1 /* $OpenBSD: fread.c,v 1.12 2014/05/01 16:40:36 deraadt 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 <stdint.h> 37 #include <errno.h> 38 #include "local.h" 39 40 #define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 4)) 41 42 size_t 43 fread(void *buf, size_t size, size_t count, FILE *fp) 44 { 45 size_t resid; 46 char *p; 47 int r; 48 size_t total; 49 50 /* 51 * Extension: Catch integer overflow 52 */ 53 if ((size >= MUL_NO_OVERFLOW || count >= MUL_NO_OVERFLOW) && 54 size > 0 && SIZE_MAX / size < count) { 55 errno = EOVERFLOW; 56 fp->_flags |= __SERR; 57 return (0); 58 } 59 60 /* 61 * ANSI and SUSv2 require a return value of 0 if size or count are 0. 62 */ 63 if ((resid = count * size) == 0) 64 return (0); 65 FLOCKFILE(fp); 66 _SET_ORIENTATION(fp, -1); 67 if (fp->_r < 0) 68 fp->_r = 0; 69 total = resid; 70 p = buf; 71 72 // BEGIN android-added 73 // Avoid pathological behavior on unbuffered files. OpenBSD 74 // will loop reading one byte then memcpying one byte! 75 if ((fp->_flags & __SNBF) != 0) { 76 // We know if we're unbuffered that our buffer is empty, so 77 // we can just read directly. 78 while (resid > 0 && (r = (*fp->_read)(fp->_cookie, p, resid)) > 0) { 79 p += r; 80 resid -= r; 81 } 82 FUNLOCKFILE(fp); 83 return ((total - resid) / size); 84 } 85 // END android-added 86 87 while (resid > (size_t)(r = fp->_r)) { 88 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 89 fp->_p += r; 90 /* fp->_r = 0 ... done in __srefill */ 91 p += r; 92 resid -= r; 93 if (__srefill(fp)) { 94 /* no more input: return partial result */ 95 FUNLOCKFILE(fp); 96 return ((total - resid) / size); 97 } 98 } 99 (void)memcpy((void *)p, (void *)fp->_p, resid); 100 fp->_r -= resid; 101 fp->_p += resid; 102 FUNLOCKFILE(fp); 103 return (count); 104 } 105
