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From: chris@umcp-cs.UUCP
Newsgroups: net.unix-wizards
Subject: Re: rcs problem
Message-ID: <6482@umcp-cs.UUCP>
Date: Tue, 10-Apr-84 05:04:00 EST
Article-I.D.: umcp-cs.6482
Posted: Tue Apr 10 05:04:00 1984
Date-Received: Wed, 11-Apr-84 05:43:46 EST
References: <971@qubix.UUCP>
Organization: Univ. of Maryland, Computer Science Dept.
Lines: 20

"_sobuf" and "_sibuf" are (the) two pre-allocated buffer areas that
the Berkeley stdio routines attach to stdin and stdout.  In order
to guarantee full (rather than line) buffering, the code

	extern char _sobuf[];
	setbuf (stout, _sobuf);

does the trick.  Of course it's not portable; nobody said stdio has
to have preallocated buffers named "_sobuf" and "_sibuf".

I'm really not sure why they did that, rather than just malloc()ing
the buffers the way the _iob[3] to _iob[NOFILE-1] are done ...
performance maybe.

[While I'm thinking of it:  Why, oh why, didn't they make "setbuf"
able to set line buffering???]
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci
UUCP:	{seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris.umcp-cs@CSNet-Relay