The original intent of catching throwable is to "sandbox" arbitrary
plugin logic and prevent it from ever accidentally killing threads on
the server. A LinkageError due to a missing or old dependency shouldn't
bring down the server, so we secure it by catching all exceptions around
plugin event handlers.
Trouble is, this also catches exceptions such as OutOfMemoryError or
ThreadDead, which assuredly should NOT be caught. The latter case has
even occured in the wild as seen by ticket 45 of TagAPI on BukkitDev.
Minecraft may terminate the reader and writer thread by calling stop(),
and this could occur within the event handler in a plugin. So we should
let ThreadDead go and propagate it to the appropriate handler in
Minecraft.
The original code attempted to parse the JavaScript as it went along,
counting open and close brackets. Unfortunately, this doesn't
take comments and string literals into consideration, so it would very
likely have failed with more complicated filters.
Instead, we'll let the JavaScript compiler handle all the complexity
and simply see if the code compiles. If it doesn't, but the error
occured in the last line, we assume it can be recovered by adding a
new line.
The filter command allows users with sufficient permission (or OPs) to
execute arbitrary JavaScript (no sandboxing). This is fine for a
debug and testing, but could potentially be exploited in a
production environment.
Instead, we disable this command by default and force users to enable it
specifically in the configuration file (not through commands). If
someone has access to the config.yml file, they probably also have
access to the plugins/ folder and thus the ability to install plugins
with arbitrary code execution as well.
Should ensure that packet listeners recieve the most up-to-date player
instance, regardless of whether or not the main thread is blocked in the
player listener. No more temporary players.
