ignoring NEGOTIATE_UNIX_FD

[Martin Vidner]

On Sun, Nov 04, 2012 at 11:56:56PM +0100, Manuel Reimer wrote:
> So the next problem. My Idea was to create an "Inhibitor" from Perl.
> 
> use strict;
> use Net::DBus qw(:typing);
> 
> my $bus = Net::DBus->system;
> my $logind = $bus->get_service('org.freedesktop.login1');
> my $manager = $logind->get_object('/org/freedesktop/login1',
> 'org.freedesktop.login1.Manager');
> $manager->Inhibit('handle-power-key', 'testproc', 'testreason', 'block');
> 
> Result:
> 
> unknown type sig 'h' at
> /usr/lib/perl5/vendor_perl/Net/DBus/Binding/Introspector.pm line
> 810.
> I'm not interested in the return value, as the Inhibitor should run
> until my process ends (which closes all open file handles). So is
> there a simple way to just ignore the return value?

'h' is UNIX_FD, a newly added type, which is used in this API:
method QString org.freedesktop.login1.Manager.CreateSession(...[!],
   QDBusUnixFileDescriptor& fd, ...)

You could avoid it by avoiding the introspection call, I don't know
whether the Perl bindings can do that. I maintain the Ruby bindings,
and received a similar report
https://github.com/mvidner/ruby-dbus/pull/23 with a stop-gap fix of
recognizing 'h' but not handing the actual file descriptors.

But it got me thinking, wasn't NEGOTIATE_UNIX_FD supposed to avoid
this, by not letting older bindings see what they cannot handle unless
they ask for it?

Should the bus keep track of h-ignorant clients and filter the
introspection data so that they don't see "poisonous" APIs?

Should the spec be clarified to say that clients should recognize
'h' (and other future extensions) and ignore it?
-- 
Martin Vidner, ruby-dbus maintainer
https://github.com/mvidner/ruby-dbus

Kuracke oddeleni v restauraci je jako fekalni oddeleni v bazenu
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