it is possible to build for boards without storage (so no Posix, no Fatafs), but still have scripts in ROMFS.
In this case we will use the backend AP_Filesystem_backend base class when doing file operations. This will alway fail to open directories, so when we try to load scripts from SCRIPTS_DIRECTORY it will always fail.
This leads to a warning being emitted:
Lua: State memory usage: 2796 + 5227
AP: Lua: open directory (./scripts) failed
AP: hello, world
Time has wrapped
Which isn't great.
Detect we are working on this filesystem and don't warn.
Implements a reasonably comfortable REPL accessible over serial entirely
as a loadable script.
Also accessible over MAVLink using QGroundControl's MAVLink Console and
the new mavport module.
Abstracts the MAVLink SERIAL_CONTROL message to be usable as a Lua port,
in particular the DEV_SHELL device supported by QGroundControl's MAVLink
Console.
Serial bindings were dependant on HAL_GCS_ENABLED but this is not ideal, it should be dependant on AP_SERIALMANAGER_ENABLED so that serial can function without GCS
In Lua, strings are the only type that come with a default metatable.
The metatable must be shared by all string objects, and it is set to be
the `string` library table each time that library is opened. In
Ardupilot's scripting engine, the last script to load then has access to
the string metatable as the library is opened fresh for each script, as
its `string` library will have been set to the metatable.
Therefore, if two scripts are loaded, A first and B second, and script B
executes e.g. `string.byte = "haha"`, then `string.byte()` and
`s:byte()` for script B are broken. Because the metatable is shared,
this also breaks `s:byte()` for script A, which violates the integrity
of the sandbox.
Fix the issue by disabling the metatable setup functionality when the
string libary is opened, then manually opening an additional copy of the
library (which won't be given to any script) and setting it as the
string metatable during intialization.
This will break any script that modifies the string metatable for
constructive purposes, but such a script could have been broken if it
weren't the only script running anyway.
Referencing the original function to run is of questionable value and
the only user uses it to grab the script environent from the upvalues.
Instead, use a reference to the script environment table directly.
Some bits of the code in the require machinery use the `lua_ref` to
access the script environment. However, this can change after the script
is rescheduled and it returns an arbitrary function to run next.
Resolve this by introducing `run_ref` which is specifically a reference
to the function to run next. `lua_ref` is preserved for the script
lifetime.
Move the string checks into the load functions to avoid duplicating it
for each binding.
Also sync up the return types to avoid an unnecessary conversion.
Saves ~1.5K.
The Lua stack is guaranteed to have at least LUA_MINSTACK (default 20)
slots upon entry to C. Check to see if we might need more than that
minimum and only in that case call the function to check and resize the
stack. In virtually all cases the check can then be optimized away.
Additionally remove the redundant "Out of stack" message. Lua already
says "stack overflow" and a null message is valid.
Saves ~330B.
This example intercepts PREFLIGHT_REBOOT_SHUTDOWN COMMAND_LONG's and if
param1==2, it shuts down the BQ40Z smart battery BMS. Otherwise it
passes through the COMMAND_LONG as a COMMAND_INT (this required updating
the gcs:run_command_int to return a MAV_RESULT rather than a bool).
This adds bindings for an I2CDevice's transfer() function, an example,
and removes the nil return hint from the get_device() docs as it never
actually returns nil.
Only create the binding object (singleton metatable/userdata or C
function reference) once the user first references a particular
singleton or userdata creation function. Once created, the object is
stored into the script's environment so it doesn't get recreated on the
next reference and there isn't any further overhead. The userdatas are
no longer shared between scripts which imposes a slight memory penalty
for multiple scripts using the same singleton but this avoids an
additional lookup time cost.
Userdata and ap_objects aren't eligible for this optimization as the C++
code might want a particular metatable at any time.
Saves ~9.3K Lua heap.
The global table is then used as the __index metamethod of each state's
environment table. Avoids the overhead of loading binding objects into
each state. The binding objects are immutable from Lua so sandboxing is
not violated.
Does have the slight downside that a script can no longer know all the
binding names by enumerating _ENV.
Saves ~700B of memory per loaded script.
The __call metamethod was set to the metatable itself. With __call not
present, Lua will try to call the metatable (and fail), which is the
same behavior as with the __call metamethod set to the metatable.
Saves ~2K Lua heap.
this has been tested on a marine engine, and correctly produces key
telemetry data
the NMEA_2000.lua module is broken out to make it easier to add other
NMEA 2000 based drivers
Peter Barker
Andrew Tridgell
yuri-rage
Tatsuya Yamaguchi
Randy Mackay
Willian Galvani
timtuxworth
Loki077
George Zogopoulos
Thomas Watson
Hayden Donald
Ian Burwell