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

/*-
 * Copyright (c) 1990 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)fread.c     5.4 (Berkeley) 5/4/91";
#endif /* LIBC_SCCS and not lint */

#include <stdio.h>
#include <string.h>

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

        if ((resid = count * size) == 0)
                return (count);
        if (fp->_r < 0)
                fp->_r = 0;
        total = resid;
        p = buf;
        while (resid > (r = fp->_r)) {
                (void) bcopy((void *)fp->_p, (void *)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 */
                        return ((total - resid) / size);
                }
        }
        (void) bcopy((void *)fp->_p, (void *)p, resid);
        fp->_r -= resid;
        fp->_p += resid;
        return (count);
}