WLua: Handle LUA error with %Z date format on Windows

[shancock884]

I came across an error using the Wireshark dissector on Windows, with messages containing unix time in μs.

Lua Error: ...Data\Roaming\Wireshark\plugins\mavlink_ardupilotmega.lua:22: bad argument #1 to 'date' (invalid conversion specifier '%Z')
    [Expert Info (Error/Undecoded): Lua Error: ...Data\Roaming\Wireshark\plugins\mavlink_ardupilotmega.lua:22: bad argument #1 to 'date' (invalid conversion specifier '%Z')]
        [Lua Error: ...Data\Roaming\Wireshark\plugins\mavlink_ardupilotmega.lua:22: bad argument #1 to 'date' (invalid conversion specifier '%Z')]
        [Severity level: Error]
        [Group: Undecoded]

The %Z date formatter should give the timezone as a short name, but it is not working on Lua 5.2.4 on Windows - as currently used in Wireshark. It worked on Linux, and is already fixed in Lua 5.3.3 or later, which I believe Wireshark will switch to at some point.

I have added code to the generator to catch the error, and if it occurs will instead use "%z" - which gives timezone as an offset instead.
So Windows users will see something like:

Payload: SYSTEM_TIME (2)
    time_unix_usec (uint64_t) [us]: 1718704143118600 (2024-06-18 10:49:03.118600 +0100)
    time_boot_ms (uint32_t) [ms]: 29935

When Wireshark is updated to use a newer Lua, it will give something like this (as Linux users see already):

Payload: SYSTEM_TIME (2)
    time_unix_usec (uint64_t) [us]: 1718704143118600 (2024-06-18 10:49:03.118600 BST)
    time_boot_ms (uint32_t) [ms]: 29935

Tested on my Windows setup, and the error is gone, and output as shown.

[peterbarker]

Why still draft?

[shancock884]

Why still draft?

Not sure! I think I planned to re-read my wording with a cup of tea, but got distratced!

[peterbarker]

Merged, thanks!