snprintf() and sxprintf()

[PAD Powell]

The snprintf() function is a well behaved version of the ill-mannered
sprintf() function, in the sense that it provides a bound on the lenght
of the buffer that is used.  Unfortunately, without some additional
minor changes to _doprnt(), it is not TOTALLY problem free, but will at
least fail in a non-fatal manner.

In addition, sxprintf() is like snprintf(), but will not put a trailing
'\0' at the end.  This makes it useful in doing "form-filling".

Patrick Powell

/* @(#)sprintf.c	4.2 (Waterloo) 19/08/84 */
#include	<stdio.h>

/*	snprintf- sprintf with bounds check	*/
/*LINTLIBRARY*/
/*VARARGS3*/

char *snprintf(count, str, fmt, args)
int count;
char *str, *fmt;
{
	int s;
	struct _iobuf _strbuf;

	_strbuf._flag = _IOSTRG;
	_strbuf._ptr = str;
	_strbuf._cnt = count;
	s = _doprnt(fmt, &args, &_strbuf);
	if( s >= 0 ){
		if( _strbuf._cnt > 0 ){
			*_strbuf._ptr = 0;
		} else {
			s = -1;
		}
	}
	return(s < 0? NULL : str );
}

/*	sxprintf- exact count printf	*/

/*VARARGS3*/
char *sxprintf(count, str, fmt, args)
int count;
char *str, *fmt;
{
	int s;
	struct _iobuf _strbuf;

	_strbuf._flag = _IOSTRG;
	_strbuf._ptr = str;
	_strbuf._cnt = count;
	s = _doprnt(fmt, &args, &_strbuf);
	return(s < 0? NULL : str );
}