stdio/FreeBSD/fread.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[] = "@(#)fread.c     8.2 (Berkeley) 12/11/93";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/stdio/fread.c,v 1.16 2009/07/12 13:09:43 ed Exp $");
  38
  39 #include "namespace.h"
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include "un-namespace.h"
  43 #include "local.h"
  44 #include "libc_private.h"
  45
  46 /*
  47  * MT-safe version
  48  */
  49
  50 size_t
  51 fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
  52 {
  53         size_t ret;
  54
  55         FLOCKFILE(fp);
  56         ret = __fread(buf, size, count, fp);
  57         FUNLOCKFILE(fp);
  58         return (ret);
  59 }
  60
  61 size_t
  62 __fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
  63 {
  64         size_t resid;
  65         char *p;
  66         int r;
  67         size_t total;
  68
  69         /*
  70          * ANSI and SUSv2 require a return value of 0 if size or count are 0.
  71          */
  72         if ((resid = count * size) == 0)
  73                 return (0);
  74         ORIENT(fp, -1);
  75         if (fp->_r < 0)
  76                 fp->_r = 0;
  77         total = resid;
  78         p = buf;
  79         while (resid > (r = fp->_r)) {
  80                 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
  81                 fp->_p += r;
  82                 /* fp->_r = 0 ... done in __srefill */
  83                 p += r;
  84                 resid -= r;
  85                 if (__srefill(fp)) {
  86                         /* no more input: return partial result */
  87                         return ((total - resid) / size);
  88                 }
  89         }
  90         (void)memcpy((void *)p, (void *)fp->_p, resid);
  91         fp->_r -= resid;
  92         fp->_p += resid;
  93         return (count);
  94 }