gtk: fix crash on Broadway GDK backend

The Broadway GDK backend does never sets event->string. This results in
a crash when filter_string_te_key_pressed_cb tries to read its contents.

Since the documentation marks reading the string as deprecated, try to
handle the character conversion here. It is based on
_gdk_x11_event_translate_keyboard_string (from gtk+), but without trying
to interpret Escape as '\033', and without trying to convert control
characters (example: Ctrl + 1). A buffer of 6 bytes is used to hold a
UTF-8 code point (there is no zero terminator, so 7 bytes as found in
the original implementation is unnecessary).

As g_locale_from_utf8 returns dynamically allocated memory, change the
control flow to have a single exit point where pointers are freed as
needed.

Reproduce with gtk3:
$ broadwayd :5
$ GDK_BACKEND=broadway BROADWAY_DISPLAY=:5 wireshark-gtk
(now open http://localhost:8085/ and start typing in the display filter)

Keys tested: e € (AltGr + 5) ü (AltGr + ", u)
In the X11 backend, these still get displayed correctly. In the broadway
backend however, the accents are missing due to a bug in the broadway
implementation.

Change-Id: Ic1f0ee2b87cd573023ee8e966f06489b3b744dcf
Reviewed-on: https://code.wireshark.org/review/5832
Reviewed-by: Balint Reczey <balint@balintreczey.hu>

0 files changed, 0 insertions, 0 deletions