// Copyright 2018 The Fuchsia Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include <lib/fidl/cpp/message_buffer.h>
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#include <zircon/assert.h>
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#include <stdlib.h>
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namespace fidl {
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namespace {
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uint64_t AddPadding(uint32_t offset) {
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constexpr uint32_t kMask = alignof(zx_handle_t) - 1;
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// Cast before addition to avoid overflow.
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return static_cast<uint64_t>(offset) + static_cast<uint64_t>(offset & kMask);
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}
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size_t GetAllocSize(uint32_t bytes_capacity, uint32_t handles_capacity) {
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return AddPadding(bytes_capacity) + sizeof(zx_handle_t) * handles_capacity;
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}
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} // namespace
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MessageBuffer::MessageBuffer(uint32_t bytes_capacity,
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uint32_t handles_capacity)
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: buffer_(static_cast<uint8_t*>(malloc(GetAllocSize(bytes_capacity, handles_capacity)))),
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bytes_capacity_(bytes_capacity),
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handles_capacity_(handles_capacity) {
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ZX_ASSERT_MSG(buffer_, "malloc returned NULL in MessageBuffer::MessageBuffer()");
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}
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MessageBuffer::~MessageBuffer() {
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free(buffer_);
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}
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zx_handle_t* MessageBuffer::handles() const {
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return reinterpret_cast<zx_handle_t*>(buffer_ + AddPadding(bytes_capacity_));
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}
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Message MessageBuffer::CreateEmptyMessage() {
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return Message(BytePart(bytes(), bytes_capacity()),
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HandlePart(handles(), handles_capacity()));
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}
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Builder MessageBuffer::CreateBuilder() {
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return Builder(bytes(), bytes_capacity());
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}
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} // namespace fidl
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