// Copyright 2018 The Fuchsia 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 <lib/fidl/cpp/message_buffer.h> #include <zircon/assert.h> #include <stdlib.h> namespace fidl { namespace { uint64_t AddPadding(uint32_t offset) { constexpr uint32_t kMask = alignof(zx_handle_t) - 1; // Cast before addition to avoid overflow. return static_cast<uint64_t>(offset) + static_cast<uint64_t>(offset & kMask); } size_t GetAllocSize(uint32_t bytes_capacity, uint32_t handles_capacity) { return AddPadding(bytes_capacity) + sizeof(zx_handle_t) * handles_capacity; } } // namespace MessageBuffer::MessageBuffer(uint32_t bytes_capacity, uint32_t handles_capacity) : buffer_(static_cast<uint8_t*>(malloc(GetAllocSize(bytes_capacity, handles_capacity)))), bytes_capacity_(bytes_capacity), handles_capacity_(handles_capacity) { ZX_ASSERT_MSG(buffer_, "malloc returned NULL in MessageBuffer::MessageBuffer()"); } MessageBuffer::~MessageBuffer() { free(buffer_); } zx_handle_t* MessageBuffer::handles() const { return reinterpret_cast<zx_handle_t*>(buffer_ + AddPadding(bytes_capacity_)); } Message MessageBuffer::CreateEmptyMessage() { return Message(BytePart(bytes(), bytes_capacity()), HandlePart(handles(), handles_capacity())); } Builder MessageBuffer::CreateBuilder() { return Builder(bytes(), bytes_capacity()); } } // namespace fidl