1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include "namespace.h"
36 #include <errno.h>
37 #include <stdint.h>
38 #include <stdio.h>
39 #include <string.h>
40 #include "un-namespace.h"
41 #include "local.h"
42 #include "libc_private.h"
43
44 /*
45 * MT-safe version
46 */
47
48 size_t
fread(void * __restrict buf,size_t size,size_t count,FILE * __restrict fp)49 fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
50 {
51 size_t ret;
52
53 FLOCKFILE_CANCELSAFE(fp);
54 ret = __fread(buf, size, count, fp);
55 FUNLOCKFILE_CANCELSAFE();
56 return (ret);
57 }
58
59 size_t
__fread(void * __restrict buf,size_t size,size_t count,FILE * __restrict fp)60 __fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
61 {
62 size_t resid;
63 char *p;
64 int r;
65 size_t total;
66
67 /*
68 * ANSI and SUSv2 require a return value of 0 if size or count are 0.
69 */
70 if ((count == 0) || (size == 0))
71 return (0);
72
73 /*
74 * Check for integer overflow. As an optimization, first check that
75 * at least one of {count, size} is at least 2^16, since if both
76 * values are less than that, their product can't possible overflow
77 * (size_t is always at least 32 bits on FreeBSD).
78 */
79 if (((count | size) > 0xFFFF) &&
80 (count > SIZE_MAX / size)) {
81 errno = EINVAL;
82 fp->_flags |= __SERR;
83 return (0);
84 }
85
86 /*
87 * Compute the (now required to not overflow) number of bytes to
88 * read and actually do the work.
89 */
90 resid = count * size;
91 ORIENT(fp, -1);
92 if (fp->_r < 0)
93 fp->_r = 0;
94 total = resid;
95 p = buf;
96
97 /*
98 * If we're unbuffered we know that the buffer in fp is empty so
99 * we can read directly into buf. This is much faster than a
100 * series of one byte reads into fp->_nbuf.
101 */
102 if ((fp->_flags & __SNBF) != 0 && buf != NULL) {
103 while (resid > 0) {
104 /* set up the buffer */
105 fp->_bf._base = fp->_p = p;
106 fp->_bf._size = resid;
107
108 if (__srefill(fp)) {
109 /* no more input: return partial result */
110 count = (total - resid) / size;
111 break;
112 }
113 p += fp->_r;
114 resid -= fp->_r;
115 }
116
117 /* restore the old buffer (see __smakebuf) */
118 fp->_bf._base = fp->_p = fp->_nbuf;
119 fp->_bf._size = 1;
120 fp->_r = 0;
121
122 return (count);
123 }
124
125 while (resid > (r = fp->_r)) {
126 if (r != 0) {
127 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
128 fp->_p += r;
129 /* fp->_r = 0 ... done in __srefill */
130 p += r;
131 resid -= r;
132 }
133 if (__srefill(fp)) {
134 /* no more input: return partial result */
135 return ((total - resid) / size);
136 }
137 }
138 (void)memcpy((void *)p, (void *)fp->_p, resid);
139 fp->_r -= resid;
140 fp->_p += resid;
141 return (count);
142 }
143
144 __weak_reference(__fread, fread_unlocked);
145