1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "namespace.h" 42 #include <errno.h> 43 #include <stdint.h> 44 #include <stdio.h> 45 #include <string.h> 46 #include "un-namespace.h" 47 #include "local.h" 48 #include "libc_private.h" 49 50 /* 51 * MT-safe version 52 */ 53 54 size_t 55 fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp) 56 { 57 size_t ret; 58 59 FLOCKFILE_CANCELSAFE(fp); 60 ret = __fread(buf, size, count, fp); 61 FUNLOCKFILE_CANCELSAFE(); 62 return (ret); 63 } 64 65 size_t 66 __fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp) 67 { 68 size_t resid; 69 char *p; 70 int r; 71 size_t total; 72 73 /* 74 * ANSI and SUSv2 require a return value of 0 if size or count are 0. 75 */ 76 if ((count == 0) || (size == 0)) 77 return (0); 78 79 /* 80 * Check for integer overflow. As an optimization, first check that 81 * at least one of {count, size} is at least 2^16, since if both 82 * values are less than that, their product can't possible overflow 83 * (size_t is always at least 32 bits on FreeBSD). 84 */ 85 if (((count | size) > 0xFFFF) && 86 (count > SIZE_MAX / size)) { 87 errno = EINVAL; 88 fp->_flags |= __SERR; 89 return (0); 90 } 91 92 /* 93 * Compute the (now required to not overflow) number of bytes to 94 * read and actually do the work. 95 */ 96 resid = count * size; 97 ORIENT(fp, -1); 98 if (fp->_r < 0) 99 fp->_r = 0; 100 total = resid; 101 p = buf; 102 103 /* 104 * If we're unbuffered we know that the buffer in fp is empty so 105 * we can read directly into buf. This is much faster than a 106 * series of one byte reads into fp->_nbuf. 107 */ 108 if ((fp->_flags & __SNBF) != 0 && buf != NULL) { 109 while (resid > 0) { 110 /* set up the buffer */ 111 fp->_bf._base = fp->_p = p; 112 fp->_bf._size = resid; 113 114 if (__srefill(fp)) { 115 /* no more input: return partial result */ 116 count = (total - resid) / size; 117 break; 118 } 119 p += fp->_r; 120 resid -= fp->_r; 121 } 122 123 /* restore the old buffer (see __smakebuf) */ 124 fp->_bf._base = fp->_p = fp->_nbuf; 125 fp->_bf._size = 1; 126 fp->_r = 0; 127 128 return (count); 129 } 130 131 while (resid > (r = fp->_r)) { 132 if (r != 0) { 133 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 134 fp->_p += r; 135 /* fp->_r = 0 ... done in __srefill */ 136 p += r; 137 resid -= r; 138 } 139 if (__srefill(fp)) { 140 /* no more input: return partial result */ 141 return ((total - resid) / size); 142 } 143 } 144 (void)memcpy((void *)p, (void *)fp->_p, resid); 145 fp->_r -= resid; 146 fp->_p += resid; 147 return (count); 148 } 149 150 __weak_reference(__fread, fread_unlocked); 151