1// Copyright 2018 The Fuchsia Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#include <lib/fidl/cpp/message_buffer.h> 6#include <zircon/assert.h> 7 8#include <stdlib.h> 9 10namespace fidl { 11namespace { 12 13uint64_t AddPadding(uint32_t offset) { 14 constexpr uint32_t kMask = alignof(zx_handle_t) - 1; 15 // Cast before addition to avoid overflow. 16 return static_cast<uint64_t>(offset) + static_cast<uint64_t>(offset & kMask); 17} 18 19size_t GetAllocSize(uint32_t bytes_capacity, uint32_t handles_capacity) { 20 return AddPadding(bytes_capacity) + sizeof(zx_handle_t) * handles_capacity; 21} 22 23} // namespace 24 25MessageBuffer::MessageBuffer(uint32_t bytes_capacity, 26 uint32_t handles_capacity) 27 : buffer_(static_cast<uint8_t*>(malloc(GetAllocSize(bytes_capacity, handles_capacity)))), 28 bytes_capacity_(bytes_capacity), 29 handles_capacity_(handles_capacity) { 30 ZX_ASSERT_MSG(buffer_, "malloc returned NULL in MessageBuffer::MessageBuffer()"); 31} 32 33MessageBuffer::~MessageBuffer() { 34 free(buffer_); 35} 36 37zx_handle_t* MessageBuffer::handles() const { 38 return reinterpret_cast<zx_handle_t*>(buffer_ + AddPadding(bytes_capacity_)); 39} 40 41Message MessageBuffer::CreateEmptyMessage() { 42 return Message(BytePart(bytes(), bytes_capacity()), 43 HandlePart(handles(), handles_capacity())); 44} 45 46Builder MessageBuffer::CreateBuilder() { 47 return Builder(bytes(), bytes_capacity()); 48} 49 50} // namespace fidl 51