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      1 /*	$NetBSD: fwrite.c,v 1.19 2021/02/01 17:50:53 jdolecek 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. 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 <sys/cdefs.h>
     36 #if defined(LIBC_SCCS) && !defined(lint)
     37 #if 0
     38 static char sccsid[] = "@(#)fwrite.c	8.1 (Berkeley) 6/4/93";
     39 #else
     40 __RCSID("$NetBSD: fwrite.c,v 1.19 2021/02/01 17:50:53 jdolecek Exp $");
     41 #endif
     42 #endif /* LIBC_SCCS and not lint */
     43 
     44 #include <assert.h>
     45 #include <errno.h>
     46 #include <stdio.h>
     47 #include "reentrant.h"
     48 #include "local.h"
     49 #include "fvwrite.h"
     50 
     51 #define MUL_NO_OVERFLOW	(1UL << (sizeof(size_t) * 4))
     52 
     53 /*
     54  * Write `count' objects (each size `size') from memory to the given file.
     55  * Return the number of whole objects written.
     56  */
     57 size_t
     58 fwrite(const void *buf, size_t size, size_t count, FILE *fp)
     59 {
     60 	size_t n;
     61 	struct __suio uio;
     62 	struct __siov iov;
     63 
     64 	/*
     65 	 * Extension:  Catch integer overflow
     66 	 */
     67 	if ((size >= MUL_NO_OVERFLOW || count >= MUL_NO_OVERFLOW) &&
     68 	    size > 0 && count > SIZE_MAX / size) {
     69 		errno = EOVERFLOW;
     70 		fp->_flags |= __SERR;
     71 		return (0);
     72 	}
     73 
     74 	/*
     75 	 * SUSv2 requires a return value of 0 for a count or a size of 0.
     76 	 */
     77 	if ((n = count * size) == 0)
     78 		return 0;
     79 
     80 	iov.iov_base = __UNCONST(buf);
     81 	uio.uio_resid = iov.iov_len = n;
     82 	uio.uio_iov = &iov;
     83 	uio.uio_iovcnt = 1;
     84 
     85 	/*
     86 	 * The usual case is success (__sfvwrite returns 0);
     87 	 * skip the divide if this happens, since divides are
     88 	 * generally slow and since this occurs whenever size==0.
     89 	 */
     90 	FLOCKFILE(fp);
     91 	if (__sfvwrite(fp, &uio) != 0)
     92 		count = ((n - uio.uio_resid) / size);
     93 	FUNLOCKFILE(fp);
     94 	return count;
     95 }
     96