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// 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 "mojo/system/message_in_transit.h"
#include <stdlib.h>
#include <string.h>
#include <new>
#include "base/basictypes.h"
#include "base/logging.h"
#include "build/build_config.h"
#include "mojo/system/limits.h"
namespace mojo {
namespace system {
// Avoid dangerous situations, but making sure that the size of the "header" +
// the size of the data fits into a 31-bit number.
COMPILE_ASSERT(static_cast<uint64_t>(sizeof(MessageInTransit)) +
kMaxMessageNumBytes <= 0x7fffffff,
kMaxMessageNumBytes_too_big);
COMPILE_ASSERT(sizeof(MessageInTransit) %
MessageInTransit::kMessageAlignment == 0,
sizeof_MessageInTransit_not_a_multiple_of_alignment);
// C++ requires that storage be declared (in a single compilation unit), but
// MSVS isn't standards-conformant and doesn't handle this correctly.
#if !defined(COMPILER_MSVC)
const size_t MessageInTransit::kMessageAlignment;
#endif
// static
MessageInTransit* MessageInTransit::Create(const void* bytes,
uint32_t num_bytes) {
const size_t size_with_header = sizeof(MessageInTransit) + num_bytes;
const size_t size_with_header_and_padding =
RoundUpMessageAlignment(size_with_header);
char* buffer = static_cast<char*>(malloc(size_with_header_and_padding));
DCHECK_EQ(reinterpret_cast<size_t>(buffer) %
MessageInTransit::kMessageAlignment, 0u);
// The buffer consists of the header (a |MessageInTransit|, constructed using
// a placement new), followed by the data, followed by padding (of zeros).
MessageInTransit* rv = new (buffer) MessageInTransit(num_bytes);
memcpy(buffer + sizeof(MessageInTransit), bytes, num_bytes);
memset(buffer + size_with_header, 0,
size_with_header_and_padding - size_with_header);
return rv;
}
} // namespace system
} // namespace mojo
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