Re: IO::Select issue?

On Wed, 27 Oct 1999 10:17:09 EDT, Marc Pavese wrote:
>I posted the below message to comp.lang.perl.misc a day or two ago,
>and got no responses. Since the "fix" I found to my problem involved
>editing one line of IO::Socket, I'm forwarding this to you to ask if
>you have any advice. I'm not at all sure that my fix was right. If so,
>great. If not, I'm hoping you can set me straight.
>
>Thanks very much,
>
>Marc.
>
>--text follows this line--
>
>I am writing some perl client/server code that uses IO::Select
>(version 1.13), and I am having a problem with the IO::Select::exists
>method.
>
>At one point in my code, I call $select->exists on a client socket
>to determine whether or not it has been terminated. I usually get the
>following warning when I call it on a client which is in fact gone:
>
>Use of uninitialized value at
>/usr/lib/perl5/5.00503/ppc-linux/IO/Select.pm line 49.
>
>The following change to line 49 of IO::Select makes the error
>dissappear:
>
>--- /usr/lib/perl5/5.00503/ppc-linux/IO/Select.pm     Thu Jul 23 23:45:41 1998
>+++ Select.pm   Tue Oct 19 18:39:59 1999
>@@ -46,7 +46,7 @@
> sub exists
> {
>  my $vec = shift;
>- $vec->[$vec->_fileno(shift) + FIRST_FD];
>+ $vec->[ ($vec->_fileno(shift) || 0) + FIRST_FD];
> }                               
>
>What is happening is that $vec->_filenoo is returning undef on the
>passed in socket. When you try to add undef with FIRST_FD, you get the
>warning. 
>
>Could someone tell me if this change makes sense at all?  I checked,
>and in the only other place in IO::Socket where _fileno is used (in
>the _update subroutine), the case of undef is specifically tested for
>so I guess undef is not an unexpected return value from _fileno.

Try this.


Sarathy
gsar@ActiveState.com
-----------------------------------8<-----------------------------------
Change 4628 by gsar@auger on 1999/12/03 06:15:54

	avoid warning in IO::Select::exists() if socket doesn't exist

Affected files ...

... //depot/perl/ext/IO/lib/IO/Select.pm#8 edit

Differences ...

==== //depot/perl/ext/IO/lib/IO/Select.pm#8 (text) ====
Index: perl/ext/IO/lib/IO/Select.pm
--- perl/ext/IO/lib/IO/Select.pm.~1~	Thu Dec  2 22:17:34 1999
+++ perl/ext/IO/lib/IO/Select.pm	Thu Dec  2 22:17:34 1999
@@ -46,7 +46,9 @@
 sub exists
 {
  my $vec = shift;
- $vec->[$vec->_fileno(shift) + FIRST_FD];
+ my $fno = $vec->_fileno(shift);
+ return undef unless defined $fno;
+ $vec->[$fno + FIRST_FD];
 }
 
 
End of Patch.

• IO::Select issue? by Marc Pavese
• Re: IO::Select issue? by Gurusamy Sarathy
• Re: IO::Select issue? by Ilya Zakharevich