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
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
/*
* Memory Mapping Allocator
* (C) 1999-2010 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/internal/mmap_mem.h>
#include <vector>
#include <cstring>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#ifndef MAP_FAILED
#define MAP_FAILED -1
#endif
namespace Botan {
namespace {
/*
* MemoryMapping_Allocator Exception
*/
class BOTAN_DLL MemoryMapping_Failed : public Exception
{
public:
MemoryMapping_Failed(const std::string& msg) :
Exception("MemoryMapping_Allocator: " + msg) {}
};
}
/*
* Memory Map a File into Memory
*/
void* MemoryMapping_Allocator::alloc_block(size_t n)
{
class TemporaryFile
{
public:
int get_fd() const { return fd; }
TemporaryFile(const std::string& base)
{
const std::string mkstemp_template = base + "XXXXXX";
std::vector<char> filepath(mkstemp_template.begin(),
mkstemp_template.end());
filepath.push_back(0); // add terminating NULL
mode_t old_umask = ::umask(077);
fd = ::mkstemp(&filepath[0]);
::umask(old_umask);
if(fd == -1)
throw MemoryMapping_Failed("Temporary file allocation failed");
if(::unlink(&filepath[0]) != 0)
throw MemoryMapping_Failed("Could not unlink temporary file");
}
~TemporaryFile()
{
/*
* We can safely close here, because post-mmap the file
* will continue to exist until the mmap is unmapped from
* our address space upon deallocation (or process exit).
*/
if(fd != -1 && ::close(fd) == -1)
throw MemoryMapping_Failed("Could not close file");
}
private:
int fd;
};
TemporaryFile file("/tmp/botan_");
if(file.get_fd() == -1)
throw MemoryMapping_Failed("Could not create file");
std::vector<byte> zeros(4096);
size_t remaining = n;
while(remaining)
{
const size_t write_try = std::min(zeros.size(), remaining);
ssize_t wrote_got = ::write(file.get_fd(),
&zeros[0],
write_try);
if(wrote_got == -1 && errno != EINTR)
throw MemoryMapping_Failed("Could not write to file");
remaining -= wrote_got;
}
#ifndef MAP_NOSYNC
#define MAP_NOSYNC 0
#endif
void* ptr = ::mmap(0, n,
PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_NOSYNC,
file.get_fd(), 0);
if(ptr == static_cast<void*>(MAP_FAILED))
throw MemoryMapping_Failed("Could not map file");
return ptr;
}
/*
* Remove a Memory Mapping
*/
void MemoryMapping_Allocator::dealloc_block(void* ptr, size_t n)
{
if(ptr == nullptr)
return;
const byte PATTERNS[] = { 0x00, 0xF5, 0x5A, 0xAF, 0x00 };
// The char* casts are for Solaris, args are void* on most other systems
for(size_t i = 0; i != sizeof(PATTERNS); ++i)
{
std::memset(ptr, PATTERNS[i], n);
if(::msync(static_cast<char*>(ptr), n, MS_SYNC))
throw MemoryMapping_Failed("Sync operation failed");
}
if(::munmap(static_cast<char*>(ptr), n))
throw MemoryMapping_Failed("Could not unmap file");
}
}
|
