1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
|
/*
* This file is part of MPlayer.
*
* MPlayer is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* MPlayer is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with MPlayer; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/**
* \file mmap_anon.c
* \brief Provide a compatible anonymous space mapping function
*/
#include "config.h"
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#if defined(MAP_ANON) && !defined(MAP_ANONYMOUS)
#define MAP_ANONYMOUS MAP_ANON
#endif
/*
* mmap() anonymous space, depending on the system's mmap() style. On systems
* that use the /dev/zero mapping idiom, zerofd will be set to the file descriptor
* of the opened /dev/zero.
*/
/**
* \brief mmap() anonymous space, depending on the system's mmap() style. On systems
* that use the /dev/zero mapping idiom, zerofd will be set to the file descriptor
* of the opened /dev/zero.
*
* \param addr address to map at.
* \param len number of bytes from addr to be mapped.
* \param prot protections (region accessibility).
* \param flags specifies the type of the mapped object.
* \param offset start mapping at byte offset.
* \param zerofd
* \return a pointer to the mapped region upon successful completion, -1 otherwise.
*/
void *mmap_anon(void *addr, size_t len, int prot, int flags, off_t offset)
{
void *result;
/* From loader/ext.c:
* "Linux EINVAL's on us if we don't pass MAP_PRIVATE to an anon mmap"
* Therefore we preserve the same behavior on all platforms, ie. no
* shared mappings of anon space (if the concepts are supported). */
#if defined(MAP_SHARED) && defined(MAP_PRIVATE)
flags = (flags & ~MAP_SHARED) | MAP_PRIVATE;
#endif /* defined(MAP_SHARED) && defined(MAP_PRIVATE) */
#ifdef MAP_ANONYMOUS
/* BSD-style anonymous mapping */
result = mmap(addr, len, prot, flags | MAP_ANONYMOUS, -1, offset);
#else
/* SysV-style anonymous mapping */
int fd;
fd = open("/dev/zero", O_RDWR);
if(fd < 0){
perror( "Cannot open /dev/zero for READ+WRITE. Check permissions! error: ");
return NULL;
}
result = mmap(addr, len, prot, flags, fd, offset);
close(fd);
#endif /* MAP_ANONYMOUS */
return result;
}
|
