ftell.c revision 82670
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 82670 2001-08-31 18:54:44Z 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{ 7882668Sache register off_t rv; 7982668Sache 8082668Sache FLOCKFILE(fp); 8182668Sache rv = _ftello(fp); 8282668Sache FUNLOCKFILE(fp); 8382668Sache return (rv); 8482668Sache} 8582668Sache 8682668Sacheoff_t 8782668Sache_ftello(fp) 8882668Sache register FILE *fp; 8982668Sache{ 9082659Sache register fpos_t pos, spos; 9182588Sache size_t n; 921573Srgrimes 931573Srgrimes if (fp->_seek == NULL) { 941573Srgrimes errno = ESPIPE; /* historic practice */ 9582588Sache return (-1); 961573Srgrimes } 971573Srgrimes 981573Srgrimes /* 991573Srgrimes * Find offset of underlying I/O object, then 1001573Srgrimes * adjust for buffered bytes. 1011573Srgrimes */ 10282668Sache if (fp->_flags & __SOFF) { 1031573Srgrimes pos = fp->_offset; 10482668Sache spos = -1; 10582668Sache } else { 10682668Sacheget_real_pos: 10782668Sache spos = pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); 10882668Sache if (pos == -1) 10982588Sache return (-1); 1101573Srgrimes } 1111573Srgrimes if (fp->_flags & __SRD) { 1121573Srgrimes /* 1131573Srgrimes * Reading. Any unread characters (including 1141573Srgrimes * those from ungetc) cause the position to be 1151573Srgrimes * smaller than that in the underlying object. 1161573Srgrimes */ 1171573Srgrimes pos -= fp->_r; 11882588Sache if (pos < 0) { 11982588Sache if (HASUB(fp)) { 12082588Sache fp->_p -= pos; 12182588Sache fp->_r += pos; 12282588Sache pos = 0; 12382588Sache } else { 12482670Sache fp->_p = fp->_bf._base; 12582670Sache fp->_r = 0; 12682668Sache if (spos == -1) 12782668Sache goto get_real_pos; 12882659Sache pos = spos; 12982588Sache } 13082588Sache } 13182588Sache if (HASUB(fp)) { 1321573Srgrimes pos -= fp->_ur; 13382588Sache if (pos < 0) { 13482591Sache if (-pos <= fp->_r) { 13582591Sache fp->_p -= pos; 13682591Sache fp->_r += pos; 13782591Sache pos = 0; 13882591Sache } else { 13982659Sache fp->_p = fp->_bf._base; 14082659Sache fp->_r = 0; 14182659Sache FREEUB(fp); 14282670Sache if (spos == -1) 14382670Sache goto get_real_pos; 14482659Sache pos = spos; 14582591Sache } 14682588Sache } 14782588Sache } 14882588Sache } else if ((fp->_flags & __SWR) && fp->_p != NULL) { 1491573Srgrimes /* 1501573Srgrimes * Writing. Any buffered characters cause the 1511573Srgrimes * position to be greater than that in the 1521573Srgrimes * underlying object. 1531573Srgrimes */ 15482588Sache n = fp->_p - fp->_bf._base; 15582588Sache if (pos > OFF_MAX - n) { 15682588Sache errno = EOVERFLOW; 15782588Sache return (-1); 15882588Sache } 15982588Sache pos += n; 1601573Srgrimes } 1611573Srgrimes return (pos); 1621573Srgrimes} 163