1 /* $OpenBSD: fread.c,v 1.6 2005/08/08 08:05:36 espie Exp $ */ 2 /*- 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Chris Torek. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <stdio.h> 35 #include <string.h> 36 #include <errno.h> 37 #include "local.h" 38 39 static int 40 lflush(FILE *fp) 41 { 42 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) 43 return (__sflush_locked(fp)); 44 return (0); 45 } 46 47 size_t 48 fread(void *buf, size_t size, size_t count, FILE *fp) 49 { 50 size_t resid; 51 char *p; 52 int r; 53 size_t total; 54 55 /* 56 * The ANSI standard requires a return value of 0 for a count 57 * or a size of 0. Peculiarily, it imposes no such requirements 58 * on fwrite; it only requires fread to be broken. 59 */ 60 if ((resid = count * size) == 0) 61 return (0); 62 FLOCKFILE(fp); 63 if (fp->_r < 0) 64 fp->_r = 0; 65 total = resid; 66 p = buf; 67 68 #if 1 /* BIONIC: optimize unbuffered reads */ 69 if (fp->_flags & __SNBF && fp->_ur == 0) 70 { 71 /* the following comes mainly from __srefill(), with slight 72 * modifications 73 */ 74 75 /* make sure stdio is set up */ 76 if (!__sdidinit) 77 __sinit(); 78 79 fp->_r = 0; /* largely a convenience for callers */ 80 81 /* SysV does not make this test; take it out for compatibility */ 82 if (fp->_flags & __SEOF) { 83 FUNLOCKFILE(fp); 84 return (EOF); 85 } 86 87 /* if not already reading, have to be reading and writing */ 88 if ((fp->_flags & __SRD) == 0) { 89 if ((fp->_flags & __SRW) == 0) { 90 fp->_flags |= __SERR; 91 FUNLOCKFILE(fp); 92 errno = EBADF; 93 return (EOF); 94 } 95 /* switch to reading */ 96 if (fp->_flags & __SWR) { 97 if (__sflush(fp)) { 98 FUNLOCKFILE(fp); 99 return (EOF); 100 } 101 fp->_flags &= ~__SWR; 102 fp->_w = 0; 103 fp->_lbfsize = 0; 104 } 105 fp->_flags |= __SRD; 106 } else { 107 /* 108 * We were reading. If there is an ungetc buffer, 109 * we must have been reading from that. Drop it, 110 * restoring the previous buffer (if any). If there 111 * is anything in that buffer, return. 112 */ 113 if (HASUB(fp)) { 114 FREEUB(fp); 115 } 116 } 117 118 /* 119 * Before reading from a line buffered or unbuffered file, 120 * flush all line buffered output files, per the ANSI C 121 * standard. 122 */ 123 124 if (fp->_flags & (__SLBF|__SNBF)) { 125 /* Ignore this file in _fwalk to deadlock. */ 126 fp->_flags |= __SIGN; 127 (void) _fwalk(lflush); 128 fp->_flags &= ~__SIGN; 129 130 /* Now flush this file without locking it. */ 131 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) 132 __sflush(fp); 133 } 134 135 while (resid > 0) { 136 int len = (*fp->_read)(fp->_cookie, p, resid ); 137 fp->_flags &= ~__SMOD; 138 if (len <= 0) { 139 if (len == 0) 140 fp->_flags |= __SEOF; 141 else { 142 fp->_flags |= __SERR; 143 } 144 FUNLOCKFILE(fp); 145 return ((total - resid) / size); 146 } 147 p += len; 148 resid -= len; 149 } 150 FUNLOCKFILE(fp); 151 return (count); 152 } 153 else 154 #endif 155 { 156 while (resid > (size_t)(r = fp->_r)) { 157 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 158 fp->_p += r; 159 /* fp->_r = 0 ... done in __srefill */ 160 p += r; 161 resid -= r; 162 if (__srefill(fp)) { 163 /* no more input: return partial result */ 164 FUNLOCKFILE(fp); 165 return ((total - resid) / size); 166 } 167 } 168 } 169 170 (void)memcpy((void *)p, (void *)fp->_p, resid); 171 fp->_r -= resid; 172 fp->_p += resid; 173 FUNLOCKFILE(fp); 174 return (count); 175 } 176
