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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char rcsid[] = "$OpenBSD: fread.c,v 1.4 2003/06/02 20:18:37 millert Exp $"; 35 #endif /* LIBC_SCCS and not lint */ 36 37 #include <stdio.h> 38 #include <string.h> 39 #include "local.h" 40 41 size_t 42 fread(buf, size, count, fp) 43 void *buf; 44 size_t size, count; 45 register FILE *fp; 46 { 47 register size_t resid; 48 register char *p; 49 register int r; 50 size_t total; 51 52 /* 53 * The ANSI standard requires a return value of 0 for a count 54 * or a size of 0. Peculiarily, it imposes no such requirements 55 * on fwrite; it only requires fread to be broken. 56 */ 57 if ((resid = count * size) == 0) 58 return (0); 59 if (fp->_r < 0) 60 fp->_r = 0; 61 total = resid; 62 p = buf; 63 while (resid > (r = fp->_r)) { 64 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 65 fp->_p += r; 66 /* fp->_r = 0 ... done in __srefill */ 67 p += r; 68 resid -= r; 69 if (__srefill(fp)) { 70 /* no more input: return partial result */ 71 return ((total - resid) / size); 72 } 73 } 74 (void)memcpy((void *)p, (void *)fp->_p, resid); 75 fp->_r -= resid; 76 fp->_p += resid; 77 return (count); 78 } 79