/* from Dale Schumacher's dLibs */

#include <stdio.h>
#include <unistd.h>
#include "lib.h"

static int	_fflush	__PROTO((FILE *));

int fflush(fp)
	register FILE *fp;
/*
 *	implementation note:  This function has the side effect of
 *	re-aligning the virtual file pointer (in the buffer) with
 *	the actual file pointer (in the file) and is therefore used
 *	in other functions to accomplish this re-sync operation.
 */
{
	register int f, i;

 	if(fp)
		return(_fflush(fp));
	else
		{
		for(i=0; i<_NFILE; ++i)
			{
			f = _iob[i]._flag;
			if(f & (_IOREAD | _IOWRT | _IORW))
				_fflush(&_iob[i]);
			}
		return(0);
		}
}

static int _fflush(fp)
	register FILE *fp;
{
	register int f, rv = 0;
	register long offset;

 	if(fp == NULL)
		return(0);
	f = fp->_flag;
      if (!(f & (_IORW | _IOREAD | _IOWRT)))  /* file not open */
		return(0);
	if(fp->_cnt > 0)	 		/* data in the buffer */
		{
  		if(f & _IOWRT)				/* writing */
  			{
			register long	todo;

			/* _cnt is cleared before writing to avoid */
			/* loop if fflush is recursively called by */
			/* exit if ^C is pressed during this write */
			todo = fp->_cnt;
			fp->_cnt = 0;
			if(_write(fp->_file, fp->_base, todo) != todo) 
				{
				fp->_flag |= _IOERR;
				rv = EOF;
				}
			}
		else if(f & _IOREAD) 			/* reading */
			{
			offset = -(fp->_cnt);
			if(lseek(fp->_file, offset, 1) < 0)
				rv = EOF;
			}
		}
	if(f & _IORW)
		fp->_flag &= ~(_IOREAD | _IOWRT);
	fp->_ptr = fp->_base;
	fp->_cnt = 0;
	return(rv);
}