.h"
#include "third_party/blink/renderer/platform/bindings/exception_messages.h"
#include "third_party/blink/renderer/platform/bindings/exception_state.h"
#include "third_party/blink/renderer/platform/wtf/text/string_view.h"
#include "third_party/blink/renderer/platform/wtf/text/text_codec.h"
#include "third_party/blink/renderer/platform/wtf/text/text_encoding.h"
#include "third_party/blink/renderer/platform/wtf/text/text_encoding_registry.h"
namespace blink {
class TextDecoderStream::Transformer final : public TransformStreamTransformer {
public:
explicit Transformer(ScriptState* script_state,
WTF::TextEncoding encoding,
bool fatal,
bool ignore_bom)
: decoder_(NewTextCodec(encoding)),
script_state_(script_state),
fatal_(fatal),
ignore_bom_(ignore_bom),
encoding_has_bom_removal_(EncodingHasBomRemoval(encoding)) {}
Transformer(const Transformer&) = delete;
Transformer& operator=(const Transformer&) = delete;
// Implements the type conversion part of the "decode and enqueue a chunk"
// algorithm.
ScriptPromise<IDLUndefined> Transform(
v8::Local<v8::Value> chunk,
TransformStreamDefaultController* controller,
ExceptionState& exception_state) override {
auto* buffer_source = V8BufferSource::Create(script_state_->GetIsolate(),
chunk, exception_state);
if (exception_state.HadException())
return EmptyPromise();
// This implements the "get a copy of the bytes held by the buffer source"
// algorithm (https://webidl.spec.whatwg.org/#dfn-get-buffer-source-copy).
DOMArrayPiece array_piece(buffer_source);
if (array_piece.ByteLength() > std::numeric_limits<uint32_t>::max()) {
exception_state.ThrowRangeError(
"Buffer size exceeds maximum heap object size.");
return EmptyPromise();
}
DecodeAndEnqueue(array_piece.ByteSpan(), WTF::FlushBehavior::kDoNotFlush,
controller, exception_state);
return ToResolvedUndefinedPromise(script_state_.Get());
}
// Implements the "encode and flush" algorithm.
ScriptPromise<IDLUndefined> Flush(
TransformStreamDefaultController* controller,
ExceptionState& exception_state) override {
DecodeAndEnqueue({}, WTF::FlushBehavior::kDataEOF, controller,
exception_state);
return ToResolvedUndefinedPromise(script_state_.Get());
}
ScriptState* GetScriptState() override { return script_state_.Get(); }
void Trace(Visitor* visitor) const override {
visitor->Trace(script_state_);
TransformStreamTransformer::Trace(visitor);
}
private:
// Implements the second part of "decode and enqueue a chunk" as well as the
// "flush and enqueue" algorithm.
void DecodeAndEnqueue(base::span<const uint8_t> data,
WTF::FlushBehavior flush,
TransformStreamDefaultController* controller,
ExceptionState& exception_state) {
const UChar kBOM = 0xFEFF;
bool saw_error = false;
String output_chunk = decoder_->Decode(data, flush, fatal_, saw_error);
if (fatal_ && saw_error) {
exception_state.ThrowTypeError("The encoded data was not valid.");
return;
}
if (output_chunk.empty()) {
return;
}
if (!ignore_bom_ && !bom_seen_) {
bom_seen_ = true;
if (encoding_has_bom_removal_ && output_chunk[0] == kBOM) {
output_chunk.Remove(0);
if (output_chunk.empty()) {
return;
}
}
}
controller->enqueue(
script_state_,
ScriptValue(script_state_->GetIsolate(),
V8String(script_state_->GetIsolate(), output_chunk)),
exception_state);
}
static bool EncodingHasBomRemoval(const WTF::TextEncoding& encoding) {
const AtomicString& name = encoding.GetName();
return name == "UTF-8" || name == "UTF-16LE" || name == "UTF-16BE";
}
std::unique_ptr<WTF::TextCodec> decoder_;
// There is no danger of ScriptState leaking across worlds because a
// TextDecoderStream can only be accessed from the world that created it.
Member<ScriptState> script_state_;
const bool fatal_;
const bool ignore_bom_;
const bool encoding_has_bom_removal_;
bool bom_seen_;
};
TextDecoderStream* TextDecoderStream::Create(ScriptState* script_state,
const String& label,
const TextDecoderOptions* options,
ExceptionState& exception_state) {
WTF::TextEncoding encoding(
label.StripWhiteSpace(&encoding::IsASCIIWhiteSpace));
// The replacement encoding is not valid, but the Encoding API also
// rejects aliases of the replacement encoding.
if (!encoding.IsValid() ||
WTF::EqualIgnoringASCIICase(encoding.GetName(), "replacement")) {
exception_state.ThrowRangeError("The encoding label provided ('" + label +
"') is invalid.");
return nullptr;
}
return MakeGarbageCollected<TextDecoderStream>(script_state, encoding,
options, exception_state);
}
TextDecoderStream::~TextDecoderStream() = default;
String TextDecoderStream::encoding() const {
return encoding_.GetName().GetString().LowerASCII();
}
ReadableStream* TextDecoderStream::readable() const {
return transform_->Readable();
}
WritableStream* TextDecoderStream::writable() const {
return transform_->Writable();
}
void TextDecoderStream::Trace(Visitor* visitor) const {
visitor->Trace(transform_);
ScriptWrappable::Trace(visitor);
}
TextDecoderStream::TextDecoderStream(ScriptState* script_state,
const WTF::TextEncoding& encoding,
const TextDecoderOptions* options,
ExceptionState& exception_state)
: transform_(TransformStream::Create(
script_state,
MakeGarbageCollected<Transformer>(script_state,
encoding,
options->fatal(),
options->ignoreBOM()),
exception_state)),
encoding_(encoding),
fatal_(options->fatal()),
ignore_bom_(options->ignoreBOM()) {}
} // namespace blink
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