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 1.6 2005/07/23 20:23:06 joerg Exp $ 39 */ 40 41 #include "namespace.h" 42 #include <stdio.h> 43 #include <string.h> 44 #include "un-namespace.h" 45 46 #include "local.h" 47 #include "libc_private.h" 48 #include "priv_stdio.h" 49 50 size_t 51 fread(void *buf, size_t size, size_t count, FILE *fp) 52 { 53 size_t resid; 54 char *p; 55 int r; 56 size_t total; 57 58 /* 59 * The ANSI standard requires a return value of 0 for a count 60 * or a size of 0. Peculiarily, it imposes no such requirements 61 * on fwrite; it only requires fread to be broken. 62 */ 63 if ((resid = count * size) == 0) 64 return (0); 65 FLOCKFILE(fp); 66 if (fp->pub._r < 0) 67 fp->pub._r = 0; 68 total = resid; 69 p = buf; 70 while (resid > (r = fp->pub._r)) { 71 (void)memcpy((void *)p, (void *)fp->pub._p, (size_t)r); 72 fp->pub._p += r; 73 /* fp->_r = 0 ... done in __srefill */ 74 p += r; 75 resid -= r; 76 if (__srefill(fp)) { 77 /* no more input: return partial result */ 78 FUNLOCKFILE(fp); 79 return ((total - resid) / size); 80 } 81 } 82 (void)memcpy((void *)p, (void *)fp->pub._p, resid); 83 fp->pub._r -= resid; 84 fp->pub._p += resid; 85 FUNLOCKFILE(fp); 86 return (count); 87 } 88