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From: rpw3@amdcad.AMD.COM (Rob Warnock)
Newsgroups: comp.bugs.4bsd
Subject: Re: read() from tty has fencepost error
Message-ID: <17345@amdcad.AMD.COM>
Date: Wed, 1-Jul-87 19:07:50 EDT
Article-I.D.: amdcad.17345
Posted: Wed Jul  1 19:07:50 1987
Date-Received: Fri, 3-Jul-87 01:50:35 EDT
References: <648@haddock.UUCP> <6040@brl-smoke.ARPA> <13048@topaz.rutgers.edu>
Reply-To: rpw3@amdcad.UUCP (Rob Warnock)
Organization: [Consultant] San Mateo, CA
Lines: 25

My understanding has always been that <EOT> was a "push" which did not
store data in the stream.  By "push" I simply mean "return from the read
with whatever you've got so far.  (Under this interpretation, <LF> usually
means "store an <LF> then 'push'".) The function of <EOF> arises because
if you "push" at the beginning of a line (before data is typed), the "read()"
will return zero.

But if you "push" after N characters have been typed, you get N characters.

Therefore, by the "Principle Of [my own] Least Astonishment":

	abcde<EOT>

should return 5 characters, and the next call to "read()" should block.

In this case, System-V does it *right*!


Rob Warnock
Systems Architecture Consultant

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