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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char rcsid[] = "$OpenBSD: fread.c,v 1.2 1996/08/19 08:32:44 tholo Exp $"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <stdio.h> 42 #include <string.h> 43 44 size_t 45 fread(buf, size, count, fp) 46 void *buf; 47 size_t size, count; 48 register FILE *fp; 49 { 50 register size_t resid; 51 register char *p; 52 register int r; 53 size_t total; 54 55 /* 56 * The ANSI standard requires a return value of 0 for a count 57 * or a size of 0. Peculiarily, it imposes no such requirements 58 * on fwrite; it only requires fread to be broken. 59 */ 60 if ((resid = count * size) == 0) 61 return (0); 62 if (fp->_r < 0) 63 fp->_r = 0; 64 total = resid; 65 p = buf; 66 while (resid > (r = fp->_r)) { 67 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 68 fp->_p += r; 69 /* fp->_r = 0 ... done in __srefill */ 70 p += r; 71 resid -= r; 72 if (__srefill(fp)) { 73 /* no more input: return partial result */ 74 return ((total - resid) / size); 75 } 76 } 77 (void)memcpy((void *)p, (void *)fp->_p, resid); 78 fp->_r -= resid; 79 fp->_p += resid; 80 return (count); 81 } 82