Lua: fix crash in reloading Lua plugins that use FileHandler

Reloading Lua plugins did not actually remove registered FileHandler
instances which resulted in a use-after-free of lua_State. Fix this by
tracking instances and release them in wslua_deregister_filehandlers.

Other required fixes to allow reregistration after reloading:
- Fix END_FILEHANDLER_ROUTINE not to block all new registrations.
- wtap file subtypes are apparently persistent, even after
  "unregistering". Fix this by looking up the previous subtype that
  matches the FileHandler short name. Add a small sanity check to
  wtap_register_file_type_subtypes to prevent internal handlers from
  being overwritten.

This patch creates a potential memleak of registered_file_handlers as
wslua_deregister_filehandlers is not called on program exit (yet?).

Bug: 13264
Change-Id: I4f5935cde6ff8dc4de333359bad3efca96d4fb9b
Reviewed-on: https://code.wireshark.org/review/31068
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Peter Wu <peter@lekensteyn.nl>

0 files changed, 0 insertions, 0 deletions