148 lines
3.8 KiB
C
148 lines
3.8 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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fpos_t rv;
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int ret;
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/* make sure stdio is set up */
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if (!__sdidinit)
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__sinit();
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FLOCKFILE(fp);
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ret = _ftello(fp, &rv);
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FUNLOCKFILE(fp);
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if (ret)
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return (-1);
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if (rv < 0) /* Unspecified value because of ungetc() at 0 */
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rv = 0;
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return (rv);
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}
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int
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_ftello(fp, offset)
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register FILE *fp;
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fpos_t *offset;
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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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/*
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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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return (1);
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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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if ((pos -= (HASUB(fp) ? fp->_ur : fp->_r)) < 0) {
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fp->_flags |= __SERR;
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errno = EIO;
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return (1);
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}
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if (HASUB(fp))
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pos -= fp->_r; /* Can be negative at this point. */
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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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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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*offset = pos;
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return (0);
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}
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