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: stable/12/lib/libc/stdio/ftell.c 326025 2017-11-20 19:49:47Z pfg $");
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
ftell(FILE * fp)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
ftello(FILE * fp)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
_ftello(FILE * fp,fpos_t * offset)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