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
ftell(FILE * fp)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
ftello(FILE * fp)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
_ftello(FILE * fp,fpos_t * offset)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