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From: philip@axis.UUCP
Newsgroups: net.unix,net.unix-wizards
Subject: Re: Not a typewriter
Message-ID: <717@axis.UUCP>
Date: Mon, 16-Jun-86 16:17:11 EDT
Article-I.D.: axis.717
Posted: Mon Jun 16 16:17:11 1986
Date-Received: Fri, 20-Jun-86 01:18:09 EDT
References: <1683@homxb.UUCP> <542@codas.ATT.UUCP>
Reply-To: philip@axis.UUCP (Philip Peake)
Organization: Axis Digital, 135 rue d'Aguesseau, Boulogne, 92100, FRANCE
Lines: 30
Xref: watmath net.unix:8223 net.unix-wizards:18458

In article <542@codas.ATT.UUCP> mikel@codas.UUCP writes:
>> What does the sys_errlist message 'Not a typewriter' *really* mean??
>
>I think there may be one or two system calls that will alter
>errno to be 25, without returning a non-zero value, when in
>fact there was no error.

This is true. *However*, if you look at the documentation *carefully*, you
will find that it says that errno is only valid if the system call preceeding
it returned an error value.

I agree that this is a disgusting state of affairs, and I have recently
had problems with a code segment as follows:


	fp = fopen(.....);
	errno = 0;
	..
	..
	loop: fwrite(.....);
	if (errno != 0) /* a write problem occured */
	{
		...
		...
	}
	..

This bombed out complaining about "Not a teletype", there was in fact,
no problem at all. The code came from a BSD4.? system, the machine on
which the problems occured runs S5.2.