Bug #66535 for X11-Protocol: infinite loop on read from closed connection

In recent debian X11::Protocol 0.56 and perl 5.10.1 if the server has closed the X connection then an attempt to read a reply or event from it goes into an apparently infinite loop using 100% cpu. The program foo.pl uses KillClient to ask the server to close the connection. It hangs at QueryPointer ... without going on to the "done". In FileHandle.pm and Socket.pm I think sysread() returns $n==0 for EOF from the server Doing the KillClient in the same client program might be a bit of a race condition, but at any rate reading after someone (anyone) has KillClient'ed the connection is the problem.

use strict; use X11::Protocol; print "DISPLAY $ENV{DISPLAY}\n"; my $X = X11::Protocol->new; my $pixmap = $X->new_rsrc; $X->CreatePixmap ($pixmap, $X->{'root'}, $X->{'root_depth'}, 1,1); # width,height $X->KillClient($pixmap); print "QueryPointer ...\n"; $X->QueryPointer($X->{'root'}); print "... done\n"; exit 0;

--- FileHandle.pm.orig 2011-02-28 17:57:40.000000000 +1100 +++ FileHandle.pm 2011-02-28 18:26:48.000000000 +1100 @@ -31,6 +31,7 @@ until ($o == $len) { $n = sysread $fh, $x, $len - $o, $o; croak $! unless defined $n; + croak "Connection closed" unless $n; # $n==0 EOF at server close $o += $n; } return $x;

--- Socket.pm.orig 2011-02-28 17:58:03.000000000 +1100 +++ Socket.pm 2011-02-28 18:26:49.000000000 +1100 @@ -31,6 +31,7 @@ until ($o == $len) { $n = $sock->sysread($x, $len - $o, $o); croak $! unless defined $n; + croak "Connection closed" unless $n; # $n==0 EOF at server close $o += $n; } return $x;