1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 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(fp); 58 ret = __fread(buf, size, count, fp); 59 FUNLOCKFILE(fp); 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 while (resid > (r = fp->_r)) { 101 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 102 fp->_p += r; 103 /* fp->_r = 0 ... done in __srefill */ 104 p += r; 105 resid -= r; 106 if (__srefill(fp)) { 107 /* no more input: return partial result */ 108 return ((total - resid) / size); 109 } 110 } 111 (void)memcpy((void *)p, (void *)fp->_p, resid); 112 fp->_r -= resid; 113 fp->_p += resid; 114 return (count); 115 } 116