fixed net.dostring_in("mission", "a_do_script(...)") causes SEGFAULT with non-scalar return values

[Actium]

Clean (no mods, no scripts), freshly repaired (full verification) DCS 2.9.13.6818 install. Running the following Lua code will cause a segmentation fault (ACCESS_VIOLATION):

local res = {net.dostring_in("mission", [[
	return {a_do_script("return {1, 2, 3, 4}", 1, 2, 3, 4)}
]])}

Steps to reproduce:

1. Save segfault_a_do_script.lua in %USERPROFILE%\Saved Games\DCS.openbeta\Scripts\Hooks\
2. Run an arbitrary mission from the mission editor.
3. Game should crash with a "DCS Crash" popup once loading completes.

Crash trace for comparison: dcs.20250224-084219.crash

How did I stumble upon this? I got curious what the updated a_do_script() can do and started messing around with it. Quote from the changelog:

Quote

Scripting API. Added possibility to pass args and return values from mission scripting a_do_script() and a_do_file() APIs.

Edited February 24 by Actium

[Actium]

The dedicated server is also affected (same lua.dll, presumably). The code does not cause a segfault with server version 2.9.12.5336.

Server crash trace: dcs.20250224-092739.crash

[Flappie]

Good news: the fix for the former issue you reported works for this issue as well.

[Actium]

@Flappie While said former issue has been fixed with 2.9.14.8222, above issue is still present.

[Flappie]

Thanks for your feedback. I'll try harder to reproduce the issue.

[Actium]

The steps to reproduce from my first posts still trigger the crash on both client and dedicated server.

dcs.20250320-214042.crash

 

[Flappie]

I'm able to reproduce the issue.

[Flappie]

@Actium Issue fixed with yesterday's update.

[MarcosR]

I was using this in my server and now i can't see any returned values ...  is there any other way i should be using this sentence?  

local safeScript = escape_lua_string(script)
local result = net.dostring_in("mission", " return a_do_script( \"" ..  safeScript .. "\" )" )

This was working before the update..

[MarcosR]

Just to clarify we don't get any result.. script gets ran on the mission side but the return value doesn't arrive back... any idea @Flappie?

[Actium]

@Flappie I can confirm that the fix presumably broke the underlying scripting feature entirely. Removed the solution mark.

@MarcosR I took the liberty to create a separate bug report for the issue you discovered, as it is kinda off topic here: