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 */
47long
48ftell(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 */
63off_t
64ftello(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
81int
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