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 * @(#)fread.c 8.2 (Berkeley) 12/11/93 37 * $FreeBSD: src/lib/libc/stdio/fread.c,v 1.7 1999/08/28 00:01:04 peter Exp $ 38 * $DragonFly: src/lib/libc/stdio/fread.c,v 1.5 2005/01/31 22:29:40 dillon Exp $ 39 */ 40 41 #include "namespace.h" 42 #include <stdio.h> 43 #include <string.h> 44 #include "un-namespace.h" 45 #include "local.h" 46 #include "libc_private.h" 47 48 size_t 49 fread(void *buf, size_t size, size_t count, FILE *fp) 50 { 51 size_t resid; 52 char *p; 53 int r; 54 size_t total; 55 56 /* 57 * The ANSI standard requires a return value of 0 for a count 58 * or a size of 0. Peculiarily, it imposes no such requirements 59 * on fwrite; it only requires fread to be broken. 60 */ 61 if ((resid = count * size) == 0) 62 return (0); 63 FLOCKFILE(fp); 64 if (fp->_r < 0) 65 fp->_r = 0; 66 total = resid; 67 p = buf; 68 while (resid > (r = fp->_r)) { 69 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 70 fp->_p += r; 71 /* fp->_r = 0 ... done in __srefill */ 72 p += r; 73 resid -= r; 74 if (__srefill(fp)) { 75 /* no more input: return partial result */ 76 FUNLOCKFILE(fp); 77 return ((total - resid) / size); 78 } 79 } 80 (void)memcpy((void *)p, (void *)fp->_p, resid); 81 fp->_r -= resid; 82 fp->_p += resid; 83 FUNLOCKFILE(fp); 84 return (count); 85 } 86