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
30class scoped_mmap
31{
32public:
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) noexcept
46    : m_mem (rhs.m_mem),
47      m_length (rhs.m_length)
48  {
49    rhs.m_mem = MAP_FAILED;
50    rhs.m_length = 0;
51  }
52
53  DISABLE_COPY_AND_ASSIGN (scoped_mmap);
54
55  ATTRIBUTE_UNUSED_RESULT void *release () noexcept
56  {
57    void *mem = m_mem;
58    m_mem = MAP_FAILED;
59    m_length = 0;
60    return mem;
61  }
62
63  void reset (void *addr, size_t length, int prot, int flags, int fd,
64	      off_t offset) noexcept
65  {
66    destroy ();
67
68    m_length = length;
69    m_mem = mmap (addr, m_length, prot, flags, fd, offset);
70  }
71
72  size_t size () const noexcept { return m_length; }
73  void *get () const noexcept { return m_mem; }
74
75private:
76  void destroy ()
77  {
78    if (m_mem != MAP_FAILED)
79      munmap (m_mem, m_length);
80  }
81
82  void *m_mem;
83  size_t m_length;
84};
85
86/* Map FILENAME in memory.  Throw an error if anything goes wrong.  */
87scoped_mmap mmap_file (const char *filename);
88
89#endif /* HAVE_SYS_MMAN_H */
90
91#endif /* COMMON_SCOPED_MMAP_H */
92