ftell.c revision 82591
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[] = 4250476Speter "$FreeBSD: head/lib/libc/stdio/ftell.c 82591 2001-08-30 20:49:47Z ache $"; 431573Srgrimes#endif /* LIBC_SCCS and not lint */ 441573Srgrimes 4571579Sdeischen#include "namespace.h" 4643782Sdt#include <sys/types.h> 4782588Sache#include <errno.h> 4882588Sache#include <limits.h> 491573Srgrimes#include <stdio.h> 5071579Sdeischen#include "un-namespace.h" 511573Srgrimes#include "local.h" 5235129Sjb#include "libc_private.h" 531573Srgrimes 541573Srgrimes/* 5543782Sdt * standard ftell function. 561573Srgrimes */ 571573Srgrimeslong 581573Srgrimesftell(fp) 5914790Spaul register FILE *fp; 601573Srgrimes{ 6143782Sdt register off_t rv; 6282588Sache 6343782Sdt rv = ftello(fp); 6482588Sache if (rv > LONG_MAX) { 6543782Sdt errno = EOVERFLOW; 6643782Sdt return (-1); 6743782Sdt } 6843782Sdt return (rv); 6943782Sdt} 7043782Sdt 7143782Sdt/* 7243782Sdt * ftello: return current offset. 7343782Sdt */ 7443782Sdtoff_t 7543782Sdtftello(fp) 7643782Sdt register FILE *fp; 7743782Sdt{ 781573Srgrimes register fpos_t pos; 7982588Sache size_t n; 801573Srgrimes 811573Srgrimes if (fp->_seek == NULL) { 821573Srgrimes errno = ESPIPE; /* historic practice */ 8382588Sache return (-1); 841573Srgrimes } 851573Srgrimes 8635129Sjb FLOCKFILE(fp); 871573Srgrimes /* 881573Srgrimes * Find offset of underlying I/O object, then 891573Srgrimes * adjust for buffered bytes. 901573Srgrimes */ 911573Srgrimes if (fp->_flags & __SOFF) 921573Srgrimes pos = fp->_offset; 931573Srgrimes else { 941573Srgrimes pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); 9514840Sbde if (pos == -1) { 9635129Sjb FUNLOCKFILE(fp); 9782588Sache return (-1); 9813545Sjulian } 991573Srgrimes } 1001573Srgrimes if (fp->_flags & __SRD) { 1011573Srgrimes /* 1021573Srgrimes * Reading. Any unread characters (including 1031573Srgrimes * those from ungetc) cause the position to be 1041573Srgrimes * smaller than that in the underlying object. 1051573Srgrimes */ 1061573Srgrimes pos -= fp->_r; 10782588Sache if (pos < 0) { 10882588Sache if (HASUB(fp)) { 10982588Sache fp->_p -= pos; 11082588Sache fp->_r += pos; 11182588Sache pos = 0; 11282588Sache } else { 11382588Sache errno = EBADF; 11482588Sache FUNLOCKFILE(fp); 11582588Sache return (-1); 11682588Sache } 11782588Sache } 11882588Sache if (HASUB(fp)) { 1191573Srgrimes pos -= fp->_ur; 12082588Sache if (pos < 0) { 12182591Sache if (-pos <= fp->_r) { 12282591Sache fp->_p -= pos; 12382591Sache fp->_r += pos; 12482591Sache pos = 0; 12582591Sache } else { 12682591Sache errno = EBADF; 12782591Sache FUNLOCKFILE(fp); 12882591Sache return (-1); 12982591Sache } 13082588Sache } 13182588Sache } 13282588Sache } else if ((fp->_flags & __SWR) && fp->_p != NULL) { 1331573Srgrimes /* 1341573Srgrimes * Writing. Any buffered characters cause the 1351573Srgrimes * position to be greater than that in the 1361573Srgrimes * underlying object. 1371573Srgrimes */ 13882588Sache n = fp->_p - fp->_bf._base; 13982588Sache if (pos > OFF_MAX - n) { 14082588Sache FUNLOCKFILE(fp); 14182588Sache errno = EOVERFLOW; 14282588Sache return (-1); 14382588Sache } 14482588Sache pos += n; 1451573Srgrimes } 14635129Sjb FUNLOCKFILE(fp); 1471573Srgrimes return (pos); 1481573Srgrimes} 149