e54bc118c1
When file offset tends to be negative due to internal and ungetc buffers additions counted, try to discard some ungetc data first, then return EBADF. Later one can happens if lseek(fileno(fd),...) called f.e. POSIX says that ungetc beyond beginning of the file results are undefined, so we can just discard some of ungetc data in that case. Don't rely on gcc cast when checking for overflow, use OFF_MAX. Cosmetique.
143 lines
3.7 KiB
C
143 lines
3.7 KiB
C
/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Chris Torek.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)ftell.c 8.2 (Berkeley) 5/4/95";
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#endif
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static const char rcsid[] =
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"$FreeBSD$";
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#endif /* LIBC_SCCS and not lint */
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#include "namespace.h"
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#include <sys/types.h>
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#include <errno.h>
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#include <limits.h>
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#include <stdio.h>
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#include "un-namespace.h"
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#include "local.h"
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#include "libc_private.h"
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/*
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* standard ftell function.
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*/
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long
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ftell(fp)
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register FILE *fp;
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{
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register off_t rv;
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rv = ftello(fp);
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if (rv > LONG_MAX) {
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errno = EOVERFLOW;
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return (-1);
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}
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return (rv);
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}
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/*
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* ftello: return current offset.
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*/
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off_t
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ftello(fp)
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register FILE *fp;
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{
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register fpos_t pos;
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size_t n;
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if (fp->_seek == NULL) {
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errno = ESPIPE; /* historic practice */
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return (-1);
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}
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FLOCKFILE(fp);
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/*
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* Find offset of underlying I/O object, then
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* adjust for buffered bytes.
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*/
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if (fp->_flags & __SOFF)
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pos = fp->_offset;
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else {
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pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR);
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if (pos == -1) {
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FUNLOCKFILE(fp);
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return (-1);
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}
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}
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if (fp->_flags & __SRD) {
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/*
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* Reading. Any unread characters (including
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* those from ungetc) cause the position to be
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* smaller than that in the underlying object.
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*/
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pos -= fp->_r;
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if (pos < 0) {
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if (HASUB(fp)) {
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fp->_p -= pos;
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fp->_r += pos;
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pos = 0;
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} else {
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errno = EBADF;
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FUNLOCKFILE(fp);
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return (-1);
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}
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}
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if (HASUB(fp)) {
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pos -= fp->_ur;
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if (pos < 0) {
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errno = EBADF;
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FUNLOCKFILE(fp);
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return (-1);
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}
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}
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} else if ((fp->_flags & __SWR) && fp->_p != NULL) {
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/*
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* Writing. Any buffered characters cause the
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* position to be greater than that in the
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* underlying object.
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*/
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n = fp->_p - fp->_bf._base;
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if (pos > OFF_MAX - n) {
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FUNLOCKFILE(fp);
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errno = EOVERFLOW;
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return (-1);
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}
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pos += n;
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}
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FUNLOCKFILE(fp);
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return (pos);
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}
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