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fwrite.c revision 1.13.2.1 
      1 /*	$NetBSD: fwrite.c,v 1.13.2.1 2002/02/06 23:18:47 nathanw Exp $	*/
      2 
      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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #if defined(LIBC_SCCS) && !defined(lint)
     41 #if 0
     42 static char sccsid[] = "@(#)fwrite.c	8.1 (Berkeley) 6/4/93";
     43 #else
     44 __RCSID("$NetBSD: fwrite.c,v 1.13.2.1 2002/02/06 23:18:47 nathanw Exp $");
     45 #endif
     46 #endif /* LIBC_SCCS and not lint */
     47 
     48 #include <assert.h>
     49 #include <errno.h>
     50 #include <stdio.h>
     51 #include "reentrant.h"
     52 #include "local.h"
     53 #include "fvwrite.h"
     54 
     55 /*
     56  * Write `count' objects (each size `size') from memory to the given file.
     57  * Return the number of whole objects written.
     58  */
     59 size_t
     60 fwrite(buf, size, count, fp)
     61 	const void *buf;
     62 	size_t size, count;
     63 	FILE *fp;
     64 {
     65 	size_t n;
     66 	struct __suio uio;
     67 	struct __siov iov;
     68 
     69 	_DIAGASSERT(fp != NULL);
     70 	/*
     71 	 * SUSv2 requires a return value of 0 for a count or a size of 0.
     72 	 */
     73 	if ((n = count * size) == 0)
     74 		return (0);
     75 	_DIAGASSERT(buf != NULL);
     76 
     77 	/* LINTED we don't play with buf */
     78 	iov.iov_base = (void *)buf;
     79 	uio.uio_resid = iov.iov_len = n;
     80 	uio.uio_iov = &iov;
     81 	uio.uio_iovcnt = 1;
     82 
     83 	/*
     84 	 * The usual case is success (__sfvwrite returns 0);
     85 	 * skip the divide if this happens, since divides are
     86 	 * generally slow and since this occurs whenever size==0.
     87 	 */
     88 	FLOCKFILE(fp);
     89 	if (__sfvwrite(fp, &uio) != 0)
     90 		count = ((n - uio.uio_resid) / size);
     91 	FUNLOCKFILE(fp);
     92 	return (count);
     93 }
     94