Xref: utzoo comp.unix.wizards:16834 comp.unix.questions:14180
Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!unisoft!tccc0!eric
From: eric@tccc0.UUCP (Eric Smith)
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: Re: keyscan wanted
Message-ID: <12@tccc0.UUCP>
Date: 7 Jun 89 03:16:45 GMT
References: <1006@twwells.uucp> <607@wn2.sci.kun.nl>
Reply-To: eric@tccc0.UUCP (Eric Smith)
Organization: TFS -- Berkeley, California
Lines: 18

>int key_pressed()
>{
>	int mask=1;
>	struct timeval wait;
>
>	wait.tv_sec=0;
>	wait.tv_usec=0;
>	return (select(1,&mask,0,0,&wait));
>}

For that to work reliably, you must make sure the stdin buffer is empty
before calling key_pressed, because the select call doesn't check for
characters already in the stdin buffer.  In some applications using raw
mode this could be very hard to debug unless you had some hints (such as
this one) because an undetected character in the stdin buffer might only
happen very rarely and randomly.  To check for characters in the stdin
buffer, you can look at stdin->_cnt, which tells how many characters,
so it should be 0 to proceed with the key_pressed call.