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[] = "@(#)ftell.c 8.2 (Berkeley) 5/4/95"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "namespace.h" 42 #include <sys/types.h> 43 #include <errno.h> 44 #include <limits.h> 45 #include <stdio.h> 46 #include "un-namespace.h" 47 #include "local.h" 48 #include "libc_private.h" 49 50 /* 51 * standard ftell function. 52 */ 53 long 54 ftell(FILE *fp) 55 { 56 off_t rv; 57 58 rv = ftello(fp); 59 if (rv > LONG_MAX) { 60 errno = EOVERFLOW; 61 return (-1); 62 } 63 return (rv); 64 } 65 66 /* 67 * ftello: return current offset. 68 */ 69 off_t 70 ftello(FILE *fp) 71 { 72 fpos_t rv; 73 int ret; 74 75 FLOCKFILE(fp); 76 ret = _ftello(fp, &rv); 77 FUNLOCKFILE(fp); 78 if (ret) 79 return (-1); 80 if (rv < 0) { /* Unspecified value because of ungetc() at 0 */ 81 errno = ESPIPE; 82 return (-1); 83 } 84 return (rv); 85 } 86 87 int 88 _ftello(FILE *fp, fpos_t *offset) 89 { 90 fpos_t pos; 91 size_t n; 92 93 if (fp->_seek == NULL) { 94 errno = ESPIPE; /* historic practice */ 95 return (1); 96 } 97 98 /* 99 * Find offset of underlying I/O object, then 100 * adjust for buffered bytes. 101 */ 102 if (!(fp->_flags & __SRD) && (fp->_flags & __SWR) && 103 fp->_p != NULL && fp->_p - fp->_bf._base > 0 && 104 ((fp->_flags & __SAPP) || (fp->_flags2 & __S2OAP))) { 105 pos = _sseek(fp, (fpos_t)0, SEEK_END); 106 if (pos == -1) 107 return (1); 108 } else if (fp->_flags & __SOFF) 109 pos = fp->_offset; 110 else { 111 pos = _sseek(fp, (fpos_t)0, SEEK_CUR); 112 if (pos == -1) 113 return (1); 114 } 115 if (fp->_flags & __SRD) { 116 /* 117 * Reading. Any unread characters (including 118 * those from ungetc) cause the position to be 119 * smaller than that in the underlying object. 120 */ 121 if ((pos -= (HASUB(fp) ? fp->_ur : fp->_r)) < 0) { 122 fp->_flags |= __SERR; 123 errno = EIO; 124 return (1); 125 } 126 if (HASUB(fp)) 127 pos -= fp->_r; /* Can be negative at this point. */ 128 } else if ((fp->_flags & __SWR) && fp->_p != NULL && 129 (n = fp->_p - fp->_bf._base) > 0) { 130 /* 131 * Writing. Any buffered characters cause the 132 * position to be greater than that in the 133 * underlying object. 134 */ 135 if (pos > OFF_MAX - n) { 136 errno = EOVERFLOW; 137 return (1); 138 } 139 pos += n; 140 } 141 *offset = pos; 142 return (0); 143 } 144