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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 
     22 /*
     23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
     24  * Use is subject to license terms.
     25  */
     26 
     27 /*	Copyright (c) 1988 AT&T	*/
     28 /*	  All Rights Reserved  	*/
     29 
     30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     31 
     32 /*
     33  * Return file offset.
     34  * Coordinates with buffering.
     35  */
     36 #pragma weak _ftell = ftell
     37 
     38 #include "lint.h"
     39 #include "file64.h"
     40 #include "mtlib.h"
     41 #include <fcntl.h>
     42 #include <stdio.h>
     43 #include <thread.h>
     44 #include <synch.h>
     45 #include <errno.h>
     46 #include <unistd.h>
     47 #include <stddef.h>
     48 #include <limits.h>
     49 #include <sys/types.h>
     50 #include "stdiom.h"
     51 
     52 long
     53 ftell(FILE *iop)
     54 {
     55 	ptrdiff_t adjust;
     56 	off64_t	tres;
     57 	rmutex_t *lk;
     58 
     59 	FLOCKFILE(lk, iop);
     60 	if (iop->_cnt < 0)
     61 		iop->_cnt = 0;
     62 	if (iop->_flag & _IOREAD)
     63 		adjust = (ptrdiff_t)-iop->_cnt;
     64 	else if (iop->_flag & (_IOWRT | _IORW)) {
     65 		adjust = 0;
     66 		if (((iop->_flag & (_IOWRT | _IONBF)) == _IOWRT) &&
     67 		    (iop->_base != 0))
     68 			adjust = iop->_ptr - iop->_base;
     69 		else if ((iop->_flag & _IORW) && (iop->_base != 0))
     70 			adjust = (ptrdiff_t)-iop->_cnt;
     71 	} else {
     72 		errno = EBADF;	/* file descriptor refers to no open file */
     73 		FUNLOCKFILE(lk);
     74 		return (EOF);
     75 	}
     76 
     77 	tres = lseek64(FILENO(iop), 0, SEEK_CUR);
     78 	if (tres >= 0)
     79 		tres += adjust;
     80 
     81 	if (tres > LONG_MAX) {
     82 		errno = EOVERFLOW;
     83 		FUNLOCKFILE(lk);
     84 		return (EOF);
     85 	}
     86 
     87 	FUNLOCKFILE(lk);
     88 	return ((long)tres);
     89 }
     90