131 lines
3.5 KiB
C
131 lines
3.5 KiB
C
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/***
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*rewind.c - rewind a stream
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*
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* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines rewind() - rewinds a stream to the beginning.
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*
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*
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*Revision History:
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* 09-02-83 RN initial version
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* 11-02-87 JCR Multi-thread support
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* 12-11-87 JCR Added "_LOAD_DS" to declaration
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* 05-27-88 PHG Merged DLL/normal versions
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* 06-01-88 JCR Clear lowio flags as well as stdio flags
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* 06-14-88 JCR Near reference to _iob[] entries; improve REG variables
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* 08-25-88 GJF Don't use FP_OFF() macro for the 386
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* 08-18-89 GJF Clean up, now specific to OS/2 2.0 (i.e., 386 flat
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* model). Also fixed copyright and indents.
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* 02-15-90 GJF Fixed copyright
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* 03-19-90 GJF Made calling type _CALLTYPE1, added #include
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* <cruntime.h> and removed #include <register.h>.
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* 05-29-90 SBM Use _flush, not [_]fflush[_lk]
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* 07-23-90 SBM Replaced <assertm.h> by <assert.h>
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* 10-03-90 GJF New-style function declarators.
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* 01-22-91 GJF ANSI naming.
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* 03-27-92 DJM POSIX support.
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* 08-26-92 GJF Include unistd.h for POSIX build.
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* 04-06-93 SKS Replace _CRTAPI* with __cdecl
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* 11-09-93 GJF Merged in NT SDK version (a fix for POSIX bug).
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* Replaced MTHREAD with _MT.
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* 02-06-94 CFW assert -> _ASSERTE.
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* 03-07-95 GJF _[un]lock_str macros now take FILE * arg.
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* 06-12-95 GJF Replaced _osfile[] with _osfile() (macro referencing
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* field in ioinfo struct).
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* 07-25-95 GJF Replaced _osfile() with _osfile_safe().
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* 03-02-98 GJF Exception-safe locking.
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* 05-17-99 PML Remove all Macintosh support.
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*
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*******************************************************************************/
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#include <cruntime.h>
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#include <stdio.h>
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#include <file2.h>
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#include <dbgint.h>
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#include <io.h>
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#include <mtdll.h>
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#ifdef _POSIX_
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#include <unistd.h>
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#else
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#include <msdos.h>
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#endif
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#include <internal.h>
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/***
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*void rewind(stream) - rewind a string
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*
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*Purpose:
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* Back up a stream to the beginning (if not terminal). First flush it.
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* If read/write, allow next i/o operation to set mode.
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*
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*Entry:
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* FILE *stream - file to rewind
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*
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*Exit:
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* returns 0 if success
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* returns -1 if fails
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*
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*Exceptions:
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*
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*******************************************************************************/
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void __cdecl rewind (
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FILE *str
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)
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{
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REG1 FILE *stream;
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REG2 int fd;
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_ASSERTE(str != NULL);
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/* Init stream pointer */
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stream = str;
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#ifdef _POSIX_
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fd = fileno(stream);
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#else
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fd = _fileno(stream);
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#endif
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#ifdef _MT
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/* Lock the file */
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_lock_str(stream);
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__try {
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#endif
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/* Flush the stream */
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_flush(stream);
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/* Clear errors */
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stream->_flag &= ~(_IOERR|_IOEOF);
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#ifndef _POSIX_
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_osfile_safe(fd) &= ~(FEOFLAG);
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#endif
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/* Set flags */
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/* [note: _flush set _cnt=0 and _ptr=_base] */
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if (stream->_flag & _IORW)
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stream->_flag &= ~(_IOREAD|_IOWRT);
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/* Position to beginning of file */
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#ifdef _POSIX_
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/* [note: posix _flush doesn't discard buffer */
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stream->_ptr = stream->_base;
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stream->_cnt = 0;
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lseek(fd,0L,0);
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#else
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_lseek(fd,0L,0);
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#endif
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#ifdef _MT
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}
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__finally {
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/* unlock stream */
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_unlock_str(stream);
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}
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#endif
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}
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