qa.c

/* QA.C -- Question & Answer routine for stdout and stdin */

/*  SPECIAL CASES ARE SITE SPECIFIC     */
/*      That is to say whether you get data on a read with eof/error. */

int _qaval_;    /* global cell for returned value (guaranteed to match) */
int _qacnt_;    /* global cell for number of characters read */

#include <stdio.h>

#ifdef THINK_C
	#include <unix.h>
#endif

#include "mixit.h"
#include "port.h"
#include "lclreadline.h"

int _qaflg_ = 1;    /* flag for these routines to bypass prompt */

#if !defined(fileno)
extern int fileno();    /* non-ANSI */
#endif

/*==========================================================================*/
/* returns 0 if a normal read occurs (at least '\n', and '\n' at end). 	 */
/* returns the number of characters read, plus one, for other valid reads.  */
/*  These could be caused by a line too long for your buffer, 				 */
/*  end of file, or other I/O errors. 										 */
/* returns EOF for end of file with no other characters. 					 */
/* returns (EOF - 1) for any other detected errors (in and/or out) 		 */
/*==========================================================================*/
int qa5(FILE *fin, FILE *fout, char *prompt, int bufsiz, char *buf)
{
	_qaval_ = (EOF)-1;              /* assume death 					 */
	_qacnt_ = 0;                        /* in case we die anytime soon 		 */

	if ( _qaflg_ && isatty(fileno(fout)) && isatty(fileno(fin)) )
	{
		/* this only happens if we should & all I/O is to a tty*/
		clearerr(fout);               /* start with no errors (ha ha) 	 */
		fflush(fout);                 /* shouldn't be necessary;  doesn't hurt*/
		if ( ferror(fout) )
			return _qaval_;             /* arggh! 							 */
#if !USE_READLINE
		fputs(prompt, fout);          /* present prompt 					 */
		if ( ferror(fout) )
			return _qaval_;             /* arggh! 							 */
		fflush(fout);                 /* shouldn't be necessary;  doesn't hurt*/
		if ( ferror(fout) )
			return _qaval_;             /* arggh! 							 */
#else
		return lclReadLine(fin,prompt,buf,bufsiz);
#endif
	}

	clearerr(fin);
	if ( fgets(buf, bufsiz, fin) )
	{                               /* get the answer 					 */
		_qacnt_ = strlen(buf);        /* find the size 					 */
		if ( ferror(fin) )
			return _qaval_;             /* arggh! 							 */
#if 0
		if ( feof( fin ) )
		return ( _qaval_ = EOF );   /* oops! 							 */
#endif
		if ( _qacnt_ > 0 )
			if ( buf[_qacnt_ - 1] == '\n' )
				return (_qaval_ = 0);
		return (_qaval_ = (_qacnt_ + 1));
	}

	if ( ferror(fin) )
		return _qaval_;                 /* arggh! 							 */

	return (_qaval_ = EOF);           /* end of file with no other chars 	 */
} /* end qa5 */


/*==========================================================================*/
/* error recovery for QA and QA5; flush the input buffer */
/*==========================================================================*/
void purge_qa2(FILE *fin, FILE *fout)
{
	char mybuf[256];                    /* a place to eat the garbage 		 */

	_qaflg_ = 0;                        /* turn off prompting entirely 		 */
	while ( (_qaval_ > 0) && (_qaval_ < EOF) )
		qa5(fin, fout, "", 256, mybuf); /* get some text 					 */

	_qaflg_ = 1;                        /* turn prompting back on 			 */
} /* end purge_qa2 */