boost/scope/fd_deleter.hpp

0001 /*
0002  * Distributed under the Boost Software License, Version 1.0.
0003  * (See accompanying file LICENSE_1_0.txt or copy at
0004  * https://www.boost.org/LICENSE_1_0.txt)
0005  *
0006  * Copyright (c) 2023 Andrey Semashev
0007  */
0008 /*!
0009  * \file scope/fd_deleter.hpp
0010  *
0011  * This header contains definition of a deleter function object for
0012  * POSIX-like file descriptors for use with \c unique_resource.
0013  */
0014
0015 #ifndef BOOST_SCOPE_FD_DELETER_HPP_INCLUDED_
0016 #define BOOST_SCOPE_FD_DELETER_HPP_INCLUDED_
0017
0018 #include <boost/scope/detail/config.hpp>
0019
0020 #if !defined(BOOST_WINDOWS)
0021 #include <unistd.h>
0022 #if defined(hpux) || defined(_hpux) || defined(__hpux)
0023 #include <cerrno>
0024 #endif
0025 #else // !defined(BOOST_WINDOWS)
0026 #include <io.h>
0027 #endif // !defined(BOOST_WINDOWS)
0028
0029 #include <boost/scope/detail/header.hpp>
0030
0031 #ifdef BOOST_HAS_PRAGMA_ONCE
0032 #pragma once
0033 #endif
0034
0035 namespace boost {
0036 namespace scope {
0037
0038 //! POSIX-like file descriptor deleter
0039 struct fd_deleter
0040 {
0041     using result_type = void;
0042
0043     //! Closes the file descriptor
0044     result_type operator() (int fd) const noexcept
0045     {
0046 #if !defined(BOOST_WINDOWS)
0047 #if defined(hpux) || defined(_hpux) || defined(__hpux)
0048         // Some systems don't close the file descriptor in case if the thread is interrupted by a signal and close(2) returns EINTR.
0049         // Other (most) systems do close the file descriptor even when when close(2) returns EINTR, and attempting to close it
0050         // again could close a different file descriptor that was opened by a different thread.
0051         //
0052         // Future POSIX standards will likely fix this by introducing posix_close (see https://www.austingroupbugs.net/view.php?id=529)
0053         // and prohibiting returning EINTR from close(2), but we still have to support older systems where this new behavior is not available and close(2)
0054         // behaves differently between systems.
0055         int res;
0056         while (true)
0057         {
0058             res = ::close(fd);
0059             if (BOOST_UNLIKELY(res < 0))
0060             {
0061                 int err = errno;
0062                 if (err == EINTR)
0063                     continue;
0064             }
0065
0066             break;
0067         }
0068 #else
0069         ::close(fd);
0070 #endif
0071 #else // !defined(BOOST_WINDOWS)
0072         ::_close(fd);
0073 #endif // !defined(BOOST_WINDOWS)
0074     }
0075 };
0076
0077 } // namespace scope
0078 } // namespace boost
0079
0080 #include <boost/scope/detail/footer.hpp>
0081
0082 #endif // BOOST_SCOPE_FD_DELETER_HPP_INCLUDED_