Re: master ee6e4bc525: Update device-specific grab during drag-and-drop

Re: master ee6e4bc525: Update device-specific grab during drag-and-drop

[Lars Ingebrigtsen]

Po Lu via Mailing list for Emacs changes <emacs-diffs@gnu.org> writes:

>     Update device-specific grab during drag-and-drop
>
>     * src/xterm.c (x_detect_focus_change): Fix typo.
>     (handle_one_xevent): Set device if DND is in progress and update
>     device->grab.

This (or something other change in this area) leads to the following
warnings in an --with-x-toolkit=no build on the current Ubuntu:

xterm.c: In function 'handle_one_xevent':
xterm.c:21537:40: warning: potential null pointer dereference [-Wnull-dereference]
21537 |                           device->grab &= ~(1 << xev->detail);
      |                           ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
xterm.c:21537:40: warning: potential null pointer dereference [-Wnull-dereference]
21537 |                           device->grab &= ~(1 << xev->detail);
      |                                        ^~

I haven't checked whether it's a correct warning or not.

Re: master ee6e4bc525: Update device-specific grab during drag-and-drop

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Po Lu <luangruo@yahoo.com>
> Date: Sun, 21 Aug 2022 15:03:10 +0200
> 
> Po Lu via Mailing list for Emacs changes <emacs-diffs@gnu.org> writes:
> 
> >     Update device-specific grab during drag-and-drop
> >
> >     * src/xterm.c (x_detect_focus_change): Fix typo.
> >     (handle_one_xevent): Set device if DND is in progress and update
> >     device->grab.
> 
> This (or something other change in this area) leads to the following
> warnings in an --with-x-toolkit=no build on the current Ubuntu:
> 
> xterm.c: In function 'handle_one_xevent':
> xterm.c:21537:40: warning: potential null pointer dereference [-Wnull-dereference]
> 21537 |                           device->grab &= ~(1 << xev->detail);
>       |                           ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
> xterm.c:21537:40: warning: potential null pointer dereference [-Wnull-dereference]
> 21537 |                           device->grab &= ~(1 << xev->detail);
>       |                                        ^~

I tried to fix this now.

Re: master ee6e4bc525: Update device-specific grab during drag-and-drop

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> I tried to fix this now.

Yup; warning gone now.

Re: master ee6e4bc525: Update device-specific grab during drag-and-drop

[Po Lu]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> This (or something other change in this area) leads to the following
> warnings in an --with-x-toolkit=no build on the current Ubuntu:
>
> xterm.c: In function 'handle_one_xevent':
> xterm.c:21537:40: warning: potential null pointer dereference [-Wnull-dereference]
> 21537 |                           device->grab &= ~(1 << xev->detail);
>       |                           ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
> xterm.c:21537:40: warning: potential null pointer dereference [-Wnull-dereference]
> 21537 |                           device->grab &= ~(1 << xev->detail);
>       |                                        ^~
>
> I haven't checked whether it's a correct warning or not.

I guess it can happen if another bug makes Emacs "forget" devices, but I
fixed all of those at the end of May.

So for consistency I would enclose it with if (device), but I don't
think the NULL dereference can actually happen in reality.