1*f14fb602SLionel Sambuc /* $NetBSD: ftell.c,v 1.20 2012/03/27 15:05:42 christos Exp $ */
22fe8fb19SBen Gras
32fe8fb19SBen Gras /*-
42fe8fb19SBen Gras * Copyright (c) 1990, 1993
52fe8fb19SBen Gras * The Regents of the University of California. All rights reserved.
62fe8fb19SBen Gras *
72fe8fb19SBen Gras * This code is derived from software contributed to Berkeley by
82fe8fb19SBen Gras * Chris Torek.
92fe8fb19SBen Gras *
102fe8fb19SBen Gras * Redistribution and use in source and binary forms, with or without
112fe8fb19SBen Gras * modification, are permitted provided that the following conditions
122fe8fb19SBen Gras * are met:
132fe8fb19SBen Gras * 1. Redistributions of source code must retain the above copyright
142fe8fb19SBen Gras * notice, this list of conditions and the following disclaimer.
152fe8fb19SBen Gras * 2. Redistributions in binary form must reproduce the above copyright
162fe8fb19SBen Gras * notice, this list of conditions and the following disclaimer in the
172fe8fb19SBen Gras * documentation and/or other materials provided with the distribution.
182fe8fb19SBen Gras * 3. Neither the name of the University nor the names of its contributors
192fe8fb19SBen Gras * may be used to endorse or promote products derived from this software
202fe8fb19SBen Gras * without specific prior written permission.
212fe8fb19SBen Gras *
222fe8fb19SBen Gras * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
232fe8fb19SBen Gras * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
242fe8fb19SBen Gras * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
252fe8fb19SBen Gras * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
262fe8fb19SBen Gras * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
272fe8fb19SBen Gras * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
282fe8fb19SBen Gras * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
292fe8fb19SBen Gras * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
302fe8fb19SBen Gras * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
312fe8fb19SBen Gras * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
322fe8fb19SBen Gras * SUCH DAMAGE.
33b7061124SArun Thomas */
342fe8fb19SBen Gras
352fe8fb19SBen Gras #include <sys/cdefs.h>
362fe8fb19SBen Gras #if defined(LIBC_SCCS) && !defined(lint)
372fe8fb19SBen Gras #if 0
382fe8fb19SBen Gras static char sccsid[] = "@(#)ftell.c 8.2 (Berkeley) 5/4/95";
392fe8fb19SBen Gras #else
40*f14fb602SLionel Sambuc __RCSID("$NetBSD: ftell.c,v 1.20 2012/03/27 15:05:42 christos Exp $");
412fe8fb19SBen Gras #endif
422fe8fb19SBen Gras #endif /* LIBC_SCCS and not lint */
43b7061124SArun Thomas
44551374c2SErik van der Kouwe #include <assert.h>
452fe8fb19SBen Gras #include <errno.h>
46b7061124SArun Thomas #include <stdio.h>
472fe8fb19SBen Gras #include "reentrant.h"
482fe8fb19SBen Gras #include "local.h"
49b7061124SArun Thomas
502fe8fb19SBen Gras /*
512fe8fb19SBen Gras * ftell: return current offset.
522fe8fb19SBen Gras */
532fe8fb19SBen Gras long
ftell(FILE * fp)54*f14fb602SLionel Sambuc ftell(FILE *fp)
55b7061124SArun Thomas {
56*f14fb602SLionel Sambuc off_t pos;
572fe8fb19SBen Gras
582fe8fb19SBen Gras
592fe8fb19SBen Gras FLOCKFILE(fp);
602fe8fb19SBen Gras
612fe8fb19SBen Gras if (fp->_seek == NULL) {
622fe8fb19SBen Gras FUNLOCKFILE(fp);
632fe8fb19SBen Gras errno = ESPIPE; /* historic practice */
642fe8fb19SBen Gras return -1L;
65551374c2SErik van der Kouwe }
66551374c2SErik van der Kouwe
672fe8fb19SBen Gras /*
682fe8fb19SBen Gras * Find offset of underlying I/O object, then
692fe8fb19SBen Gras * adjust for buffered bytes.
702fe8fb19SBen Gras */
71*f14fb602SLionel Sambuc (void)__sflush(fp); /* may adjust seek offset on append stream */
722fe8fb19SBen Gras if (fp->_flags & __SOFF)
732fe8fb19SBen Gras pos = fp->_offset;
742fe8fb19SBen Gras else {
75*f14fb602SLionel Sambuc pos = (*fp->_seek)(fp->_cookie, (off_t)0, SEEK_CUR);
762fe8fb19SBen Gras if (pos == -1L) {
772fe8fb19SBen Gras FUNLOCKFILE(fp);
78*f14fb602SLionel Sambuc return (long)pos;
792fe8fb19SBen Gras }
802fe8fb19SBen Gras }
812fe8fb19SBen Gras if (fp->_flags & __SRD) {
822fe8fb19SBen Gras /*
832fe8fb19SBen Gras * Reading. Any unread characters (including
842fe8fb19SBen Gras * those from ungetc) cause the position to be
852fe8fb19SBen Gras * smaller than that in the underlying object.
862fe8fb19SBen Gras */
872fe8fb19SBen Gras pos -= fp->_r;
882fe8fb19SBen Gras if (HASUB(fp))
892fe8fb19SBen Gras pos -= fp->_ur;
902fe8fb19SBen Gras } else if (fp->_flags & __SWR && fp->_p != NULL) {
912fe8fb19SBen Gras /*
922fe8fb19SBen Gras * Writing. Any buffered characters cause the
932fe8fb19SBen Gras * position to be greater than that in the
942fe8fb19SBen Gras * underlying object.
952fe8fb19SBen Gras */
962fe8fb19SBen Gras pos += fp->_p - fp->_bf._base;
972fe8fb19SBen Gras }
982fe8fb19SBen Gras FUNLOCKFILE(fp);
99b7061124SArun Thomas
100*f14fb602SLionel Sambuc if (__long_overflow(pos)) {
1012fe8fb19SBen Gras errno = EOVERFLOW;
1022fe8fb19SBen Gras return -1L;
1032fe8fb19SBen Gras }
104b7061124SArun Thomas
105*f14fb602SLionel Sambuc return (long)pos;
106b7061124SArun Thomas }
107