gdbsupport/scoped_mmap.h

   1 /* scoped_mmap, automatically unmap files
   2
   3    Copyright (C) 2018-2020 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_MMAP_H
  21 #define COMMON_SCOPED_MMAP_H
  22
  23 #ifdef HAVE_SYS_MMAN_H
  24
  25 #include <sys/mman.h>
  26
  27 /* A smart-pointer-like class to mmap() and automatically munmap() a memory
  28    mapping.  */
  29
  30 class scoped_mmap
  31 {
  32 public:
  33   scoped_mmap () noexcept : m_mem (MAP_FAILED), m_length (0) {}
  34   scoped_mmap (void *addr, size_t length, int prot, int flags, int fd,
  35                off_t offset) noexcept : m_length (length)
  36   {
  37     m_mem = mmap (addr, m_length, prot, flags, fd, offset);
  38   }
  39
  40   ~scoped_mmap ()
  41   {
  42     destroy ();
  43   }
  44
  45   scoped_mmap (scoped_mmap &&rhs)
  46   {
  47     destroy ();
  48
  49     m_mem = rhs.m_mem;
  50     m_length = rhs.m_length;
  51
  52     rhs.m_mem = MAP_FAILED;
  53     rhs.m_length = 0;
  54   }
  55
  56   DISABLE_COPY_AND_ASSIGN (scoped_mmap);
  57
  58   ATTRIBUTE_UNUSED_RESULT void *release () noexcept
  59   {
  60     void *mem = m_mem;
  61     m_mem = MAP_FAILED;
  62     m_length = 0;
  63     return mem;
  64   }
  65
  66   void reset (void *addr, size_t length, int prot, int flags, int fd,
  67               off_t offset) noexcept
  68   {
  69     destroy ();
  70
  71     m_length = length;
  72     m_mem = mmap (addr, m_length, prot, flags, fd, offset);
  73   }
  74
  75   size_t size () const noexcept { return m_length; }
  76   void *get () const noexcept { return m_mem; }
  77
  78 private:
  79   void destroy ()
  80   {
  81     if (m_mem != MAP_FAILED)
  82       munmap (m_mem, m_length);
  83   }
  84
  85   void *m_mem;
  86   size_t m_length;
  87 };
  88
  89 /* Map FILENAME in memory.  Throw an error if anything goes wrong.  */
  90 scoped_mmap mmap_file (const char *filename);
  91
  92 #endif /* HAVE_SYS_MMAN_H */
  93
  94 #endif /* COMMON_SCOPED_MMAP_H */