/***
*rewind.c - rewind a stream
*
*	Copyright (c) 1985-1992, Microsoft Corporation. All rights reserved.
*
*Purpose:
*	defines rewind() - rewinds a stream to the beginning.
*
*
*Revision History:
*	09-02-83  RN	initial version
*	11-02-87  JCR	Multi-thread support
*	12-11-87  JCR	Added "_LOAD_DS" to declaration
*	05-27-88  PHG	Merged DLL/normal versions
*	06-01-88  JCR	Clear lowio flags as well as stdio flags
*	06-14-88  JCR	Near reference to _iob[] entries; improve REG variables
*	08-25-88  GJF	Don't use FP_OFF() macro for the 386
*	08-18-89  GJF	Clean up, now specific to OS/2 2.0 (i.e., 386 flat
*			model). Also fixed copyright and indents.
*	02-15-90  GJF	Fixed copyright
*	03-19-90  GJF	Made calling type _CALLTYPE1, added #include
*			<cruntime.h> and removed #include <register.h>.
*	05-29-90  SBM   Use _flush, not [_]fflush[_lk]
*	07-23-90  SBM	Replaced <assertm.h> by <assert.h>
*	10-03-90  GJF	New-style function declarators.
*	01-22-91  GJF	ANSI naming.
*	03-27-92  DJM	POSIX support.
*	08-26-92  GJF	Include unistd.h for POSIX build.
*
*******************************************************************************/

#include <cruntime.h>
#include <stdio.h>
#include <file2.h>
#include <assert.h>
#include <io.h>
#include <os2dll.h>
#ifdef	_POSIX_
#include <unistd.h>
#else
#include <msdos.h>
#endif
#include <internal.h>

/***
*void rewind(stream) - rewind a string
*
*Purpose:
*	Back up a stream to the beginning (if not terminal).  First flush it.
*	If read/write, allow next i/o operation to set mode.
*
*Entry:
*	FILE *stream - file to rewind
*
*Exit:
*	returns 0 if success
*	returns -1 if fails
*
*Exceptions:
*
*******************************************************************************/

void _CALLTYPE1 rewind (
	FILE *str
	)
{
	REG1 FILE *stream;
	REG2 int fd;
#ifdef MTHREAD
	int index;
#endif

	assert(str != NULL);

	/* Init stream pointer */
	stream = str;

#ifdef _POSIX_
	fd = fileno(stream);
#else
	fd = _fileno(stream);
#endif

	/* Get the stream index and lock the file */
#ifdef MTHREAD
	index = _iob_index(stream);
#endif
	_lock_str(index);

	/* Flush the stream */
 	_flush(stream);

	/* Clear errors */
	stream->_flag &= ~(_IOERR|_IOEOF);
#ifndef _POSIX_
	_osfile[fd] &= ~(FEOFLAG);
#endif

	/* Set flags */
	/* [note: _flush set _cnt=0 and _ptr=_base] */
	if (stream->_flag & _IORW)
		stream->_flag &= ~(_IOREAD|_IOWRT);

	/* Position to beginning of file */
#ifdef _POSIX_
	/* [note: posix _flush doesn't discard buffer */

	stream->_ptr = stream->_base;
	stream->_cnt = 0;
	lseek(fd,0L,0);
#else
	_lseek(fd,0L,0);
#endif

	/* unlock stream */
	_unlock_str(index);
}