fwrite.c revision 357852 
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)
34static char sccsid[] = "@(#)fwrite.c	8.1 (Berkeley) 6/4/93";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD: stable/11/lib/libc/stdio/fwrite.c 357852 2020-02-13 03:13:29Z kevans $");
38
39#include "namespace.h"
40#include <errno.h>
41#include <stdint.h>
42#include <stdio.h>
43#include "un-namespace.h"
44#include "local.h"
45#include "fvwrite.h"
46#include "libc_private.h"
47
48/*
49 * Write `count' objects (each size `size') from memory to the given file.
50 * Return the number of whole objects written.
51 */
52size_t
53fwrite_unlocked(const void * __restrict buf, size_t size, size_t count,
54    FILE * __restrict fp)
55{
56	size_t n;
57	struct __suio uio;
58	struct __siov iov;
59
60	/*
61	 * ANSI and SUSv2 require a return value of 0 if size or count are 0.
62	 */
63	if ((count == 0) || (size == 0))
64		return (0);
65
66	/*
67	 * Check for integer overflow.  As an optimization, first check that
68	 * at least one of {count, size} is at least 2^16, since if both
69	 * values are less than that, their product can't possibly overflow
70	 * (size_t is always at least 32 bits on FreeBSD).
71	 */
72	if (((count | size) > 0xFFFF) &&
73	    (count > SIZE_MAX / size)) {
74		errno = EINVAL;
75		fp->_flags |= __SERR;
76		return (0);
77	}
78
79	n = count * size;
80
81	iov.iov_base = (void *)buf;
82	uio.uio_resid = iov.iov_len = n;
83	uio.uio_iov = &iov;
84	uio.uio_iovcnt = 1;
85
86	ORIENT(fp, -1);
87	/*
88	 * The usual case is success (__sfvwrite returns 0);
89	 * skip the divide if this happens, since divides are
90	 * generally slow and since this occurs whenever size==0.
91	 */
92	if (__sfvwrite(fp, &uio) != 0)
93	    count = (n - uio.uio_resid) / size;
94	return (count);
95}
96
97size_t
98fwrite(const void * __restrict buf, size_t size, size_t count,
99    FILE * __restrict fp)
100{
101	size_t n;
102
103	FLOCKFILE_CANCELSAFE(fp);
104	n = fwrite_unlocked(buf, size, count, fp);
105	FUNLOCKFILE_CANCELSAFE();
106	return (n);
107}
108