From 5869f790d8e926e8b906de91a7aefec29763d579 Mon Sep 17 00:00:00 2001 From: Peter Nelson Date: Tue, 3 Oct 2023 12:14:32 +0100 Subject: [PATCH] Fix: Check for engine variant loops during NewGRF initialization. (#11343) Invalid NewGRFs could set up an engine variant loop that never ends. This was checked for in some places that evaluated variants, but not all. In most cases this would result in the engines not appearing, but could potentially cause an infinite loop and crash. Instead, during NewGRF initialization detect loops and remove invalid variants before setting display flags. --- src/build_vehicle_gui.cpp | 11 ++++++----- src/engine.cpp | 6 +++--- src/newgrf.cpp | 25 +++++++++++++++++++++---- 3 files changed, 30 insertions(+), 12 deletions(-) diff --git a/src/build_vehicle_gui.cpp b/src/build_vehicle_gui.cpp index 6c5e5223e3..9c869426e5 100644 --- a/src/build_vehicle_gui.cpp +++ b/src/build_vehicle_gui.cpp @@ -1422,7 +1422,7 @@ struct BuildVehicleWindow : Window { list.emplace_back(eid, e->info.variant_id, e->display_flags, 0); if (rvi->railveh_type != RAILVEH_WAGON) num_engines++; - if (e->info.variant_id != eid && e->info.variant_id != INVALID_ENGINE) variants.push_back(e->info.variant_id); + if (e->info.variant_id != INVALID_ENGINE) variants.push_back(e->info.variant_id); if (eid == this->sel_engine) sel_id = eid; } @@ -1654,13 +1654,14 @@ struct BuildVehicleWindow : Window { Command::Post(GetCmdBuildVehMsg(this->vehicle_type), CcBuildPrimaryVehicle, this->window_number, sel_eng, true, cargo, INVALID_CLIENT_ID); } - /* Update last used variant and refresh if necessary. */ + /* Update last used variant in hierarchy and refresh if necessary. */ bool refresh = false; - int recursion = 10; /* In case of infinite loop */ - for (Engine *e = Engine::Get(sel_eng); recursion > 0; e = Engine::Get(e->info.variant_id), --recursion) { + EngineID parent = sel_eng; + while (parent != INVALID_ENGINE) { + Engine *e = Engine::Get(parent); refresh |= (e->display_last_variant != sel_eng); e->display_last_variant = sel_eng; - if (e->info.variant_id == INVALID_ENGINE) break; + parent = e->info.variant_id; } if (refresh) { InvalidateWindowData(WC_REPLACE_VEHICLE, this->vehicle_type, 0); // Update the autoreplace window diff --git a/src/engine.cpp b/src/engine.cpp index 3aa242e375..50ae4606b3 100644 --- a/src/engine.cpp +++ b/src/engine.cpp @@ -491,7 +491,7 @@ bool Engine::IsVariantHidden(CompanyID c) const * the last display variant rather than the actual parent variant. */ const Engine *re = this; const Engine *ve = re->GetDisplayVariant(); - while (!(ve->IsHidden(c)) && re->info.variant_id != INVALID_ENGINE && re->info.variant_id != re->index) { + while (!(ve->IsHidden(c)) && re->info.variant_id != INVALID_ENGINE) { re = Engine::Get(re->info.variant_id); ve = re->GetDisplayVariant(); } @@ -607,7 +607,7 @@ void CalcEngineReliability(Engine *e, bool new_month) { /* Get source engine for reliability age. This is normally our engine unless variant reliability syncing is requested. */ Engine *re = e; - while (re->info.variant_id != INVALID_ENGINE && re->info.variant_id != re->index && (re->info.extra_flags & ExtraEngineFlags::SyncReliability) != ExtraEngineFlags::None) { + while (re->info.variant_id != INVALID_ENGINE && (re->info.extra_flags & ExtraEngineFlags::SyncReliability) != ExtraEngineFlags::None) { re = Engine::Get(re->info.variant_id); } @@ -706,7 +706,7 @@ void StartupOneEngine(Engine *e, TimerGameCalendar::Date aging_date, uint32_t se /* Get parent variant index for syncing reliability via random seed. */ const Engine *re = e; - while (re->info.variant_id != INVALID_ENGINE && re->info.variant_id != re->index && (re->info.extra_flags & ExtraEngineFlags::SyncReliability) != ExtraEngineFlags::None) { + while (re->info.variant_id != INVALID_ENGINE && (re->info.extra_flags & ExtraEngineFlags::SyncReliability) != ExtraEngineFlags::None) { re = Engine::Get(re->info.variant_id); } diff --git a/src/newgrf.cpp b/src/newgrf.cpp index a89addfcc4..228832dc2d 100644 --- a/src/newgrf.cpp +++ b/src/newgrf.cpp @@ -9125,12 +9125,9 @@ static void FinaliseEngineArray() } } - /* Do final mapping on variant engine ID and set appropriate flags on variant engine */ + /* Do final mapping on variant engine ID. */ if (e->info.variant_id != INVALID_ENGINE) { e->info.variant_id = GetNewEngineID(e->grf_prop.grffile, e->type, e->info.variant_id); - if (e->info.variant_id != INVALID_ENGINE) { - Engine::Get(e->info.variant_id)->display_flags |= EngineDisplayFlags::HasVariants | EngineDisplayFlags::IsFolded; - } } if (!HasBit(e->info.climates, _settings_game.game_creation.landscape)) continue; @@ -9162,6 +9159,26 @@ static void FinaliseEngineArray() } } } + + /* Check engine variants don't point back on themselves (either directly or via a loop) then set appropriate flags + * on variant engine. This is performed separately as all variant engines need to have been resolved. */ + for (Engine *e : Engine::Iterate()) { + EngineID parent = e->info.variant_id; + while (parent != INVALID_ENGINE) { + parent = Engine::Get(parent)->info.variant_id; + if (parent != e->index) continue; + + /* Engine looped back on itself, so clear the variant. */ + e->info.variant_id = INVALID_ENGINE; + + GrfMsg(1, "FinaliseEngineArray: Variant of engine {:x} in '{}' loops back on itself", _engine_mngr[e->index].internal_id, e->GetGRF()->filename); + break; + } + + if (e->info.variant_id != INVALID_ENGINE) { + Engine::Get(e->info.variant_id)->display_flags |= EngineDisplayFlags::HasVariants | EngineDisplayFlags::IsFolded; + } + } } /** Check for invalid cargoes */