/*	$NetBSD: fread.c,v 1.22 2012/03/15 18:22:30 christos Exp $	*/

/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include "reentrant.h"
#include "local.h"

size_t fread(void *buf, size_t size, size_t count, FILE *fp) {
  size_t resid;
  char *p;
  int r;
  size_t total;

  _DIAGASSERT(fp != NULL);
  /*
   * The ANSI standard requires a return value of 0 for a count
   * or a size of 0.  Whilst ANSI imposes no such requirements on
   * fwrite, the SUSv2 does.
   */
  if ((resid = count * size) == 0)
    return 0;

  _DIAGASSERT(buf != NULL);

  FLOCKFILE(fp);
  if (fp->_r < 0)
    fp->_r = 0;
  total = resid;
  p = buf;
  while (resid > (size_t)(r = fp->_r)) {
    (void)memcpy(p, fp->_p, (size_t)r);
    fp->_p += r;
    /* fp->_r = 0 ... done in __srefill */
    p += r;
    resid -= r;
    if (__srefill(fp)) {
      /* no more input: return partial result */
      FUNLOCKFILE(fp);
      return (total - resid) / size;
    }
  }
  (void)memcpy(p, fp->_p, resid);

  _DIAGASSERT(__type_fit(int, fp->_r - resid));
  fp->_r -= (int)resid;
  fp->_p += resid;
  FUNLOCKFILE(fp);
  return count;
}
