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#if defined(LIBC_SCCS) && !defined(lint)
36static char sccsid[] = "@(#)fread.c	8.2 (Berkeley) 12/11/93";
37#endif /* LIBC_SCCS and not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD$");
40
41#include "namespace.h"
42#include <errno.h>
43#include <stdint.h>
44#include <stdio.h>
45#include <string.h>
46#include "un-namespace.h"
47#include "local.h"
48#include "libc_private.h"
49
50/*
51 * MT-safe version
52 */
53
54size_t
55fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
56{
57	size_t ret;
58
59	FLOCKFILE_CANCELSAFE(fp);
60	ret = __fread(buf, size, count, fp);
61	FUNLOCKFILE_CANCELSAFE();
62	return (ret);
63}
64
65size_t
66__fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
67{
68	size_t resid;
69	char *p;
70	int r;
71	size_t total;
72
73	/*
74	 * ANSI and SUSv2 require a return value of 0 if size or count are 0.
75	 */
76	if ((count == 0) || (size == 0))
77		return (0);
78
79	/*
80	 * Check for integer overflow.  As an optimization, first check that
81	 * at least one of {count, size} is at least 2^16, since if both
82	 * values are less than that, their product can't possible overflow
83	 * (size_t is always at least 32 bits on FreeBSD).
84	 */
85	if (((count | size) > 0xFFFF) &&
86	    (count > SIZE_MAX / size)) {
87		errno = EINVAL;
88		fp->_flags |= __SERR;
89		return (0);
90	}
91
92	/*
93	 * Compute the (now required to not overflow) number of bytes to
94	 * read and actually do the work.
95	 */
96	resid = count * size;
97	ORIENT(fp, -1);
98	if (fp->_r < 0)
99		fp->_r = 0;
100	total = resid;
101	p = buf;
102	while (resid > (r = fp->_r)) {
103		(void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
104		fp->_p += r;
105		/* fp->_r = 0 ... done in __srefill */
106		p += r;
107		resid -= r;
108		if (__srefill(fp)) {
109			/* no more input: return partial result */
110			return ((total - resid) / size);
111		}
112	}
113	(void)memcpy((void *)p, (void *)fp->_p, resid);
114	fp->_r -= resid;
115	fp->_p += resid;
116	return (count);
117}
118
119__weak_reference(__fread, fread_unlocked);
120