xref: /openbsd-src/lib/libc/stdio/fwrite.c (revision 33b4f39fbeffad07bc3206f173cff9f3c9901cd1)
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)
34 static char rcsid[] = "$OpenBSD: fwrite.c,v 1.3 2003/06/02 20:18:37 millert Exp $";
35 #endif /* LIBC_SCCS and not lint */
36 
37 #include <stdio.h>
38 #include "local.h"
39 #include "fvwrite.h"
40 
41 /*
42  * Write `count' objects (each size `size') from memory to the given file.
43  * Return the number of whole objects written.
44  */
45 size_t
46 fwrite(buf, size, count, fp)
47 	const void *buf;
48 	size_t size, count;
49 	FILE *fp;
50 {
51 	size_t n;
52 	struct __suio uio;
53 	struct __siov iov;
54 
55 	iov.iov_base = (void *)buf;
56 	uio.uio_resid = iov.iov_len = n = count * size;
57 	uio.uio_iov = &iov;
58 	uio.uio_iovcnt = 1;
59 
60 	/*
61 	 * The usual case is success (__sfvwrite returns 0);
62 	 * skip the divide if this happens, since divides are
63 	 * generally slow and since this occurs whenever size==0.
64 	 */
65 	if (__sfvwrite(fp, &uio) == 0)
66 		return (count);
67 	return ((n - uio.uio_resid) / size);
68 }
69