ftell.c revision 43782
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[] = 4243782Sdt "$Id: ftell.c,v 1.9 1998/04/11 07:40:44 jb Exp $"; 431573Srgrimes#endif /* LIBC_SCCS and not lint */ 441573Srgrimes 4543782Sdt#include <sys/types.h> 461573Srgrimes#include <stdio.h> 471573Srgrimes#include <errno.h> 481573Srgrimes#include "local.h" 4935129Sjb#include "libc_private.h" 501573Srgrimes 511573Srgrimes/* 5243782Sdt * standard ftell function. 531573Srgrimes */ 541573Srgrimeslong 551573Srgrimesftell(fp) 5614790Spaul register FILE *fp; 571573Srgrimes{ 5843782Sdt register off_t rv; 5943782Sdt rv = ftello(fp); 6043782Sdt if ((long)rv != rv) { 6143782Sdt errno = EOVERFLOW; 6243782Sdt return (-1); 6343782Sdt } 6443782Sdt return (rv); 6543782Sdt} 6643782Sdt 6743782Sdt/* 6843782Sdt * ftello: return current offset. 6943782Sdt */ 7043782Sdtoff_t 7143782Sdtftello(fp) 7243782Sdt register FILE *fp; 7343782Sdt{ 741573Srgrimes register fpos_t pos; 751573Srgrimes 761573Srgrimes if (fp->_seek == NULL) { 771573Srgrimes errno = ESPIPE; /* historic practice */ 781573Srgrimes return (-1L); 791573Srgrimes } 801573Srgrimes 8135129Sjb FLOCKFILE(fp); 821573Srgrimes /* 831573Srgrimes * Find offset of underlying I/O object, then 841573Srgrimes * adjust for buffered bytes. 851573Srgrimes */ 861573Srgrimes if (fp->_flags & __SOFF) 871573Srgrimes pos = fp->_offset; 881573Srgrimes else { 891573Srgrimes pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); 9014840Sbde if (pos == -1) { 9135129Sjb FUNLOCKFILE(fp); 921573Srgrimes return (pos); 9313545Sjulian } 941573Srgrimes } 951573Srgrimes if (fp->_flags & __SRD) { 961573Srgrimes /* 971573Srgrimes * Reading. Any unread characters (including 981573Srgrimes * those from ungetc) cause the position to be 991573Srgrimes * smaller than that in the underlying object. 1001573Srgrimes */ 1011573Srgrimes pos -= fp->_r; 1021573Srgrimes if (HASUB(fp)) 1031573Srgrimes pos -= fp->_ur; 1041573Srgrimes } else if (fp->_flags & __SWR && fp->_p != NULL) { 1051573Srgrimes /* 1061573Srgrimes * Writing. Any buffered characters cause the 1071573Srgrimes * position to be greater than that in the 1081573Srgrimes * underlying object. 1091573Srgrimes */ 1101573Srgrimes pos += fp->_p - fp->_bf._base; 1111573Srgrimes } 11235129Sjb FUNLOCKFILE(fp); 1131573Srgrimes return (pos); 1141573Srgrimes} 115