lib/libc/stdio/fwrite.c

   1 /*      $NetBSD: fwrite.c,v 1.17 2012/03/15 18:22:30 christos 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 1.17 2012/03/15 18:22:30 christos 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 /*
  52  * Write `count' objects (each size `size') from memory to the given file.
  53  * Return the number of whole objects written.
  54  */
  55 size_t
  56 fwrite(const void *buf, size_t size, size_t count, FILE *fp)
  57 {
  58         size_t n;
  59         struct __suio uio;
  60         struct __siov iov;
  61
  62         _DIAGASSERT(fp != NULL);
  63         /*
  64          * SUSv2 requires a return value of 0 for a count or a size of 0.
  65          */
  66         if ((n = count * size) == 0)
  67                 return 0;
  68         _DIAGASSERT(buf != NULL);
  69
  70         iov.iov_base = __UNCONST(buf);
  71         uio.uio_resid = iov.iov_len = n;
  72         uio.uio_iov = &iov;
  73         uio.uio_iovcnt = 1;
  74
  75         /*
  76          * The usual case is success (__sfvwrite returns 0);
  77          * skip the divide if this happens, since divides are
  78          * generally slow and since this occurs whenever size==0.
  79          */
  80         FLOCKFILE(fp);
  81         if (__sfvwrite(fp, &uio) != 0)
  82                 count = ((n - uio.uio_resid) / size);
  83         FUNLOCKFILE(fp);
  84         return count;
  85 }