| From: Tom Christiansen <tchrist@jhereg.perl.com>
| Subject: Linux has a broken shutdown syscall!
| To: The Perl Porters Mailing List <perl5-porters@perl.org>
| Date: Fri, 24 Apr 1998 06:37:38 -0600
|
| Normally, one can exchange
|
| pipe(READER, WRITER)
|
| for
|
| socketpair(READER, WRITER, AF_UNIX, SOCK_STREAM, PF_UNIX);
| shutdown(READER, 1); # no more writing for reader
| shutdown(WRITER, 0); # no more reading for writer
|
| But guess what -- that doesn't work without fiddling!
|
| 1) The call to PF_UNIX must be PF_UNSPEC (or 0) on SunOS and BSD,
| even though it claims otherwise. There's some talk of PF_LOCAL,
| but that's not even documented outside BSD. Linux will accept
| either PF_UNIX or PF_UNSPEC there.
|
| 2) On Linux, shutdown is broken! You have to give it the opposite
| argument! You must perversely do this:
| shutdown(READER, 0);
| shutdown(WRITER, 1);
|
| Here's a suite that demonstrates this. Notice 1a and 1c, 2a and 2c.
| If you're on Linux, you'll have shutdown tell the reader not to
| read and the writer not to write. Very bizarre. On SunOS and BSD,
| you do the sane thing.
|
| Anybody have any clues about this?
|
| --tom
The full text of this article should be retrievable from:
http://www.rosat.mpe-garching.mpg.de/mailing-lists/perl-porters/1998-04/msg01409.html
Does anyone have more information to offer on this topic? It sounds
like Linux is not doing what the man page for shutdown(2) claims it's
doing:
| SHUTDOWN(2) Linux Programmer's Manual SHUTDOWN(2)
|
| NAME
| shutdown - shut down part of a full-duplex connection [...]
|
| DESCRIPTION
| The shutdown call causes all or part of a full-duplex con-
| nection on the socket associated with s to be shut down.
| If how is 0, further receives will be disallowed. If how
| is 1, further sends will be disallowed. If how is 2, fur-
| ther sends and receives will be disallowed. [...]
|
| CONFORMING TO
| 4.4BSD (the shutdown function call first appeared in
| 4.2BSD). [...]
|
| BSD Man Page 24 July 1993 1
If this belongs to the glibc people, please tell me, and I'll try to
forward it to them. (Better yet, forward it for me -- I don't know
their address.)
I tried searching the archives for references to this, but didn't find
anything obvious. If I'm missing something, please be reasonably
gentle with your enlightenment. :)
Thanks,
Tkil
--
Tkil * <URL: http://www.scrye.com/~tkil> * hopelessly hopeless romantic.
"So amplify this little one | She hears as much as she can see
She's a volume freak | And what she sees, she can't believe."
-- Catherine Wheel, _Happy Days_, "Judy Staring At The Sun"
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