1 /* $NetBSD: fread.c,v 1.6 1995/02/02 02:09:34 jtc 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 #if defined(LIBC_SCCS) && !defined(lint) 40 #if 0 41 static char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93"; 42 #endif 43 static char rcsid[] = "$NetBSD: fread.c,v 1.6 1995/02/02 02:09:34 jtc Exp $"; 44 #endif /* LIBC_SCCS and not lint */ 45 46 #include <stdio.h> 47 #include <string.h> 48 49 size_t 50 fread(buf, size, count, fp) 51 void *buf; 52 size_t size, count; 53 register FILE *fp; 54 { 55 register size_t resid; 56 register char *p; 57 register int r; 58 size_t total; 59 60 /* 61 * The ANSI standard requires a return value of 0 for a count 62 * or a size of 0. Peculiarily, it imposes no such requirements 63 * on fwrite; it only requires fread to be broken. 64 */ 65 if ((resid = count * size) == 0) 66 return (0); 67 if (fp->_r < 0) 68 fp->_r = 0; 69 total = resid; 70 p = buf; 71 while (resid > (r = fp->_r)) { 72 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 73 fp->_p += r; 74 /* fp->_r = 0 ... done in __srefill */ 75 p += r; 76 resid -= r; 77 if (__srefill(fp)) { 78 /* no more input: return partial result */ 79 return ((total - resid) / size); 80 } 81 } 82 (void)memcpy((void *)p, (void *)fp->_p, resid); 83 fp->_r -= resid; 84 fp->_p += resid; 85 return (count); 86 } 87