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 "namespace.h" 39 #include <sys/types.h> 40 #include <errno.h> 41 #include <limits.h> 42 #include <stdio.h> 43 #include "un-namespace.h" 44 #include "local.h" 45 #include "libc_private.h" 46 47 /* 48 * standard ftell function. 49 */ 50 long 51 ftell(FILE *fp) 52 { 53 off_t rv; 54 55 rv = ftello(fp); 56 if (rv > LONG_MAX) { 57 errno = EOVERFLOW; 58 return (-1); 59 } 60 return (rv); 61 } 62 63 /* 64 * ftello: return current offset. 65 */ 66 off_t 67 ftello(FILE *fp) 68 { 69 fpos_t rv; 70 int ret; 71 72 FLOCKFILE(fp); 73 ret = _ftello(fp, &rv); 74 FUNLOCKFILE(fp); 75 if (ret) 76 return (-1); 77 if (rv < 0) { /* Unspecified value because of ungetc() at 0 */ 78 errno = ESPIPE; 79 return (-1); 80 } 81 return (rv); 82 } 83 84 int 85 _ftello(FILE *fp, fpos_t *offset) 86 { 87 fpos_t pos; 88 size_t n; 89 90 if (fp->_seek == NULL) { 91 errno = ESPIPE; /* historic practice */ 92 return (1); 93 } 94 95 /* 96 * Find offset of underlying I/O object, then 97 * adjust for buffered bytes. 98 */ 99 if (!(fp->_flags & __SRD) && (fp->_flags & __SWR) && 100 fp->_p != NULL && fp->_p - fp->_bf._base > 0 && 101 ((fp->_flags & __SAPP) || (fp->_flags2 & __S2OAP))) { 102 pos = _sseek(fp, (fpos_t)0, SEEK_END); 103 if (pos == -1) 104 return (1); 105 } else if (fp->_flags & __SOFF) 106 pos = fp->_offset; 107 else { 108 pos = _sseek(fp, (fpos_t)0, SEEK_CUR); 109 if (pos == -1) 110 return (1); 111 } 112 if (fp->_flags & __SRD) { 113 /* 114 * Reading. Any unread characters (including 115 * those from ungetc) cause the position to be 116 * smaller than that in the underlying object. 117 */ 118 if ((pos -= (HASUB(fp) ? fp->_ur : fp->_r)) < 0) { 119 fp->_flags |= __SERR; 120 errno = EIO; 121 return (1); 122 } 123 if (HASUB(fp)) 124 pos -= fp->_r; /* Can be negative at this point. */ 125 } else if ((fp->_flags & __SWR) && fp->_p != NULL && 126 (n = fp->_p - fp->_bf._base) > 0) { 127 /* 128 * Writing. Any buffered characters cause the 129 * position to be greater than that in the 130 * underlying object. 131 */ 132 if (pos > OFF_MAX - n) { 133 errno = EOVERFLOW; 134 return (1); 135 } 136 pos += n; 137 } 138 *offset = pos; 139 return (0); 140 } 141