Re: --with-cairo Emacs server crash and fix

[Liam Quinlan <liamkquinlan@gmail.com>]

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Alright cool.  I'll have a look at your changes for comparison.  Thanks for
the explanation.

On Tue, Aug 13, 2019, 11:00 Eli Zaretskii, <eliz@gnu.org> wrote:

> > From: Liam Quinlan <liamkquinlan@gmail.com>
> > Date: Mon, 12 Aug 2019 22:52:31 -0400
> > Cc: emacs-devel@gnu.org
> >
> > Update: i think I've found the actual proper solution.  Alternative
> patch on offer below; this time by checking for
> > dynamic bitmaps already in place after finishing the static ones in
> x_cr_init_fringe.  Note that that function also
> > defines w32_init_fringe if HAVE_NTGUI, so windows is covered.
>
> Yes, the idea is correct, but the implementation needed some tweaking,
> in particular due to w32 doing things a bit differently during
> startup.  See commit c90975f on the master branch.
>
> > Trying to be minimal so this example doesn't iterate to over
> fringe_bitmaps looking for sparse elements, just
> > begin checking fringe_bitmaps for existing elements at the index
> following the standard bitmaps leaves off and
> > continue until the first null.  I'm not sure if it's too bold to trust
> that holes haven't had a chance to arise though.
> > (perhaps if the server is initially used in console mode and packages
> get unloaded before a gui client
> > connects...?).
>
> No, we cannot assume there are no holes, you can clearly see in
> destroy_fringe_bitmap that it leaves holes if the destroyed bitmap is
> not the last one in the array.  So we need to initialize all the
> user-defined bitmaps whose pointer is not NULL.
>
> Btw, there's a simple way of reproducing the problem without any init
> files and extra packages:
>
>   emacs -Q -daemon
>   emacsclient SOME-VERSIONED-FILE-UNDER-GIT
>   M-x set variable RET diff-font-lock-prettify RET t RET
>   [modify the file and then save it]
>   C-x v =
>
> Before the change I pushed the above would fail to display the vc-diff
> bitmaps on the fringe (I presume the Cairo build will crash).  After
> the change, the bitmaps are displayed correctly.  This happens because
> diff-mode is loaded before the GUI frame is created, and thus the
> fringe bitmaps defined by diff-mode during loading are not completely
> initialized.
>
> Thanks.
>

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