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
|
/* $OpenBSD: fread.c,v 1.15 2016/09/21 04:38:56 guenther Exp $ */
/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <errno.h>
#include "local.h"
#define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 4))
size_t
fread(void *buf, size_t size, size_t count, FILE *fp)
{
size_t resid;
char *p;
int r;
size_t total;
/*
* Extension: Catch integer overflow
*/
if ((size >= MUL_NO_OVERFLOW || count >= MUL_NO_OVERFLOW) &&
size > 0 && SIZE_MAX / size < count) {
errno = EOVERFLOW;
fp->_flags |= __SERR;
return (0);
}
/*
* ANSI and SUSv2 require a return value of 0 if size or count are 0.
*/
if ((resid = count * size) == 0)
return (0);
FLOCKFILE(fp);
_SET_ORIENTATION(fp, -1);
if (fp->_r < 0)
fp->_r = 0;
total = resid;
p = buf;
if ((fp->_flags & __SNBF) != 0) {
/*
* We know if we're unbuffered that our buffer is empty, so
* we can just read directly. This is much faster than the
* loop below which will perform a series of one byte reads.
*/
while (resid > 0 && (r = (*fp->_read)(fp->_cookie, p, resid)) > 0) {
p += r;
resid -= r;
}
FUNLOCKFILE(fp);
return ((total - resid) / size);
}
while (resid > (r = fp->_r)) {
(void)memcpy(p, fp->_p, r);
fp->_p += r;
/* fp->_r = 0 ... done in __srefill */
p += r;
resid -= r;
if (__srefill(fp)) {
/* no more input: return partial result */
FUNLOCKFILE(fp);
return ((total - resid) / size);
}
}
(void)memcpy(p, fp->_p, resid);
fp->_r -= resid;
fp->_p += resid;
FUNLOCKFILE(fp);
return (count);
}
DEF_STRONG(fread);
|
