2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 #if defined(LIBC_SCCS) && !defined(lint)
39 static char sccsid[] = "@(#)ftell.c 8.2 (Berkeley) 5/4/95";
41 static const char rcsid[] =
43 #endif /* LIBC_SCCS and not lint */
45 #include <sys/types.h>
49 #include "libc_private.h"
52 * standard ftell function.
68 * ftello: return current offset.
76 if (fp->_seek == NULL) {
77 errno = ESPIPE; /* historic practice */
83 * Find offset of underlying I/O object, then
84 * adjust for buffered bytes.
86 if (fp->_flags & __SOFF)
89 pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR);
95 if (fp->_flags & __SRD) {
97 * Reading. Any unread characters (including
98 * those from ungetc) cause the position to be
99 * smaller than that in the underlying object.
104 } else if (fp->_flags & __SWR && fp->_p != NULL) {
106 * Writing. Any buffered characters cause the
107 * position to be greater than that in the
110 pos += fp->_p - fp->_bf._base;