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// Copyright 2014 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.
// This file provides a C++ wrapping around the Mojo C API for message pipes,
// replacing the prefix of "Mojo" with a "mojo" namespace, and using more
// strongly-typed representations of |MojoHandle|s.
//
// Please see "mojo/public/c/system/message_pipe.h" for complete documentation
// of the API.
#ifndef MOJO_PUBLIC_CPP_SYSTEM_MESSAGE_PIPE_H_
#define MOJO_PUBLIC_CPP_SYSTEM_MESSAGE_PIPE_H_
#include <stdint.h>
#include "base/compiler_specific.h"
#include "base/logging.h"
#include "mojo/public/c/system/message_pipe.h"
#include "mojo/public/cpp/system/handle.h"
#include "mojo/public/cpp/system/macros.h"
namespace mojo {
// A strongly-typed representation of a |MojoHandle| to one end of a message
// pipe.
class MessagePipeHandle : public Handle {
public:
MessagePipeHandle() {}
explicit MessagePipeHandle(MojoHandle value) : Handle(value) {}
// Copying and assignment allowed.
};
static_assert(sizeof(MessagePipeHandle) == sizeof(Handle),
"Bad size for C++ MessagePipeHandle");
typedef ScopedHandleBase<MessagePipeHandle> ScopedMessagePipeHandle;
static_assert(sizeof(ScopedMessagePipeHandle) == sizeof(MessagePipeHandle),
"Bad size for C++ ScopedMessagePipeHandle");
// Creates a message pipe. See |MojoCreateMessagePipe()| for complete
// documentation.
inline MojoResult CreateMessagePipe(const MojoCreateMessagePipeOptions* options,
ScopedMessagePipeHandle* message_pipe0,
ScopedMessagePipeHandle* message_pipe1) {
DCHECK(message_pipe0);
DCHECK(message_pipe1);
MessagePipeHandle handle0;
MessagePipeHandle handle1;
MojoResult rv = MojoCreateMessagePipe(
options, handle0.mutable_value(), handle1.mutable_value());
// Reset even on failure (reduces the chances that a "stale"/incorrect handle
// will be used).
message_pipe0->reset(handle0);
message_pipe1->reset(handle1);
return rv;
}
// The following "...Raw" versions fully expose the underlying API, and don't
// help with ownership of handles (especially when writing messages). It is
// expected that in most cases these methods will be called through generated
// bindings anyway.
// TODO(vtl): Write friendlier versions of these functions (using scoped
// handles and/or vectors) if there is a demonstrated need for them.
// Writes to a message pipe. If handles are attached, on success the handles
// will no longer be valid (the receiver will receive equivalent, but logically
// different, handles). See |MojoWriteMessage()| for complete documentation.
inline MojoResult WriteMessageRaw(MessagePipeHandle message_pipe,
const void* bytes,
uint32_t num_bytes,
const MojoHandle* handles,
uint32_t num_handles,
MojoWriteMessageFlags flags) {
return MojoWriteMessage(
message_pipe.value(), bytes, num_bytes, handles, num_handles, flags);
}
// Reads from a message pipe. See |MojoReadMessage()| for complete
// documentation.
inline MojoResult ReadMessageRaw(MessagePipeHandle message_pipe,
void* bytes,
uint32_t* num_bytes,
MojoHandle* handles,
uint32_t* num_handles,
MojoReadMessageFlags flags) {
return MojoReadMessage(
message_pipe.value(), bytes, num_bytes, handles, num_handles, flags);
}
// A wrapper class that automatically creates a message pipe and owns both
// handles.
class MessagePipe {
public:
MessagePipe();
explicit MessagePipe(const MojoCreateMessagePipeOptions& options);
~MessagePipe();
ScopedMessagePipeHandle handle0;
ScopedMessagePipeHandle handle1;
};
inline MessagePipe::MessagePipe() {
MojoResult result = CreateMessagePipe(nullptr, &handle0, &handle1);
DCHECK_EQ(MOJO_RESULT_OK, result);
}
inline MessagePipe::MessagePipe(const MojoCreateMessagePipeOptions& options) {
MojoResult result = CreateMessagePipe(&options, &handle0, &handle1);
DCHECK_EQ(MOJO_RESULT_OK, result);
}
inline MessagePipe::~MessagePipe() {
}
} // namespace mojo
#endif // MOJO_PUBLIC_CPP_SYSTEM_MESSAGE_PIPE_H_
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