136 lines
4.1 KiB
C
136 lines
4.1 KiB
C
/* ftell.c - remember a position in a file. stdio.h */
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/* Copyright 1992-1993 Wind River Systems, Inc. */
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/*
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modification history
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--------------------
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01c,05mar93,jdi documentation cleanup for 5.1.
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01b,20sep92,smb documentation additions
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01a,29jul92,jcf Added OBJ_VERIFY
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+smb taken from UCB stdio
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*/
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/*
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DESCRIPTION
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* Copyright (c) 1990 The Regents of the University of California.
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* 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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INCLUDE FILE: stdio.h, error.h
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SEE ALSO: American National Standard X3.159-1989
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NOMANUAL
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*/
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#include "vxWorks.h"
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#include "stdio.h"
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#include "errno.h"
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#include "objLib.h"
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#include "private/stdioP.h"
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/******************************************************************************
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*
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* ftell - return the current value of the file position indicator for a stream (ANSI)
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*
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* This routine returns the current value of the file position indicator for
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* a specified stream. For a binary stream, the value is the number of
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* characters from the beginning of the file. For a text stream, the file
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* position indicator contains unspecified information, usable by fseek() for
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* returning the file position indicator to its position at the time of the
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* ftell() call; the difference between two such return values is not
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* necessary a meaningful measure of the number of characters written or read.
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*
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* INCLUDE FILES: stdio.h
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*
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* RETURNS:
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* The current value of the file position indicator,
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* or -1L if unsuccessful, with `errno' set to indicate the error.
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*
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* SEE ALSO: fseek()
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*/
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long ftell
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(
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FAST FILE * fp /* stream */
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)
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{
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FAST fpos_t pos;
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if (OBJ_VERIFY (fp, fpClassId) != OK)
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return (ERROR);
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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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{
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pos = __sseek (fp, (fpos_t)0, SEEK_CUR);
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if (pos == -1L)
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return (pos);
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}
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if (fp->_flags & __SRD)
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{
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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 (HASUB(fp))
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pos -= fp->_ur;
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}
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else if (fp->_flags & __SWR && fp->_p != NULL)
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{
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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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pos += fp->_p - fp->_bf._base;
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}
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return (pos);
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}
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