1 /*-
2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #if defined(LIBC_SCCS) && !defined(lint)
34 static char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93";
35 #endif /* LIBC_SCCS and not lint */
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD: stable/10/lib/libc/stdio/fread.c 321074 2017-07-17 14:09:34Z kib $");
38
39 #include "namespace.h"
40 #include <errno.h>
41 #include <stdint.h>
42 #include <stdio.h>
43 #include <string.h>
44 #include "un-namespace.h"
45 #include "local.h"
46 #include "libc_private.h"
47
48 /*
49 * MT-safe version
50 */
51
52 size_t
fread(void * __restrict buf,size_t size,size_t count,FILE * __restrict fp)53 fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
54 {
55 size_t ret;
56
57 FLOCKFILE_CANCELSAFE(fp);
58 ret = __fread(buf, size, count, fp);
59 FUNLOCKFILE_CANCELSAFE();
60 return (ret);
61 }
62
63 size_t
__fread(void * __restrict buf,size_t size,size_t count,FILE * __restrict fp)64 __fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
65 {
66 size_t resid;
67 char *p;
68 int r;
69 size_t total;
70
71 /*
72 * ANSI and SUSv2 require a return value of 0 if size or count are 0.
73 */
74 if ((count == 0) || (size == 0))
75 return (0);
76
77 /*
78 * Check for integer overflow. As an optimization, first check that
79 * at least one of {count, size} is at least 2^16, since if both
80 * values are less than that, their product can't possible overflow
81 * (size_t is always at least 32 bits on FreeBSD).
82 */
83 if (((count | size) > 0xFFFF) &&
84 (count > SIZE_MAX / size)) {
85 errno = EINVAL;
86 fp->_flags |= __SERR;
87 return (0);
88 }
89
90 /*
91 * Compute the (now required to not overflow) number of bytes to
92 * read and actually do the work.
93 */
94 resid = count * size;
95 ORIENT(fp, -1);
96 if (fp->_r < 0)
97 fp->_r = 0;
98 total = resid;
99 p = buf;
100 while (resid > (r = fp->_r)) {
101 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
102 fp->_p += r;
103 /* fp->_r = 0 ... done in __srefill */
104 p += r;
105 resid -= r;
106 if (__srefill(fp)) {
107 /* no more input: return partial result */
108 return ((total - resid) / size);
109 }
110 }
111 (void)memcpy((void *)p, (void *)fp->_p, resid);
112 fp->_r -= resid;
113 fp->_p += resid;
114 return (count);
115 }
116