Re: dbus protocol change (truncate support)

[Alexander Larsson <alexl redhat com>]

On fre, 2013-10-25 at 17:30 +0200, Ross Lagerwall wrote:
> Hi,
>
> After a little more testing, I want to merge in the truncate support for
> the various backends that I implemented at:
> https://bugzilla.gnome.org/show_bug.cgi?id=573837
>
> The only issue seems to be that it requires a minor change to the dbus
> protocol which is "always painful" according to Tomas from the bug
> report.

Historically we've been pretty cavalier about this, considering the gvfs
protocol an internal detail that we break from one major release to
another if we have to. However, at some point we have to stop this and
give some level of stability guarantees. Especially as we're (slowly)
moving towards an app deployment system where you bundle the client
libraries with the app. Having such a system requires us to be able to
serve any older client library in a newer server.

I think the correct solution for this is to ensure that all our dbus
apis stay stable over time, and any time we need to modify them we do so
by adding new methods. 

In this particular case this means we need to support the old
gvfs_dbus_mount_call_open_for_write() dbus operation, and add a *new*
one that returns a set of flags rather than several boolean args. Then
old clients will still work with a simple forwarder to the new call on
the server side.

> It seems like the best time to make this change would be early in the
> release cycle, like now.  Is it OK to make it?

Yeah, sounds good to me.