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85 lines
2.6 KiB
85 lines
2.6 KiB
// Copyright 2014 The Chromium 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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// This file provides a C++ wrapping around the Mojo C API for shared buffers,
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// replacing the prefix of "Mojo" with a "mojo" namespace, and using more
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// strongly-typed representations of |MojoHandle|s.
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//
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// Please see "mojo/public/c/system/buffer.h" for complete documentation of the
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// API.
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#ifndef MOJO_PUBLIC_CPP_SYSTEM_BUFFER_H_
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#define MOJO_PUBLIC_CPP_SYSTEM_BUFFER_H_
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#include <stdint.h>
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#include <memory>
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#include "base/compiler_specific.h"
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#include "base/logging.h"
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#include "mojo/public/c/system/buffer.h"
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#include "mojo/public/cpp/system/handle.h"
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#include "mojo/public/cpp/system/system_export.h"
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namespace mojo {
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namespace internal {
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struct Unmapper {
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void operator()(void* buffer) {
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MojoResult result = MojoUnmapBuffer(buffer);
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DCHECK_EQ(MOJO_RESULT_OK, result);
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}
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};
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} // namespace internal
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using ScopedSharedBufferMapping = std::unique_ptr<void, internal::Unmapper>;
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class SharedBufferHandle;
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typedef ScopedHandleBase<SharedBufferHandle> ScopedSharedBufferHandle;
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// A strongly-typed representation of a |MojoHandle| referring to a shared
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// buffer.
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class MOJO_CPP_SYSTEM_EXPORT SharedBufferHandle : public Handle {
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public:
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enum class AccessMode {
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READ_WRITE,
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READ_ONLY,
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};
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SharedBufferHandle() {}
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explicit SharedBufferHandle(MojoHandle value) : Handle(value) {}
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// Copying and assignment allowed.
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// Creates a new SharedBufferHandle. Returns an invalid handle on failure.
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static ScopedSharedBufferHandle Create(uint64_t num_bytes);
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// Clones this shared buffer handle. If |access_mode| is READ_ONLY or this is
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// a read-only handle, the new handle will be read-only. On failure, this will
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// return an empty result.
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ScopedSharedBufferHandle Clone(AccessMode access_mode) const;
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// Maps |size| bytes of this shared buffer. On failure, this will return a
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// null mapping.
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ScopedSharedBufferMapping Map(uint64_t size) const;
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// Maps |size| bytes of this shared buffer, starting |offset| bytes into the
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// buffer. On failure, this will return a null mapping.
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ScopedSharedBufferMapping MapAtOffset(uint64_t size, uint64_t offset) const;
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// Get the size of this shared buffer.
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uint64_t GetSize() const;
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};
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static_assert(sizeof(SharedBufferHandle) == sizeof(Handle),
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"Bad size for C++ SharedBufferHandle");
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static_assert(sizeof(ScopedSharedBufferHandle) == sizeof(SharedBufferHandle),
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"Bad size for C++ ScopedSharedBufferHandle");
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} // namespace mojo
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#endif // MOJO_PUBLIC_CPP_SYSTEM_BUFFER_H_
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