gdbsupport/scoped_fd.h

   1 /* scoped_fd, automatically close a file descriptor
   2
   3    Copyright (C) 2018-2022 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef COMMON_SCOPED_FD_H
  21 #define COMMON_SCOPED_FD_H
  22
  23 #include <unistd.h>
  24 #include "gdb_file.h"
  25
  26 /* A smart-pointer-like class to automatically close a file descriptor.  */
  27
  28 class scoped_fd
  29 {
  30 public:
  31   explicit scoped_fd (int fd = -1) noexcept : m_fd (fd) {}
  32
  33   scoped_fd (scoped_fd &&other) noexcept
  34     : m_fd (other.m_fd)
  35   {
  36     other.m_fd = -1;
  37   }
  38
  39   ~scoped_fd ()
  40   {
  41     if (m_fd >= 0)
  42       close (m_fd);
  43   }
  44
  45   scoped_fd &operator= (scoped_fd &&other)
  46   {
  47     if (m_fd != other.m_fd)
  48       {
  49         if (m_fd >= 0)
  50           close (m_fd);
  51         m_fd = other.m_fd;
  52         other.m_fd = -1;
  53       }
  54     return *this;
  55   }
  56
  57   DISABLE_COPY_AND_ASSIGN (scoped_fd);
  58
  59   ATTRIBUTE_UNUSED_RESULT int release () noexcept
  60   {
  61     int fd = m_fd;
  62     m_fd = -1;
  63     return fd;
  64   }
  65
  66   /* Like release, but return a gdb_file_up that owns the file
  67      descriptor.  On success, this scoped_fd will be released.  On
  68      failure, return NULL and leave this scoped_fd in possession of
  69      the fd.  */
  70   gdb_file_up to_file (const char *mode) noexcept
  71   {
  72     gdb_file_up result (fdopen (m_fd, mode));
  73     if (result != nullptr)
  74       m_fd = -1;
  75     return result;
  76   }
  77
  78   int get () const noexcept
  79   {
  80     return m_fd;
  81   }
  82
  83 private:
  84   int m_fd;
  85 };
  86
  87 #endif /* COMMON_SCOPED_FD_H */