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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2021, Google Inc.
*
* unique_fd.cpp - File descriptor wrapper that owns a file descriptor
*/
#include <libcamera/base/unique_fd.h>
#include <unistd.h>
#include <utility>
#include <libcamera/base/log.h>
/**
* \file base/unique_fd.h
* \brief File descriptor wrapper that owns a file descriptor
*/
namespace libcamera {
LOG_DEFINE_CATEGORY(UniqueFD)
/**
* \class UniqueFD
* \brief unique_ptr-like wrapper for a file descriptor
*
* The UniqueFD is a wrapper that owns and manages the lifetime of a file
* descriptor. It is constructed from a numerical file descriptor, and takes
* over its ownership. The file descriptor is closed when the UniqueFD is
* destroyed, or when it is assigned another file descriptor with operator=()
* or reset().
*/
/**
* \fn UniqueFD::UniqueFD()
* \brief Construct a UniqueFD that owns no file descriptor
*/
/**
* \fn UniqueFD::UniqueFD(int fd)
* \brief Construct a UniqueFD that owns \a fd
* \param[in] fd A file descriptor to manage
*/
/**
* \fn UniqueFD::UniqueFD(UniqueFD &&other)
* \brief Move constructor, create a UniqueFD by taking over \a other
* \param[in] other The other UniqueFD
*
* Create a UniqueFD by transferring ownership of the file descriptor owned by
* \a other. Upon return, the \a other UniqueFD is invalid.
*/
/**
* \fn UniqueFD::~UniqueFD()
* \brief Destroy the UniqueFD instance
*
* If a file descriptor is owned, it is closed.
*/
/**
* \fn UniqueFD::operator=(UniqueFD &&other)
* \brief Move assignment operator, replace a UniqueFD by taking over \a other
* \param[in] other The other UniqueFD
*
* If this UniqueFD owns a file descriptor, the file descriptor is closed
* first. The file descriptor is then replaced by the one of \a other. Upon
* return, \a other is invalid.
*
* \return A reference to this UniqueFD
*/
/**
* \fn UniqueFD::release()
* \brief Release ownership of the file descriptor without closing it
*
* This function releases and returns the owned file descriptor without closing
* it. The caller owns the returned value and must take care of handling its
* life time to avoid file descriptor leakages. Upon return this UniqueFD is
* invalid.
*
* \return The managed file descriptor, or -1 if no file descriptor was owned
*/
/**
* \brief Replace the managed file descriptor
* \param[in] fd The new file descriptor to manage
*
* Close the managed file descriptor, if any, and replace it with the new \a fd.
*
* Self-resetting (passing an \a fd already managed by this instance) is invalid
* and results in undefined behaviour.
*/
void UniqueFD::reset(int fd)
{
ASSERT(!isValid() || fd != fd_);
std::swap(fd, fd_);
if (fd >= 0)
close(fd);
}
/**
* \fn UniqueFD::swap(UniqueFD &other)
* \brief Swap the managed file descriptors with another UniqueFD
* \param[in] other Another UniqueFD to swap the file descriptor with
*/
/**
* \fn UniqueFD::get()
* \brief Retrieve the managed file descriptor
* \return The managed file descriptor, or -1 if no file descriptor is owned
*/
/**
* \fn UniqueFD::isValid()
* \brief Check if the UniqueFD owns a valid file descriptor
* \return True if the UniqueFD owns a valid file descriptor, false otherwise
*/
} /* namespace libcamera */
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