| // Copyright 2013 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "gin/array_buffer.h" |
| |
| #include <stddef.h> |
| #include <stdlib.h> |
| |
| #include "base/allocator/partition_allocator/page_allocator.h" |
| #include "base/logging.h" |
| #include "base/partition_alloc_buildflags.h" |
| #include "build/build_config.h" |
| #include "gin/per_isolate_data.h" |
| |
| #if defined(OS_POSIX) |
| #include <sys/mman.h> |
| |
| #ifndef MAP_ANONYMOUS |
| #define MAP_ANONYMOUS MAP_ANON |
| #endif |
| #endif // defined(OS_POSIX) |
| |
| namespace gin { |
| |
| namespace { |
| |
| gin::WrapperInfo g_array_buffer_wrapper_info = {gin::kEmbedderNativeGin}; |
| |
| } // namespace |
| |
| static_assert(V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT == 2, |
| "array buffers must have two internal fields"); |
| |
| // ArrayBufferAllocator ------------------------------------------------------- |
| |
| void* ArrayBufferAllocator::Allocate(size_t length) { |
| // TODO(bbudge) Use partition allocator for malloc/calloc allocations. |
| return calloc(1, length); |
| } |
| |
| void* ArrayBufferAllocator::AllocateUninitialized(size_t length) { |
| return malloc(length); |
| } |
| |
| void ArrayBufferAllocator::Free(void* data, size_t length) { |
| free(data); |
| } |
| |
| ArrayBufferAllocator* ArrayBufferAllocator::SharedInstance() { |
| static ArrayBufferAllocator* instance = new ArrayBufferAllocator(); |
| return instance; |
| } |
| |
| // ArrayBuffer::Private ------------------------------------------------------- |
| |
| // This class exists to solve a tricky lifetime problem. The V8 API doesn't |
| // want to expose a direct view into the memory behind an array buffer because |
| // V8 might deallocate that memory during garbage collection. Instead, the V8 |
| // API forces us to externalize the buffer and take ownership of the memory. |
| // In order to know when to free the memory, we need to figure out both when |
| // we're done with it and when V8 is done with it. |
| // |
| // To determine whether we're done with the memory, every view we have into |
| // the array buffer takes a reference to the ArrayBuffer::Private object that |
| // actually owns the memory. To determine when V8 is done with the memory, we |
| // open a weak handle to the ArrayBuffer object. When we receive the weak |
| // callback, we know the object is about to be garbage collected and we can |
| // drop V8's implied reference to the memory. |
| // |
| // The final subtlety is that we need every ArrayBuffer into the same array |
| // buffer to AddRef the same ArrayBuffer::Private. To make that work, we store |
| // a pointer to the ArrayBuffer::Private object in an internal field of the |
| // ArrayBuffer object. |
| // |
| class ArrayBuffer::Private : public base::RefCounted<ArrayBuffer::Private> { |
| public: |
| static scoped_refptr<Private> From(v8::Isolate* isolate, |
| v8::Local<v8::ArrayBuffer> array); |
| |
| void* buffer() const { return buffer_; } |
| size_t length() const { return length_; } |
| |
| private: |
| friend class base::RefCounted<Private>; |
| |
| Private(v8::Isolate* isolate, v8::Local<v8::ArrayBuffer> array); |
| ~Private(); |
| |
| static void FirstWeakCallback(const v8::WeakCallbackInfo<Private>& data); |
| static void SecondWeakCallback(const v8::WeakCallbackInfo<Private>& data); |
| |
| v8::Global<v8::ArrayBuffer> array_buffer_; |
| scoped_refptr<Private> self_reference_; |
| v8::Isolate* isolate_; |
| void* buffer_; |
| size_t length_; |
| void* allocation_base_; |
| size_t allocation_length_; |
| v8::ArrayBuffer::Allocator::AllocationMode allocation_mode_; |
| }; |
| |
| scoped_refptr<ArrayBuffer::Private> ArrayBuffer::Private::From( |
| v8::Isolate* isolate, v8::Local<v8::ArrayBuffer> array) { |
| if (array->IsExternal()) { |
| CHECK_EQ(WrapperInfo::From(v8::Local<v8::Object>::Cast(array)), |
| &g_array_buffer_wrapper_info) |
| << "Cannot mix blink and gin ArrayBuffers"; |
| return base::WrapRefCounted(static_cast<Private*>( |
| array->GetAlignedPointerFromInternalField(kEncodedValueIndex))); |
| } |
| return base::WrapRefCounted(new Private(isolate, array)); |
| } |
| |
| ArrayBuffer::Private::Private(v8::Isolate* isolate, |
| v8::Local<v8::ArrayBuffer> array) |
| : array_buffer_(isolate, array), isolate_(isolate) { |
| // Take ownership of the array buffer. |
| CHECK(!array->IsExternal()); |
| v8::ArrayBuffer::Contents contents = array->Externalize(); |
| // We shouldn't receive large page-allocated array buffers. |
| CHECK_NE(v8::ArrayBuffer::Allocator::AllocationMode::kReservation, |
| contents.AllocationMode()); |
| buffer_ = contents.Data(); |
| length_ = contents.ByteLength(); |
| allocation_base_ = contents.AllocationBase(); |
| allocation_length_ = contents.AllocationLength(); |
| |
| DCHECK(reinterpret_cast<uintptr_t>(allocation_base_) <= |
| reinterpret_cast<uintptr_t>(buffer_)); |
| DCHECK(reinterpret_cast<uintptr_t>(buffer_) + length_ <= |
| reinterpret_cast<uintptr_t>(allocation_base_) + allocation_length_); |
| |
| array->SetAlignedPointerInInternalField(kWrapperInfoIndex, |
| &g_array_buffer_wrapper_info); |
| array->SetAlignedPointerInInternalField(kEncodedValueIndex, this); |
| |
| self_reference_ = this; // Cleared in SecondWeakCallback. |
| array_buffer_.SetWeak(this, FirstWeakCallback, |
| v8::WeakCallbackType::kParameter); |
| } |
| |
| ArrayBuffer::Private::~Private() { |
| PerIsolateData::From(isolate_)->allocator()->Free(allocation_base_, |
| allocation_length_); |
| } |
| |
| void ArrayBuffer::Private::FirstWeakCallback( |
| const v8::WeakCallbackInfo<Private>& data) { |
| Private* parameter = data.GetParameter(); |
| parameter->array_buffer_.Reset(); |
| data.SetSecondPassCallback(SecondWeakCallback); |
| } |
| |
| void ArrayBuffer::Private::SecondWeakCallback( |
| const v8::WeakCallbackInfo<Private>& data) { |
| Private* parameter = data.GetParameter(); |
| parameter->self_reference_ = NULL; |
| } |
| |
| // ArrayBuffer ---------------------------------------------------------------- |
| |
| ArrayBuffer::ArrayBuffer() |
| : bytes_(0), |
| num_bytes_(0) { |
| } |
| |
| ArrayBuffer::ArrayBuffer(v8::Isolate* isolate, |
| v8::Local<v8::ArrayBuffer> array) { |
| private_ = ArrayBuffer::Private::From(isolate, array); |
| bytes_ = private_->buffer(); |
| num_bytes_ = private_->length(); |
| } |
| |
| ArrayBuffer::~ArrayBuffer() = default; |
| |
| ArrayBuffer& ArrayBuffer::operator=(const ArrayBuffer& other) = default; |
| |
| // Converter<ArrayBuffer> ----------------------------------------------------- |
| |
| bool Converter<ArrayBuffer>::FromV8(v8::Isolate* isolate, |
| v8::Local<v8::Value> val, |
| ArrayBuffer* out) { |
| if (!val->IsArrayBuffer()) |
| return false; |
| *out = ArrayBuffer(isolate, v8::Local<v8::ArrayBuffer>::Cast(val)); |
| return true; |
| } |
| |
| // ArrayBufferView ------------------------------------------------------------ |
| |
| ArrayBufferView::ArrayBufferView() |
| : offset_(0), |
| num_bytes_(0) { |
| } |
| |
| ArrayBufferView::ArrayBufferView(v8::Isolate* isolate, |
| v8::Local<v8::ArrayBufferView> view) |
| : array_buffer_(isolate, view->Buffer()), |
| offset_(view->ByteOffset()), |
| num_bytes_(view->ByteLength()) { |
| } |
| |
| ArrayBufferView::~ArrayBufferView() = default; |
| |
| ArrayBufferView& ArrayBufferView::operator=(const ArrayBufferView& other) = |
| default; |
| |
| // Converter<ArrayBufferView> ------------------------------------------------- |
| |
| bool Converter<ArrayBufferView>::FromV8(v8::Isolate* isolate, |
| v8::Local<v8::Value> val, |
| ArrayBufferView* out) { |
| if (!val->IsArrayBufferView()) |
| return false; |
| *out = ArrayBufferView(isolate, v8::Local<v8::ArrayBufferView>::Cast(val)); |
| return true; |
| } |
| |
| } // namespace gin |