Re: [Tracker] PATCH: Fix segfault in tracker-ontologies (shows in tracker-miner-fs) when ontologies are missing

[Philip Van Hoof <philip codeminded be>]

Ho Jonatan,

I don't really agree with this approach. We should not 'just' check for 
NULL and let the software continue as if nothing happens. Invalid 
ontologies means that we can't go on. So abort() is probably the only 
sensible way out.

Trying to accept that stuff returns NULL and then happily continuing the 
rest of the software isn't really an option. Either the software can do 
its stuff and then it does it, or it can't and then it aborts (with an 
appropriate error message and/or error mechanism). Trying to continue 
and by that further destroying data and/or corrupt databases is not good.

In this case what could also be done, if you do want to improve 
error-handling, is that tracker-store returns an error for each and 
every of its D-Bus calls. I don't consider trying to handle NULL an 
improvement (rather, it's worse that way as you know about the problem 
later in the code rather than sooner this way).

Kind regards,

Philip

Jonatan Pålsson schreef op 8/08/2013 15:42:
> Hi list,
>
> When moving the ontology directory around (I recently submitted a
> patch for this functionality), I noticed that tracker-miner-fs
> segfaults when the ontologies are not found. I think there should be a
> check for ontology presence, and also ontology validity, but have not
> yet implemented this.
>
> I have however added some checks for the return value of the
> gvdb_table_list () function, which seems to return NULL when the gvdb
> files are bad. These files go bad when no ontologies are loaded.
>
> To reproduce the segfaults, move the $PREFIX/share/tracker/ontologies
> directory temporarily, so that it cannot be found. Or apply the
> previous patch which allows configuring the ontology directory path,
> and mess the path up from DConf ;)
>
> The following patch guards for NULLs when reading gvdb files during
> the loading of namespaces, classes and properties. Warning messages
> are printed when either of the aforementioned values are missing.
>
> Here's the patch:
> https://github.com/Pelagicore/tracker-ivi/commit/d643bbfe0442d43c83124aebc0c55470f5675117