lib/libc/stdio/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  * 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 sccsid[] = "@(#)fwrite.c    8.1 (Berkeley) 6/4/93";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD$");
  38
  39 #include "namespace.h"
  40 #include <errno.h>
  41 #include <stdint.h>
  42 #include <stdio.h>
  43 #include "un-namespace.h"
  44 #include "local.h"
  45 #include "fvwrite.h"
  46 #include "libc_private.h"
  47
  48 /*
  49  * Write `count' objects (each size `size') from memory to the given file.
  50  * Return the number of whole objects written.
  51  */
  52 size_t
  53 fwrite(const void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
  54 {
  55         size_t n;
  56         struct __suio uio;
  57         struct __siov iov;
  58
  59         /*
  60          * ANSI and SUSv2 require a return value of 0 if size or count are 0.
  61          */
  62         if ((count == 0) || (size == 0))
  63                 return (0);
  64
  65         /*
  66          * Check for integer overflow.  As an optimization, first check that
  67          * at least one of {count, size} is at least 2^16, since if both
  68          * values are less than that, their product can't possibly overflow
  69          * (size_t is always at least 32 bits on FreeBSD).
  70          */
  71         if (((count | size) > 0xFFFF) &&
  72             (count > SIZE_MAX / size)) {
  73                 errno = EINVAL;
  74                 fp->_flags |= __SERR;
  75                 return (0);
  76         }
  77
  78         n = count * size;
  79
  80         iov.iov_base = (void *)buf;
  81         uio.uio_resid = iov.iov_len = n;
  82         uio.uio_iov = &iov;
  83         uio.uio_iovcnt = 1;
  84
  85         FLOCKFILE(fp);
  86         ORIENT(fp, -1);
  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 - uio.uio_resid) / size;
  94         FUNLOCKFILE(fp);
  95         return (count);
  96 }