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