fread.c revision 35129
1227825Stheraven/*- 2227825Stheraven * Copyright (c) 1990, 1993 3227825Stheraven * The Regents of the University of California. All rights reserved. 4227825Stheraven * 5227825Stheraven * This code is derived from software contributed to Berkeley by 6227825Stheraven * Chris Torek. 7227825Stheraven * 8227825Stheraven * Redistribution and use in source and binary forms, with or without 9227825Stheraven * modification, are permitted provided that the following conditions 10227825Stheraven * are met: 11227825Stheraven * 1. Redistributions of source code must retain the above copyright 12227825Stheraven * notice, this list of conditions and the following disclaimer. 13227825Stheraven * 2. Redistributions in binary form must reproduce the above copyright 14227825Stheraven * notice, this list of conditions and the following disclaimer in the 15227825Stheraven * documentation and/or other materials provided with the distribution. 16227825Stheraven * 3. All advertising materials mentioning features or use of this software 17227825Stheraven * must display the following acknowledgement: 18227825Stheraven * This product includes software developed by the University of 19227825Stheraven * California, Berkeley and its contributors. 20227825Stheraven * 4. Neither the name of the University nor the names of its contributors 21227825Stheraven * may be used to endorse or promote products derived from this software 22227825Stheraven * without specific prior written permission. 23227825Stheraven * 24227825Stheraven * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25227825Stheraven * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26227825Stheraven * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27227825Stheraven * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28227825Stheraven * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29227825Stheraven * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30227825Stheraven * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31227825Stheraven * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32227825Stheraven * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33227825Stheraven * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34227825Stheraven * SUCH DAMAGE. 35227825Stheraven */ 36227825Stheraven 37227825Stheraven#if defined(LIBC_SCCS) && !defined(lint) 38227825Stheraven#if 0 39227825Stheravenstatic char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93"; 40227825Stheraven#endif 41227825Stheravenstatic const char rcsid[] = 42227825Stheraven "$Id: fread.c,v 1.5 1997/02/22 15:02:03 peter Exp $"; 43227825Stheraven#endif /* LIBC_SCCS and not lint */ 44227825Stheraven 45227825Stheraven#include <stdio.h> 46227825Stheraven#include <string.h> 47227825Stheraven#include "local.h" 48227825Stheraven#include "libc_private.h" 49227825Stheraven 50227825Stheravensize_t 51227825Stheravenfread(buf, size, count, fp) 52227825Stheraven void *buf; 53227825Stheraven size_t size, count; 54227825Stheraven register FILE *fp; 55227825Stheraven{ 56227825Stheraven register size_t resid; 57227825Stheraven register char *p; 58227825Stheraven register int r; 59227825Stheraven size_t total; 60227825Stheraven 61227825Stheraven /* 62227825Stheraven * The ANSI standard requires a return value of 0 for a count 63227825Stheraven * or a size of 0. Peculiarily, it imposes no such requirements 64227825Stheraven * on fwrite; it only requires fread to be broken. 65227825Stheraven */ 66227825Stheraven if ((resid = count * size) == 0) 67227825Stheraven return (0); 68227825Stheraven FLOCKFILE(fp); 69227825Stheraven if (fp->_r < 0) 70227825Stheraven fp->_r = 0; 71227825Stheraven total = resid; 72227825Stheraven p = buf; 73227825Stheraven while (resid > (r = fp->_r)) { 74227825Stheraven (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 75227825Stheraven fp->_p += r; 76227825Stheraven /* fp->_r = 0 ... done in __srefill */ 77227825Stheraven p += r; 78227825Stheraven resid -= r; 79227825Stheraven if (__srefill(fp)) { 80227825Stheraven /* no more input: return partial result */ 81227825Stheraven FUNLOCKFILE(fp); 82227825Stheraven return ((total - resid) / size); 83227825Stheraven } 84227825Stheraven } 85227825Stheraven (void)memcpy((void *)p, (void *)fp->_p, resid); 86227825Stheraven fp->_r -= resid; 87227825Stheraven fp->_p += resid; 88227825Stheraven FUNLOCKFILE(fp); 89227825Stheraven return (count); 90227825Stheraven} 91227825Stheraven