src/common/file-descriptor.hpp

   1 /*
   2  * Copyright (C) 2023 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #ifndef LTTNG_FILE_DESCRIPTOR_HPP
   9 #define LTTNG_FILE_DESCRIPTOR_HPP
  10
  11 #include <common/error.hpp>
  12 #include <common/format.hpp>
  13
  14 #include <algorithm>
  15
  16 #include <unistd.h>
  17
  18 namespace lttng {
  19
  20 /*
  21  * RAII wrapper around a UNIX file descriptor. A file_descriptor's underlying
  22  * file descriptor.
  23  */
  24 class file_descriptor {
  25 public:
  26         file_descriptor()
  27         {
  28         }
  29
  30         explicit file_descriptor(int raw_fd) noexcept : _raw_fd{ raw_fd }
  31         {
  32                 LTTNG_ASSERT(_is_valid_fd(_raw_fd));
  33         }
  34
  35         file_descriptor(const file_descriptor&) = delete;
  36         file_descriptor& operator=(const file_descriptor&) = delete;
  37         file_descriptor& operator=(file_descriptor&& other)
  38         {
  39                 _cleanup();
  40                 std::swap(_raw_fd, other._raw_fd);
  41                 return *this;
  42         }
  43
  44         file_descriptor(file_descriptor&& other) noexcept
  45         {
  46                 std::swap(_raw_fd, other._raw_fd);
  47         }
  48
  49         ~file_descriptor()
  50         {
  51                 _cleanup();
  52         }
  53
  54         int fd() const noexcept
  55         {
  56                 LTTNG_ASSERT(_is_valid_fd(_raw_fd));
  57                 return _raw_fd;
  58         }
  59
  60 private:
  61         static bool _is_valid_fd(int fd)
  62         {
  63                 return fd >= 0;
  64         }
  65
  66         void _cleanup()
  67         {
  68                 if (!_is_valid_fd(_raw_fd)) {
  69                         return;
  70                 }
  71
  72                 const auto ret = ::close(_raw_fd);
  73
  74                 _raw_fd = -1;
  75                 if (ret) {
  76                         PERROR("Failed to close file descriptor: fd=%i", _raw_fd);
  77                 }
  78         }
  79
  80         int _raw_fd = -1;
  81 };
  82
  83 } /* namespace lttng */
  84
  85 #endif /* LTTNG_FILE_DESCRIPTOR_HPP */