1 /* $NetBSD: fread.c,v 1.7 1997/07/13 20:15:03 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93"; 43 #else 44 __RCSID("$NetBSD: fread.c,v 1.7 1997/07/13 20:15:03 christos Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include <stdio.h> 49 #include <string.h> 50 #include "local.h" 51 52 size_t 53 fread(buf, size, count, fp) 54 void *buf; 55 size_t size, count; 56 register FILE *fp; 57 { 58 register size_t resid; 59 register char *p; 60 register int r; 61 size_t total; 62 63 /* 64 * The ANSI standard requires a return value of 0 for a count 65 * or a size of 0. Peculiarily, it imposes no such requirements 66 * on fwrite; it only requires fread to be broken. 67 */ 68 if ((resid = count * size) == 0) 69 return (0); 70 if (fp->_r < 0) 71 fp->_r = 0; 72 total = resid; 73 p = buf; 74 while (resid > (r = fp->_r)) { 75 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 76 fp->_p += r; 77 /* fp->_r = 0 ... done in __srefill */ 78 p += r; 79 resid -= r; 80 if (__srefill(fp)) { 81 /* no more input: return partial result */ 82 return ((total - resid) / size); 83 } 84 } 85 (void)memcpy((void *)p, (void *)fp->_p, resid); 86 fp->_r -= resid; 87 fp->_p += resid; 88 return (count); 89 } 90