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From: peter@graffiti.UUCP (Peter da Silva)
Newsgroups: net.bugs.4bsd
Subject: Re: Bug in isatty (errno setting/clearing)
Message-ID: <156@graffiti.UUCP>
Date: Mon, 2-Sep-85 09:21:11 EDT
Article-I.D.: graffiti.156
Posted: Mon Sep  2 09:21:11 1985
Date-Received: Wed, 4-Sep-85 06:26:17 EDT
References: <965@sdcsvax.UUCP> <2200011@uiucuxc> <304@celerity.UUCP>
Organization: The Power Elite, Houston, TX
Lines: 15

> I got out MY V6 manuals and the following is a quote from the getc(III)
> 
> DIAGNOSTICS
> 	c-bit is set on EOF or error; from C, negative return indicates
> 	EOF.  Moreover, 'errno' is set by this routine just as it is for
> 	a system call (see introduction (II)).
> 
> Also putc, putw, fcreat, fflush, all happen to munge errno, as necessary.
> 
> So in V6, we have errno munged by the library routines in section 3.

And in V6 putc didn't wreck arguments with side-effects like V7 putc does,
because it's a macro. It'd be hard to ensure the behaviour of errno in a
macro, I would think. At the least it'd slow things down (losing a bit of why
you made it a macro in the first place). Also is this from libc or libS?