Prex Home / Browse Source - Prex Version: 0.9.0

root/usr/lib/libc/stdio/fread.c

DEFINITIONS

1. fread

   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  */
  33 #include <stdio.h>
  34 #include <string.h>
  35 #include "local.h"
size_t
fread(buf, size, count, fp)
  39         void *buf;
size_t size, count;
FILE *fp;
  42 {
size_t resid;
  44         char *p;
  45         int r;
size_t total;
  48         /*
  49          * The ANSI standard requires a return value of 0 for a count
  50          * or a size of 0.  Peculiarily, it imposes no such requirements
  51          * on fwrite; it only requires fread to be broken.
  52          */
  53         if ((resid = count * size) == 0)
  54                 return (0);
  55         if (fp->_r < 0)
fp->_r = 0;
total = resid;
p = buf;
  59         while (resid > (size_t)(r = fp->_r)) {
  60                 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
fp->_p += r;
  62                 /* fp->_r = 0 ... done in __srefill */
p += r;
resid -= r;
  65                 if (__srefill(fp)) {
  66                         /* no more input: return partial result */
  67                         return ((total - resid) / size);
  68                 }
  69         }
  70         (void)memcpy((void *)p, (void *)fp->_p, resid);
fp->_r -= resid;
fp->_p += resid;
  73         return (count);
  74 }