stdio/FreeBSD/fwrite.c

   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  * 4. 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 sccsid[] = "@(#)fwrite.c    8.1 (Berkeley) 6/4/93";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/stdio/fwrite.c,v 1.13 2009/07/12 13:09:43 ed Exp $");
  38
  39 #include "namespace.h"
  40 #include <stdio.h>
  41 #include "un-namespace.h"
  42 #include "local.h"
  43 #include "fvwrite.h"
  44 #include "libc_private.h"
  45
  46 /*
  47  * The maximum amount to write to avoid integer overflow (especially for
  48  * uio_resid in struct __suio).  INT_MAX is odd, so it make sense to make it
  49  * even.  We subtract (BUFSIZ - 1) to get a whole number of BUFSIZ chunks.
  50  */
  51 #define MAXWRITE        (INT_MAX - (BUFSIZ - 1))
  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(buf, size, count, fp)
  59         const void * __restrict buf;
  60         size_t size, count;
  61         FILE * __restrict fp;
  62 {
  63         size_t n, resid;
  64         struct __suio uio;
  65         struct __siov iov;
  66         int s;
  67
  68         /*
  69          * ANSI and SUSv2 require a return value of 0 if size or count are 0.
  70          */
  71         n = count * size;
  72 #if __DARWIN_UNIX03
  73         if (n == 0)
  74                 return (0);
  75 #endif
  76         uio.uio_iov = &iov;
  77         uio.uio_iovcnt = 1;
  78
  79         FLOCKFILE(fp);
  80         ORIENT(fp, -1);
  81
  82         for (resid = n; resid > 0; buf += s, resid -= s) {
  83                 s = resid > INT_MAX ? MAXWRITE : (int)resid;
  84                 iov.iov_base = (void *)buf;
  85                 uio.uio_resid = iov.iov_len = s;
  86
  87                 /*
  88                  * The usual case is success (__sfvwrite returns 0);
  89                  * skip the divide if this happens, since divides are
  90                  * generally slow and since this occurs whenever size==0.
  91                  */
  92                 if (__sfvwrite(fp, &uio) != 0) {
  93                         count = (n - resid + s - uio.uio_resid) / size;
  94                         break;
  95                 }
  96         }
  97         FUNLOCKFILE(fp);
  98         return (count);
  99 }