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From: dhesi@sun505.UUCP (Rahul Dhesi)
Newsgroups: comp.unix.wizards
Subject: Re: how can I get filename from file descriptor?
Message-ID: <862@cirrusl.UUCP>
Date: 18 Sep 89 18:29:15 GMT
References: <9353@chinet.chi.il.us> <1639@cbnewsl.ATT.COM> <10850@smoke.BRL.MIL> <14280@super.ORG> <11099@smoke.BRL.MIL>
Sender: news@cirrusl.UUCP
Reply-To: dhesi%cirrusl@oliveb.ATC.olivetti.com (Rahul Dhesi)
Organization: Cirrus Logic Inc.
Lines: 31

In article <11099@smoke.BRL.MIL> gwyn@brl.arpa (Doug Gwyn) writes:
>I did say that most pipe implementations don't support this.
>Back in the days of Sixth Edition UNIX, several sites implemented
>"pipe internal EOF".  It's clear that streams COULD implement this;
>I don't know whether or not the various flavors of streams do.
>Personally I think they should.

I think the wizards who are shaping the development of non-AT&T UNIX
should seriously consider including a general mechanism for sending an
out-of-band EOF.  Right now the concept of a zero-byte read from a tty
meaning EOF, and the zero-byte-write method describe above, are
hack-ish.

We already have out-of-band EOFs and other data here and there in
arbitrary places:  sockets have it, i'm told that TCP/IP supports some
sort of out-of-band data, and getc() supports it by returning int
instead of char.  It would be nice to have a general mechanism for
communicating a non-stick EOF (an EOF that is not a permanent EOF).
For example:

     write (fd, buf, -1);  /* write non-stick EOF */

     ...

     count = read (...);
     if (count == 0 && errno == ENSEOF) {
        ... got non-stick EOF sent by writer ... 
     }
--
Rahul Dhesi <dhesi%cirrusl@oliveb.ATC.olivetti.com>
UUCP:  oliveb!cirrusl!dhesi