Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!texbell!sequoia!rpp386!jfh
From: jfh@rpp386.cactus.org (John F. Haugh II)
Newsgroups: comp.unix.wizards
Subject: Re: how can I get filename from file descriptor?
Message-ID: <17109@rpp386.cactus.org>
Date: 7 Oct 89 14:28:33 GMT
References: <9353@chinet.chi.il.us> <1639@cbnewsl.ATT.COM> <10850@smoke.BRL.MIL> <14280@super.ORG> <11099@smoke.BRL.MIL> <862@cirrusl.UUCP> <11113@smoke.BRL.MIL> <867@cirrusl.UUCP> <1189@necisa.ho.necisa.oz> <947@cirrusl.UUCP>
Reply-To: jfh@rpp386.cactus.org (John F. Haugh II)
Organization: TrishTrash Readers, Inc.
Lines: 33

In article <947@cirrusl.UUCP> dhesi%cirrusl@oliveb.ATC.olivetti.com (Rahul Dhesi) writes:
>In article <1189@necisa.ho.necisa.oz> boyd@necisa.ho.necisa.oz (Boyd Roberts)
>writes:
>>There is no EOF in UNIX; ...
>>...A suitable stream line discipline would solve 
>>whatever your problem is.
>
>There *is* an EOF in UNIX.  Enough UNIX documentation says it that I
>believe it.  Case closed.

The only EOF UNIX has this lifetime is zero-length-read.  Until
you change your name to Ken Thompson, asserting UNIX needs a new
EOF mechanism is only going to draw stares.

The zero-length convention works -very- nicely compared to others
I've had the misfortune to use.  In particular, I'm much more fond
of 'while (read (...) > 0)' over Pascals 'while not eof (hi_mom) ...'

>The zero-length read/write strategy, besides not working for pipes,
>also doesn't work with buffered streams.  It's a pretty poor solution
>at this time.

Actually I think it's the best solution any has ever dreamt up.
The only objects which I am aware of supporting multiple EOFs are
tape devices [ and terminals, but more on that some other day ... ]

The zero-length-read paradigm has a very intuitve meaning.  It
means there is nothing left to read ...
-- 
John F. Haugh II                        +-Things you didn't want to know:------
VoiceNet: (512) 832-8832   Data: -8835  | The real meaning of MACH is ...
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