1/*	$OpenBSD: fwrite.c,v 1.11 2014/05/01 16:40:36 deraadt Exp $ */
2/*-
3 * Copyright (c) 1990, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Chris Torek.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <stdio.h>
35#include <stdlib.h>
36#include <stdint.h>
37#include <errno.h>
38#include "local.h"
39#include "fvwrite.h"
40
41#define MUL_NO_OVERFLOW	(1UL << (sizeof(size_t) * 4))
42
43/*
44 * Write `count' objects (each size `size') from memory to the given file.
45 * Return the number of whole objects written.
46 */
47size_t
48fwrite(const void *buf, size_t size, size_t count, FILE *fp)
49{
50	size_t n;
51	struct __suio uio;
52	struct __siov iov;
53	int ret;
54
55	/*
56	 * Extension:  Catch integer overflow
57	 */
58	if ((size >= MUL_NO_OVERFLOW || count >= MUL_NO_OVERFLOW) &&
59	    size > 0 && SIZE_MAX / size < count) {
60		errno = EOVERFLOW;
61		fp->_flags |= __SERR;
62		return (0);
63	}
64
65	/*
66	 * ANSI and SUSv2 require a return value of 0 if size or count are 0.
67	 */
68	if ((n = count * size) == 0)
69		return (0);
70
71	iov.iov_base = (void *)buf;
72	uio.uio_resid = iov.iov_len = n;
73	uio.uio_iov = &iov;
74	uio.uio_iovcnt = 1;
75
76	/*
77	 * The usual case is success (__sfvwrite returns 0);
78	 * skip the divide if this happens, since divides are
79	 * generally slow and since this occurs whenever size==0.
80	 */
81	FLOCKFILE(fp);
82	_SET_ORIENTATION(fp, -1);
83	ret = __sfvwrite(fp, &uio);
84	FUNLOCKFILE(fp);
85	if (ret == 0)
86		return (count);
87	return ((n - uio.uio_resid) / size);
88}
89