Minetest: Crash when calling remove_detached_inventory during mod load

[FaceDeer]

Minetest version

5.0.1

OS / Hardware

Operating system: Windows 10 Home
CPU: Intel i7-3770K @ 3.5GHz, 8.00 GB ram

Summary

It appears that attempting to call minetest.remove_detached_inventory on a detached inventory while mods are still loading will cause an immediate crash to desktop, with no debugging output recorded about any further details.

Steps to reproduce

A mod with the following init.lua reliably reproduces the problem:

local test = minetest.create_detached_inventory("test", {})
test:set_size("main", 1)

minetest.remove_detached_inventory("test") -- this kills the Minetest

minetest.after(5, function()
    local success = minetest.remove_detached_inventory("test") -- this one works fine though
    minetest.chat_send_all("Success: " .. tostring(success))
end)

Commenting out the first detached causes the game to load without crashing, and five seconds later success at removing the detached inventory is reported.

I discovered this issue when attempting to override the behaviour of the "creative" mod's trash inventory in Digtron 2.0. I wanted to catch certain items being placed in the trash so I could read metadata off of their itemstacks and clean up some records tracking them, so I tried deleting and recreating the creative_trash detached inventory with additional code in its on_put callback. I can put this into an "after" function as a workaround (as illustrated in this test mod), can't think of any other way to do it unfortunately.

[SmallJoker]

1) Where do you guys get such ideas from? Like seriously?
2) gdb minetest

Thread 1 "minetest_occlus" received signal SIGSEGV, Segmentation fault.
0x0000555555be056a in ServerEnvironment::getPlayer(char const*) ()
(gdb) bt
#0  0x0000555555be056a in ServerEnvironment::getPlayer(char const*) ()
#1  0x0000555555bc5ef5 in Server::removeDetachedInventory(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) ()
#2  0x000055555599850b in ModApiInventory::l_remove_detached_inventory_raw(lua_State*) ()

EDIT: As a workaround, you can read the definition from minetest.detached_inventories[name] and call minetest.create_detached_inventory() again to override the fields. Or just override the table directly because Minetest does not keep any definition data in C++.

[SmallJoker]

b8131c3
Also includes a fix for calling the function with a player name.

[FaceDeer]

Ah, excellent, I'll be able to copy the original on_put function pointer from the existing definition and call it after I do my Digtron-specific stuff. That'll be more robust against potential future changes in the creative mod.

I like to think that I haven't really been _seriously_ modding until I discover a new issue I can file here. Just wait until I test what happens when I try overriding an ObjectRef's remove() method, I'm sure that's not going to work at all like I'm hoping. :)