Set Transmit crashes on certain maps

[Velocity-plus]

OS: Linux
Game: CS:GO

Example map that crashes: trikz_advanced_csgo
Download: https://gamebanana.com/maps/170864

IMPORTANT: Please copy the full output.
--------------------------------------------------------
Checksum      : 5a60a1bae2f27f62a5aa05e68b7c835b
Date          : 2018-11-20 22:24:42.974079
OS            : Linux-4.15.0-38-generic-x86_64-with-debian-buster-sid
Game          : csgo
SP version    : 667
Github commit : 4b4d6a886456e7f59793af7ca0a9d2f098683b78
Server plugins:
   00: Source.Python, (C) 2012-2018, Source.Python Team.
   01: Metamod:Source 1.10.7-dev
SP plugins:
   00: transmit
--------------------------------------------------------

Nothing else was loaded with this code, I made a new file called transmit.py with the only following code

from entities.hooks import EntityCondition
from entities.hooks import EntityPreHook
from messages import SayText2
from players.entity import Player
from entities import CheckTransmitInfo
from entities.entity import BaseEntity
from memory import make_object
from entities.helpers import index_from_edict

@EntityPreHook(EntityCondition.is_not_player, 'set_transmit')
def pre_set_transmit(args):
        entity = make_object(BaseEntity, args[0])
        edict = make_object(CheckTransmitInfo, args[1]).client

        player = Player(index_from_edict(edict))
        # We always transmit the player to himself. If we don't, bad things happen.
        if player.index == entity.index:
            return None

It doesn't matter what EntityCondition is or if I use PreHook instead of EntityPreHook AND it does not matter what is inside the transmit function as long as transmit is hooked. This code crashes my server in many maps, a few maps do work, but I think there must be something wrong with PreHook.

[Ayuto]

What's the output of sp info? Also please include the imports in future. There is no reason to not include them unless you want to bother me. ;-)

[Velocity-plus]

Sorry that has been fixed. Now that we are on it, there is a similar issue with PostHook (they might be connected ? O.o), certainly not as important as this one, since there is a workaround for the other one, which is using a PreHook instead. #262

[Ayuto]

Thanks! Please also test it without Metamod/Sourcemod. This ensures a minimalistic testing environment.

[Velocity-plus]

Tested with only SourcePython, with only 1 file with this code. It still crashes :(

[Velocity-plus]

I have figured out why the crash was happening. When these two entities are being transmitted the server crashes (If the map contains these)

------ CRASHED REPORT ----
Entity: env_smoke
Entity: _firesmoke
------ CRASHED --------------

[Velocity-plus]

After further testing I have narrowed down the list:

crash_entities = ('env_fire', '_firesmoke', 'env_laser', 'func_rotating', 'prop_dynamic')
A work-around would be to check (in set_transmit hook) if an entity's classname is in crash_entities and then just return False This prevents crashing, but it is an odd thing to do, especially if they needs to be transmitted. I hope this is of any help @Ayuto .

Also, removing set_transmit hook crashes the server, fx: Function.remove_pre_hook(Entity(0).set_transmit, callback)

• Edit:
  Depending on the map, different entities can cause the server to crash, so this list won't fix it.

[Velocity-plus]

Would be great if the issue could have some kind of priority since set_transmit is awesome.

[jordanbriere]

Closing as this was fixed into 74c2b01. I've tested that map with your code just now and it is not crashing. After checking the SDK, that method is indeed internally calling itself for its parent: baseentity.cpp#L3660-L3664. So it was pretty much the same as the issue here.

[Velocity-plus]

@jordanbriere Can you briefly explain, what you mean by it was internally calling itself for its parent. I'm just curious how this got fixed because that was a very important issue (for my plugins at least). So that is cool.

[jordanbriere]

@jordanbriere Can you briefly explain, what you mean by it was internally calling itself for its parent. I'm just curious how this got fixed because that was a very important issue (for my plugins at least). So that is cool.

Suppose that function was written in Python, it would be something like this:

def set_transmit(entity):
    if entity.parent:
        set_transmit(entity.parent)

This would normally not be an issue, but the nested call caused a crash on Linux because at the time the alignment of the stack wasn't properly preserved within the hook. Ayuto fixed that into DynamicHooks and now it is working as intended. 😃