1 /* $NetBSD: fread.c,v 1.11 1999/09/16 12:45:34 lukem 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 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93"; 43 #else 44 __RCSID("$NetBSD: fread.c,v 1.11 1999/09/16 12:45:34 lukem Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include <assert.h> 49 #include <errno.h> 50 #include <stdio.h> 51 #include <string.h> 52 #include "local.h" 53 #include "reentrant.h" 54 55 size_t 56 fread(buf, size, count, fp) 57 void *buf; 58 size_t size, count; 59 FILE *fp; 60 { 61 size_t resid; 62 char *p; 63 int r; 64 size_t total; 65 66 if (size == 0 || count == 0) /* check first, according to SUS */ 67 return (0); 68 _DIAGASSERT(buf != NULL); 69 _DIAGASSERT(fp != NULL); 70 #ifdef _DIAGNOSTIC 71 if (buf == NULL) { 72 errno = EFAULT; 73 return (0); 74 } 75 if (fp == NULL) { 76 errno = EBADF; 77 return (0); 78 } 79 #endif 80 81 /* 82 * The ANSI standard requires a return value of 0 for a count 83 * or a size of 0. Peculiarily, it imposes no such requirements 84 * on fwrite; it only requires fread to be broken. 85 */ 86 if ((resid = count * size) == 0) 87 return (0); 88 FLOCKFILE(fp); 89 if (fp->_r < 0) 90 fp->_r = 0; 91 total = resid; 92 p = buf; 93 while (resid > (r = fp->_r)) { 94 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 95 fp->_p += r; 96 /* fp->_r = 0 ... done in __srefill */ 97 p += r; 98 resid -= r; 99 if (__srefill(fp)) { 100 /* no more input: return partial result */ 101 FUNLOCKFILE(fp); 102 return ((total - resid) / size); 103 } 104 } 105 (void)memcpy((void *)p, (void *)fp->_p, resid); 106 fp->_r -= resid; 107 fp->_p += resid; 108 FUNLOCKFILE(fp); 109 return (count); 110 } 111