Re: No error is returned to user if system settings plugin fails connection update

[Andrey Borzenkov <arvidjaar gmail com>]

On Tue, Mar 2, 2010 at 8:34 PM, Andrey Borzenkov <arvidjaar gmail com> wrote:
> On Tuesday 02 of March 2010 10:14:09 Dan Williams wrote:
>> On Sat, 2010-02-27 at 23:39 +0300, Andrey Borzenkov wrote:
>> > Using NM 0.8 + nm-applet 0.8 I hit the following situation - if
>> > ->update plugin method fails (for whatever reason - e.g. plugin is
>> > not able to create necessary file) - no error is returned to user.
>> > Error is correctly returned if creation of new system connection
>> > fails.
>> >
>> > I start nm-connection-editor and select system connection to
>> > modify. I correctly get authentication request and am able to
>> > modify connection (and save changes if no errors happened). But if
>> > there are errors inside of plugin during updating of connection
>> > settings, very funny situation results - logical state of NM is
>> > updated (i.e. if I start n-c-e again, I see my changes) but state
>> > in files on permanent storage is not updated, meaning restarting
>> > NM show again previous configuration.
>> >
>> > I verified that plugin really returns error, error is correctly set
>> > and plugin should be calling callback (in this case
>> > con_update_cb). This unfortunately pretty much ends my ability to
>> > debug it further - I am not good at D-Bus internals.
>>
>> So the flow *does* get to nm-sysconfig-connection.c's con_update_cb()
>> function,
>
> Yes
>
>> and the error is valid in that function?
>
> Yes
>
>> If you add a
>> g_message/fprintf of error->message there is that valid too?
>>
>
> update: DEBUG: /etc/sysconfig/network-scripts/ifcfg-eth0 ERROR ifcfg-
> mdv: DHCP_CLIENT_ID is not supported
> con_update_cb: DEBUG: connection error ifcfg-mdv: DHCP_CLIENT_ID is not
> supported
>
>

Sorry for reviving old thread, but it is still valid in 0.8.2. So far
there are two separate issues associated with it.

1) if plugin fails to write connection to stable store (for whatever
reasons) NM is left with old, cached, connection that was received fro
client. It makes impression that connection update worked (and it even
will work for as long as either NM is restarted or connection is
re-read again from disk). The reason is,
src/system-settings/nm-sysconfig-connection.c:pk_update_cb() first
updates in memory and then calls to save new definition. It is even
documented in comments :)

        /* Update our settings internally so the update() call will save the new
         * ones.

But if ->update fails, settings are not rolled back.

It could be possible; we could add old_connection field to PolkitCall
and use it to rollback in con_update_cb. Any potential issues
associated with it?

2) NM core does send proper error via D-Bus to nm-connection-editor,
but it simply does not have code to display them. On update it finally
calls connection_updated_cb() and it does not display anything (nor is
any error displayed on callback chain).

Hope this makes sense.