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