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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef REMOTING_BASE_TYPED_BUFFER_H_
#define REMOTING_BASE_TYPED_BUFFER_H_
#include <assert.h>
#include <stdint.h>
#include <algorithm>
#include <memory>
#include <type_traits>
namespace remoting {
// A scoper for a variable-length structure such as SID, SECURITY_DESCRIPTOR and
// similar. These structures typically consist of a header followed by variable-
// length data, so the size may not match sizeof(T). The class supports
// move-only semantics and typed buffer getters.
template <typename T>
requires std::is_trivially_destructible_v<T>
class TypedBuffer {
public:
TypedBuffer() = default;
// Creates an instance of the object allocating a buffer of the given size.
constexpr explicit TypedBuffer(uint32_t length) : length_(length) {
if (length_ > 0) {
buffer_ = std::make_unique<uint8_t[]>(length);
}
}
TypedBuffer(TypedBuffer&& rvalue) : TypedBuffer() { Swap(rvalue); }
TypedBuffer(const TypedBuffer&) = delete;
TypedBuffer& operator=(const TypedBuffer&) = delete;
~TypedBuffer() = default;
TypedBuffer& operator=(TypedBuffer&& rvalue) {
Swap(rvalue);
return *this;
}
// Accessors to get the owned buffer.
// operator* and operator-> will assert() if there is no current buffer.
T& operator*() {
assert(buffer_);
return *(reinterpret_cast<T*>(buffer_.get()));
}
T* operator->() {
assert(buffer_);
return reinterpret_cast<T*>(buffer_.get());
}
T* get() { return buffer_ ? reinterpret_cast<T*>(&buffer_[0]) : nullptr; }
// `const` variants of the above.
const T& operator*() const {
assert(buffer_);
return *(reinterpret_cast<const T*>(buffer_.get()));
}
const T* operator->() const {
assert(buffer_);
return reinterpret_cast<const T*>(buffer_.get());
}
const T* get() const {
return buffer_ ? reinterpret_cast<const T*>(&buffer_[0]) : nullptr;
}
uint32_t length() const { return length_; }
explicit operator bool() const { return buffer_.operator bool(); }
// Swap two buffers.
void Swap(TypedBuffer& other) {
std::swap(buffer_, other.buffer_);
std::swap(length_, other.length_);
}
private:
// Points to the owned buffer.
std::unique_ptr<uint8_t[]> buffer_;
// Length of the owned buffer in bytes.
uint32_t length_ = 0;
};
} // namespace remoting
#endif // REMOTING_BASE_TYPED_BUFFER_H_
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