text: /*-
   * 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. 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 sccsid[] = "@(#)ftell.c	8.2 (Berkeley) 5/4/95";
  #endif /* LIBC_SCCS and not lint */
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD: releng/11.0/lib/libc/stdio/ftell.c 290729 2015-11-12 22:24:39Z ache $");
  
  #include "namespace.h"
  #include <sys/types.h>
  #include <errno.h>
  #include <limits.h>
  #include <stdio.h>
  #include "un-namespace.h"
  #include "local.h"
  #include "libc_private.h"
  
  /*
   * standard ftell function.
   */
  long
  ftell(FILE *fp)
  {
  	off_t rv;
  
  	rv = ftello(fp);
  	if (rv > LONG_MAX) {
  		errno = EOVERFLOW;
  		return (-1);
  	}
  	return (rv);
  }
  
  /*
   * ftello: return current offset.
   */
  off_t
  ftello(FILE *fp)
  {
  	fpos_t rv;
  	int ret;
  
  	FLOCKFILE(fp);
  	ret = _ftello(fp, &rv);
  	FUNLOCKFILE(fp);
  	if (ret)
  		return (-1);
  	if (rv < 0) {   /* Unspecified value because of ungetc() at 0 */
  		errno = ESPIPE;
  		return (-1);
  	}
  	return (rv);
  }
  
  int
  _ftello(FILE *fp, fpos_t *offset)
  {
  	fpos_t pos;
  	size_t n;
  
  	if (fp->_seek == NULL) {
  		errno = ESPIPE;			/* historic practice */
  		return (1);
  	}
  
  	/*
  	 * Find offset of underlying I/O object, then
  	 * adjust for buffered bytes.
  	 */
  	if (!(fp->_flags & __SRD) && (fp->_flags & __SWR) &&
  	    fp->_p != NULL && fp->_p - fp->_bf._base > 0 &&
  	    ((fp->_flags & __SAPP) || (fp->_flags2 & __S2OAP))) {
  		pos = _sseek(fp, (fpos_t)0, SEEK_END);
  		if (pos == -1)
  			return (1);
  	} else if (fp->_flags & __SOFF)
  		pos = fp->_offset;
  	else {
  		pos = _sseek(fp, (fpos_t)0, SEEK_CUR);
  		if (pos == -1)
  			return (1);
  	}
  	if (fp->_flags & __SRD) {
  		/*
  		 * Reading.  Any unread characters (including
  		 * those from ungetc) cause the position to be
  		 * smaller than that in the underlying object.
  		 */
  		if ((pos -= (HASUB(fp) ? fp->_ur : fp->_r)) < 0) {
  			fp->_flags |= __SERR;
  			errno = EIO;
  			return (1);
  		}
  		if (HASUB(fp))
  			pos -= fp->_r;  /* Can be negative at this point. */
  	} else if ((fp->_flags & __SWR) && fp->_p != NULL &&
  	    (n = fp->_p - fp->_bf._base) > 0) {
  		/*
  		 * Writing.  Any buffered characters cause the
  		 * position to be greater than that in the
  		 * underlying object.
  		 */
  		if (pos > OFF_MAX - n) {
  			errno = EOVERFLOW;
  			return (1);
  		}
  		pos += n;
  	}
  	*offset = pos;
  	return (0);
  }
  