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 #include "namespace.h" 40 #include <errno.h> 41 #include <stdint.h> 42 #include <stdio.h> 43 #include <string.h> 44 #include "un-namespace.h" 45 #include "local.h" 46 #include "libc_private.h" 47 48 /* 49 * MT-safe version 50 */ 51 52 size_t 53 fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp) 54 { 55 size_t ret; 56 57 FLOCKFILE_CANCELSAFE(fp); 58 ret = __fread(buf, size, count, fp); 59 FUNLOCKFILE_CANCELSAFE(); 60 return (ret); 61 } 62 63 size_t 64 __fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp) 65 { 66 size_t resid; 67 char *p; 68 int r; 69 size_t total; 70 71 /* 72 * ANSI and SUSv2 require a return value of 0 if size or count are 0. 73 */ 74 if ((count == 0) || (size == 0)) 75 return (0); 76 77 /* 78 * Check for integer overflow. As an optimization, first check that 79 * at least one of {count, size} is at least 2^16, since if both 80 * values are less than that, their product can't possible overflow 81 * (size_t is always at least 32 bits on FreeBSD). 82 */ 83 if (((count | size) > 0xFFFF) && 84 (count > SIZE_MAX / size)) { 85 errno = EINVAL; 86 fp->_flags |= __SERR; 87 return (0); 88 } 89 90 /* 91 * Compute the (now required to not overflow) number of bytes to 92 * read and actually do the work. 93 */ 94 resid = count * size; 95 ORIENT(fp, -1); 96 if (fp->_r < 0) 97 fp->_r = 0; 98 total = resid; 99 p = buf; 100 101 /* 102 * If we're unbuffered we know that the buffer in fp is empty so 103 * we can read directly into buf. This is much faster than a 104 * series of one byte reads into fp->_nbuf. 105 */ 106 if ((fp->_flags & __SNBF) != 0 && buf != NULL) { 107 while (resid > 0) { 108 /* set up the buffer */ 109 fp->_bf._base = fp->_p = p; 110 fp->_bf._size = resid; 111 112 if (__srefill(fp)) { 113 /* no more input: return partial result */ 114 count = (total - resid) / size; 115 break; 116 } 117 p += fp->_r; 118 resid -= fp->_r; 119 } 120 121 /* restore the old buffer (see __smakebuf) */ 122 fp->_bf._base = fp->_p = fp->_nbuf; 123 fp->_bf._size = 1; 124 fp->_r = 0; 125 126 return (count); 127 } 128 129 while (resid > (r = fp->_r)) { 130 if (r != 0) { 131 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 132 fp->_p += r; 133 /* fp->_r = 0 ... done in __srefill */ 134 p += r; 135 resid -= r; 136 } 137 if (__srefill(fp)) { 138 /* no more input: return partial result */ 139 return ((total - resid) / size); 140 } 141 } 142 (void)memcpy((void *)p, (void *)fp->_p, resid); 143 fp->_r -= resid; 144 fp->_p += resid; 145 return (count); 146 } 147 148 __weak_reference(__fread, fread_unlocked); 149