Concerns regarding some library functions

[Austin Clements]

Quoth Ali Polatel on Sep 28 at 10:53 am:
> On Tue, 27 Sep 2011 18:46:22 -0400, Austin Clements <amdragon at MIT.EDU> wrote:
> > Quoth David Bremner on Sep 27 at  1:59 pm:
> > > On Tue, 27 Sep 2011 16:25:58 +0300, Ali Polatel <polatel at gmail.com> wrote:
> > > 
> > > > The problem with their design is NULL return may both mean an error
> > > > condition and "message not found". However, we already have a similar
> > > > function which does not have such a flaw, namely notmuch_database_add_message().
> > > 
> > > So, I take there is no way to distinguish those two outcomes? That does
> > > sound bad. Looking at the code for notmuch-new, it looks like the return
> > > value of notmuch_database_find_message_by_filename is used without
> > > checking it for NULL.  Austin, can you comment on that at all?
> > 
> > I'd be happy to distinguish these outcomes.  I did
> > notmuch_database_find_message_by_filename the way I did only to be
> > consistent with notmuch_database_find_message.  Since ndfmbf isn't
> > entrenched yet, now is a good time to change it.
> 
> What about notmuch_database_find_message()? If we leave it as it is,
> this will lead to inconsistency and if we change it, we need to think
> about API breakage issues.

Yes.  We could just deal with that (there aren't *that* many API
consumers).  For binary compatibility, I suppose we could even use
symbol versioning.

> > The call in notmuch-new should check the return, though if it can't
> > find the message at that point, something has gone terribly wrong.
> > Segfaulting is never the answer, though.
> 
> Indeed, just not to step on each other's feet, are you going to write a
> patch or shall I start writing one?

Please feel free to write a patch.