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
48size_t
49fread(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
59size_t
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