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// Copyright (c) 2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_UTIL_TOKENPIPE_H
#define BITCOIN_UTIL_TOKENPIPE_H
#ifndef WIN32
#include <cstdint>
#include <optional>
/** One end of a token pipe. */
class TokenPipeEnd
{
private:
int m_fd = -1;
public:
TokenPipeEnd(int fd = -1);
~TokenPipeEnd();
/** Return value constants for TokenWrite and TokenRead. */
enum Status {
TS_ERR = -1, //!< I/O error
TS_EOS = -2, //!< Unexpected end of stream
};
/** Write token to endpoint.
*
* @returns 0 If successful.
* <0 if error:
* TS_ERR If an error happened.
* TS_EOS If end of stream happened.
*/
int TokenWrite(uint8_t token);
/** Read token from endpoint.
*
* @returns >=0 Token value, if successful.
* <0 if error:
* TS_ERR If an error happened.
* TS_EOS If end of stream happened.
*/
int TokenRead();
/** Explicit close function.
*/
void Close();
/** Return whether endpoint is open.
*/
bool IsOpen() { return m_fd != -1; }
// Move-only class.
TokenPipeEnd(TokenPipeEnd&& other)
{
m_fd = other.m_fd;
other.m_fd = -1;
}
TokenPipeEnd& operator=(TokenPipeEnd&& other)
{
Close();
m_fd = other.m_fd;
other.m_fd = -1;
return *this;
}
TokenPipeEnd(const TokenPipeEnd&) = delete;
TokenPipeEnd& operator=(const TokenPipeEnd&) = delete;
};
/** An interprocess or interthread pipe for sending tokens (one-byte values)
* over.
*/
class TokenPipe
{
private:
int m_fds[2] = {-1, -1};
TokenPipe(int fds[2]) : m_fds{fds[0], fds[1]} {}
public:
~TokenPipe();
/** Create a new pipe.
* @returns The created TokenPipe, or an empty std::nullopt in case of error.
*/
static std::optional<TokenPipe> Make();
/** Take the read end of this pipe. This can only be called once,
* as the object will be moved out.
*/
TokenPipeEnd TakeReadEnd();
/** Take the write end of this pipe. This should only be called once,
* as the object will be moved out.
*/
TokenPipeEnd TakeWriteEnd();
/** Close and end of the pipe that hasn't been moved out.
*/
void Close();
// Move-only class.
TokenPipe(TokenPipe&& other)
{
for (int i = 0; i < 2; ++i) {
m_fds[i] = other.m_fds[i];
other.m_fds[i] = -1;
}
}
TokenPipe& operator=(TokenPipe&& other)
{
Close();
for (int i = 0; i < 2; ++i) {
m_fds[i] = other.m_fds[i];
other.m_fds[i] = -1;
}
return *this;
}
TokenPipe(const TokenPipe&) = delete;
TokenPipe& operator=(const TokenPipe&) = delete;
};
#endif // WIN32
#endif // BITCOIN_UTIL_TOKENPIPE_H
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