Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!wugate!uunet!munnari.oz.au!csc!ccadfa!usage!basser!necisa!boyd
From: boyd@necisa.ho.necisa.oz (Boyd Roberts)
Newsgroups: comp.unix.wizards
Subject: Re: how can I get filename from file descriptor?
Message-ID: <1189@necisa.ho.necisa.oz>
Date: 29 Sep 89 00:38:17 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>
Organization: NEC Information Systems Australia Pty. Ltd.
Lines: 25

In article <867@cirrusl.UUCP> dhesi%cirrusl@oliveb.ATC.olivetti.com (Rahul Dhesi) writes:
>... Unfortunately this mechanism is not general enough,
>so a process writing to a pipe has no way of communicating the same
>thing that a user at a tty can communicate by typing the EOF
>character.
>

This is the old poor person's approach to IPC scenario.

There is no EOF in UNIX; read() returns 0 when there's nothing more to read.
Certain devices are able to return multiple read() 0 returns (ie. ttys), but
the situation is that when read() returns 0 THERE IS NO MORE DATA TO BE READ.

You are trying to avoid implementing a protocol that would provide the
_correct_ solution.  A suitable stream line discipline would solve 
whatever your problem is.

As someone once said:

    `Don't diddle the code, choose a better algorithm'


Boyd Roberts			boyd@necisa.ho.necisa.oz.au

``When the going gets wierd, the weird turn pro...''