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Segfault on AI trying to build a valid tunnel #2875

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DorpsGek opened this issue Apr 30, 2009 · 4 comments
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Segfault on AI trying to build a valid tunnel #2875

DorpsGek opened this issue Apr 30, 2009 · 4 comments
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flyspray This issue is imported from FlySpray (https://bugs.openttd.org/)

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@DorpsGek
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divide opened the ticket and wrote:

Sometimes when AI is presumably trying to build a tunnel, OpenTTD segfaults with message:

openttd: /home/divide/projekty/openttd/src/ai/api/../../map_func.h:347: TileIndexDiff TileOffsByDiagDir(DiagDirection): Assertion `IsValidDiagDirection(dir)' failed.

I haven't got time to make an isolated testcase and haven't even pinpointed which AI is the culprit; I'm attaching a savegame (quite complex, alas, with several AIs and NewGRFs) that showcases the problem (just have it run for ca 2 minutes on fast forward). Having said that, attached patch fixes it and seems harmless otherwise.

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Reported version: trunk
Operating system: All

This issue was imported from FlySpray: https://bugs.openttd.org/task/2875
@DorpsGek
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frosch wrote:

The issue is

::DoCommand(tile, 0, 0, DC_AUTO, CMD_BUILD_TUNNEL);

failing in AITunnel::GetOtherTunnelEnd.

The function should also work, when start/endtile cannot be bulldozed/excavated or the rail-/road-type is not available.

This comment was imported from FlySpray: https://bugs.openttd.org/task/2875#comment6003

@DorpsGek
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DorpsGek commented May 1, 2009

divide wrote:

Actually it's failing in AITunnel::_BuildTunnelRoad1(). Here's the backtrace:

# 0 AITunnel::_BuildTunnelRoad1 () at /home/divide/projekty/openttd/src/ai/api/ai_tunnel.cpp:90
# 1 0x080eadce in AITunnel::BuildTunnel (vehicle_type=AIVehicle::VT_ROAD, start=37209)
at /home/divide/projekty/openttd/src/ai/api/ai_tunnel.cpp:80
# 2 0x080a3c96 in SQConvert::HelperT<bool ()(AIVehicle::VehicleType, unsigned int), false>::SQCall (instance=0x0,
func=0x80eac80 <AITunnel::BuildTunnel(AIVehicle::VehicleType, unsigned int)>, vm=0x879d540)
at /home/divide/projekty/openttd/src/ai/../script/squirrel_helper.hpp:275
# 3 0x080ae33e in SQConvert::DefSQStaticCallback<AITunnel, bool ()(AIVehicle::VehicleType, unsigned int)> (vm=0x879d540)
at /home/divide/projekty/openttd/src/ai/../script/squirrel_helper.hpp:826
# 4 0x080751b1 in SQVM::CallNative (this=0x879d540, nclosure=0x8831198, nargs=3, stackbase=50, retval=@0xbff1ed2c, suspend=@0xbff1ed2b)
at /home/divide/projekty/openttd/src/3rdparty/squirrel/squirrel/sqvm.cpp:1133
# 5 0x08076f37 in SQVM::Execute (this=0x879d540, closure=@0x8437240, target=69, nargs=-1, stackbase=-1, outres=@0xbff1ee18, raiseerror=1,
et=ET_RESUME_OPENTTD) at /home/divide/projekty/openttd/src/3rdparty/squirrel/squirrel/sqvm.cpp:752
# 6 0x0804dd31 in sq_resumecatch (v=0x879d540, suspend=10000) at /home/divide/projekty/openttd/src/3rdparty/squirrel/squirrel/sqapi.cpp:1005
# 7 0x08246eb1 in Squirrel::Resume (this=0x861d0d8, suspend=10000) at /home/divide/projekty/openttd/src/script/squirrel.cpp:179
# 8 0x08089b34 in AIInstance::GameLoop (this=0x86e5098) at /home/divide/projekty/openttd/src/ai/ai_instance.cpp:322
# 9 0x08080d7f in AI::GameLoop () at /home/divide/projekty/openttd/src/ai/ai_core.cpp:69
# 10 0x081e43d4 in StateGameLoop () at /home/divide/projekty/openttd/src/openttd.cpp:1113
# 11 0x081e5707 in GameLoop () at /home/divide/projekty/openttd/src/openttd.cpp:1193
# 12 0x082cfd38 in VideoDriver_SDL::MainLoop (this=0x85c3968) at /home/divide/projekty/openttd/src/video/sdl_v.cpp:498
# 13 0x081e6279 in ttd_main (argc=2, argv=0xbff1f394) at /home/divide/projekty/openttd/src/openttd.cpp:692
# 14 0x082b9ad5 in main (argc=2, argv=0xbff1f394) at /home/divide/projekty/openttd/src/unix.cpp:251

GetOtherTunnelEnd is fine (otherwise my fix would've segfaulted too).

This comment was imported from FlySpray: https://bugs.openttd.org/task/2875#comment6004

@DorpsGek
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DorpsGek commented May 1, 2009

divide wrote:

(I've just noticed that the backtrace is from just before the segfault. It happens on line 92, because of dir_1 being DIAGDIR_INVALID, because of end being TILE_INVALID.)

This comment was imported from FlySpray: https://bugs.openttd.org/task/2875#comment6005

@DorpsGek
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DorpsGek commented May 6, 2009

Yexo closed the ticket.

Reason for closing: Fixed

In r16243.

This comment was imported from FlySpray: https://bugs.openttd.org/task/2875

@DorpsGek DorpsGek closed this as completed May 6, 2009
@DorpsGek DorpsGek added NewAI flyspray This issue is imported from FlySpray (https://bugs.openttd.org/) labels Apr 6, 2018
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