/***
*setvbuf.c - set buffer size for a stream
*
*	Copyright (c) 1985-1993, Microsoft Corporation. All rights reserved.
*
*Purpose:
*	defines setvbuf() - set the buffering mode and size for a stream.
*
*Revision History:
*	09-19-83  RN	initial version
*	06-26-85  TC	modified to allow user defined buffers of various sizes
*	06-24-86  DFW	kludged to fix incompatability with Xenix values of
*			_IOFBF, _IOLBF
*	02-09-87  JCR	added "buffer=&(_iob2[fileno(stream)]._charbuf);"
*			to handle _IONBF case
*	02-25-87  JCR	added support for default buffer and IBMC20-condition
*			code
*	04-13-87  JCR	changed type of szie from int to size_t (unsigned int)
*			and changed a related comparison
*	06-29-87  JCR	Took out the _OLD_IOFBF/_OLD_IOLBF kludge for MSC.
*			Should be taken out for IBM too...
*	09-28-87  JCR	Corrected _iob2 indexing (now uses _iob_index() macro).
*	11-02-87  JCR	Multi-thread support
*	12-11-87  JCR	Added "_LOAD_DS" to declaration
*	05-27-88  PHG	Merged DLL and normal versions
*	06-06-88  JCR	Optimized _iob2 references
*	06-14-88  JCR	Use near pointer to reference _iob[] entries
*	08-09-88  JCR	Buffer size can't be greater than INT_MAX
*	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	_iob[], _iob2[] merge. Also, cleanup, a little tuning
*			and 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 declarator.
*	04-27-93  CFW	Change _IONBF size to 2 bytes to hold wide char.
*
*******************************************************************************/

#include <cruntime.h>
#include <stdio.h>
#include <file2.h>
#include <assert.h>
#include <malloc.h>
#include <internal.h>
#include <os2dll.h>
#include <limits.h>

/***
*int setvbuf(stream, buffer, type, size) - set buffering for a file
*
*Purpose:
*	Controls buffering and buffer size for the specified stream.  The
*	array pointed to by buf is used as a buffer, unless NULL, in which
*	case we'll allocate a buffer automatically. type specifies the type
*	of buffering: _IONBF = no buffer, _IOFBF = buffered, _IOLBF = same
*	as _IOFBF.
*
*Entry:
*	FILE *stream - stream to control buffer on
*	char *buffer - pointer to buffer to use (NULL means auto allocate)
*	int type     - type of buffering (_IONBF, _IOFBF or _IOLBF)
*	size_t size  - size of buffer
*
*Exit:
*	return 0 if successful
*	returns non-zero if fails
*
*Exceptions:
*
*******************************************************************************/

int _CRTAPI1 setvbuf (
	FILE *str,
	char *buffer,
	int type,
	size_t size
	)
{
	REG1 FILE *stream;
#ifdef MTHREAD
	int index;
#endif
	int retval=0;	/* assume good return */

	assert(str != NULL);

	/*
	 * (1) Make sure type is one of the three legal values.
	 * (2) If we are buffering, make sure size is greater than 0.
	 */
	if ( (type != _IONBF) && ((size == 0) || (size > INT_MAX) ||
	((type != _IOFBF) && (type != _IOLBF))) )
		return(-1);

	/* force size to be even */
	size &= (size_t)~1;

	/*
	 * Init stream pointers
	 */
	stream = str;

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

	/*
	 * Flush the current buffer and free it, if it is ours.
	 */
	_flush(stream);
	_freebuf(stream);

	/*
	 * Clear a bunch of bits in stream->_flag (all bits related to
	 * buffering and those which used to be in stream2->_flag2). Most
	 * of these should never be set when setvbuf() is called, but it
	 * doesn't cost anything to be safe.
	 */
	stream->_flag &= ~(_IOMYBUF | _IOYOURBUF | _IONBF | _IOFEOF |
	_IOFLRTN | _IOCTRLZ);

	/*
	 * CASE 1: No Buffering.
	 */
	if (type & _IONBF) {
		stream->_flag |= _IONBF;
		buffer = (char *)&(stream->_charbuf);
		size = 2;
	}

	/*
	 * NOTE: Cases 2 and 3 (below) cover type == _IOFBF or type == _IOLBF
	 * Line buffering is treated as the same as full buffering, so the
	 * _IOLBF bit in stream->_flag is never set. Finally, since _IOFBF is
	 * defined to be 0, full buffering is simply assumed whenever _IONBF
	 * is not set.
	 */

	/*
	 * CASE 2: Default Buffering -- Allocate a buffer for the user.
	 */
	else if ( buffer == NULL ) {
		if ( (buffer = malloc(size)) == NULL ) {
			/*
			 * force library pre-termination procedure (placed here
			 * because the code path should almost never be hit)
			 */
			_cflush++;

			retval = -1;
			goto done;
		}
		stream->_flag |= _IOMYBUF;
	}

	/*
	 * CASE 3: User Buffering -- Use the buffer supplied by the user.
	 */
	else {
		stream->_flag |= _IOYOURBUF;
	}

	/*
	 * Common return for all cases.
	 */
	stream->_bufsiz = size;
	stream->_ptr = stream->_base = buffer;
	stream->_cnt = 0;
done:
	_unlock_str(index);
	return(retval);
}