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