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
|
/*
* Copyright (C) 2013 Internet Systems Consortium, Inc. ("ISC")
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#include <windows.h>
#include <stdio.h>
#include <io.h>
#include "pread.h"
static CRITICAL_SECTION preadsc;
/* http://stackoverflow.com/a/2390626/1392778 */
#ifdef _MSC_VER
#pragma section(".CRT$XCU",read)
#define INITIALIZER(f) \
static void __cdecl f(void); \
__declspec(allocate(".CRT$XCU")) void(__cdecl * f ## _) (void) = f; \
static void __cdecl f(void)
#elif defined(__GNUC__)
#define INITIALIZER(f) \
static void f(void) __attribute__((constructor)); \
static void f(void)
#endif
#ifdef _WIN64
int pread(int fd, void *buf, unsigned int nbyte, __int64 offset)
{
int cc = -1;
__int64 prev = (__int64) - 1L;
EnterCriticalSection(&preadsc);
prev = _lseeki64(fd, 0L, SEEK_CUR);
if (prev == (__int64) - 1L) {
goto done;
}
if (_lseeki64(fd, offset, SEEK_SET) != offset) {
goto done;
}
cc = _read(fd, buf, nbyte);
done:
if (prev != (__int64) - 1L) {
(void)_lseeki64(fd, prev, SEEK_SET);
}
LeaveCriticalSection(&preadsc);
return cc;
}
#else
int pread(int fd, void *buf, unsigned int nbyte, long offset)
{
int cc = -1;
long prev = -1L;
EnterCriticalSection(&preadsc);
prev = _lseek(fd, 0L, SEEK_CUR);
if (prev == -1L) {
goto done;
}
if (_lseek(fd, offset, SEEK_SET) != offset) {
goto done;
}
cc = _read(fd, buf, nbyte);
done:
if (prev != -1L) {
(void)_lseek(fd, prev, SEEK_SET);
}
LeaveCriticalSection(&preadsc);
return cc;
}
#endif
static void deinitialize(void)
{
DeleteCriticalSection(&preadsc);
}
INITIALIZER(initialize){
InitializeCriticalSection(&preadsc);
atexit(deinitialize);
}
|
