ftell.c revision 23663
11573Srgrimes/*- 21573Srgrimes * Copyright (c) 1990, 1993 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This code is derived from software contributed to Berkeley by 61573Srgrimes * Chris Torek. 71573Srgrimes * 81573Srgrimes * Redistribution and use in source and binary forms, with or without 91573Srgrimes * modification, are permitted provided that the following conditions 101573Srgrimes * are met: 111573Srgrimes * 1. Redistributions of source code must retain the above copyright 121573Srgrimes * notice, this list of conditions and the following disclaimer. 131573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141573Srgrimes * notice, this list of conditions and the following disclaimer in the 151573Srgrimes * documentation and/or other materials provided with the distribution. 161573Srgrimes * 3. All advertising materials mentioning features or use of this software 171573Srgrimes * must display the following acknowledgement: 181573Srgrimes * This product includes software developed by the University of 191573Srgrimes * California, Berkeley and its contributors. 201573Srgrimes * 4. Neither the name of the University nor the names of its contributors 211573Srgrimes * may be used to endorse or promote products derived from this software 221573Srgrimes * without specific prior written permission. 231573Srgrimes * 241573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 251573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 261573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 271573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 281573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 291573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 301573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 311573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 321573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 331573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 341573Srgrimes * SUCH DAMAGE. 351573Srgrimes */ 361573Srgrimes 371573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 3816586Sjraynard#if 0 3923663Speterstatic char sccsid[] = "@(#)ftell.c 8.2 (Berkeley) 5/4/95"; 4016586Sjraynard#endif 4116586Sjraynardstatic const char rcsid[] = 4223663Speter "$Id: ftell.c,v 1.7 1997/02/22 15:02:07 peter Exp $"; 431573Srgrimes#endif /* LIBC_SCCS and not lint */ 441573Srgrimes 451573Srgrimes#include <stdio.h> 461573Srgrimes#include <errno.h> 471573Srgrimes#include "local.h" 4813545Sjulian#ifdef _THREAD_SAFE 4913545Sjulian#include <pthread.h> 5013545Sjulian#include "pthread_private.h" 5113545Sjulian#endif 521573Srgrimes 531573Srgrimes/* 541573Srgrimes * ftell: return current offset. 551573Srgrimes */ 561573Srgrimeslong 571573Srgrimesftell(fp) 5814790Spaul register FILE *fp; 591573Srgrimes{ 601573Srgrimes register fpos_t pos; 611573Srgrimes 621573Srgrimes if (fp->_seek == NULL) { 631573Srgrimes errno = ESPIPE; /* historic practice */ 641573Srgrimes return (-1L); 651573Srgrimes } 661573Srgrimes 6713545Sjulian#ifdef _THREAD_SAFE 6814840Sbde _thread_flockfile(fp, __FILE__, __LINE__); 6913545Sjulian#endif 701573Srgrimes /* 711573Srgrimes * Find offset of underlying I/O object, then 721573Srgrimes * adjust for buffered bytes. 731573Srgrimes */ 741573Srgrimes if (fp->_flags & __SOFF) 751573Srgrimes pos = fp->_offset; 761573Srgrimes else { 771573Srgrimes pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); 7814840Sbde if (pos == -1) { 7913545Sjulian#ifdef _THREAD_SAFE 8014840Sbde _thread_funlockfile(fp); 8113545Sjulian#endif 821573Srgrimes return (pos); 8313545Sjulian } 841573Srgrimes } 851573Srgrimes if (fp->_flags & __SRD) { 861573Srgrimes /* 871573Srgrimes * Reading. Any unread characters (including 881573Srgrimes * those from ungetc) cause the position to be 891573Srgrimes * smaller than that in the underlying object. 901573Srgrimes */ 911573Srgrimes pos -= fp->_r; 921573Srgrimes if (HASUB(fp)) 931573Srgrimes pos -= fp->_ur; 941573Srgrimes } else if (fp->_flags & __SWR && fp->_p != NULL) { 951573Srgrimes /* 961573Srgrimes * Writing. Any buffered characters cause the 971573Srgrimes * position to be greater than that in the 981573Srgrimes * underlying object. 991573Srgrimes */ 1001573Srgrimes pos += fp->_p - fp->_bf._base; 1011573Srgrimes } 10213545Sjulian#ifdef _THREAD_SAFE 10314840Sbde _thread_funlockfile(fp); 10413545Sjulian#endif 1051573Srgrimes return (pos); 1061573Srgrimes} 107