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/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char rcsid[] = "$OpenBSD: ftell.c,v 1.2 1996/08/19 08:32:47 tholo Exp $";
#endif /* LIBC_SCCS and not lint */
#include <stdio.h>
#include <errno.h>
#include "local.h"
/*
* ftell: return current offset.
*/
long
ftell(fp)
register FILE *fp;
{
register fpos_t pos;
if (fp->_seek == NULL) {
errno = ESPIPE; /* historic practice */
return (-1L);
}
/*
* Find offset of underlying I/O object, then
* adjust for buffered bytes.
*/
__sflush(fp); /* may adjust seek offset on append stream */
if (fp->_flags & __SOFF)
pos = fp->_offset;
else {
pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR);
if (pos == -1L)
return (pos);
}
if (fp->_flags & __SRD) {
/*
* Reading. Any unread characters (including
* those from ungetc) cause the position to be
* smaller than that in the underlying object.
*/
pos -= fp->_r;
if (HASUB(fp))
pos -= fp->_ur;
} else if (fp->_flags & __SWR && fp->_p != NULL) {
/*
* Writing. Any buffered characters cause the
* position to be greater than that in the
* underlying object.
*/
pos += fp->_p - fp->_bf._base;
}
return (pos);
}
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