Fix segfaults in AI code

src/AIModel/AIAircraft.cxx

@@ -348,7 +348,11 @@ void FGAIAircraft::ProcessFlightPlan( double dt, time_t now ) {
         }
     }
     if (!curr) {
-        SG_LOG(SG_AI, SG_WARN, "No current WP" << next->getName());
+        if (!next) {
+            SG_LOG(SG_AI, SG_WARN, getCallSign() << "|No more WPs");
+        } else {
+            SG_LOG(SG_AI, SG_WARN, getCallSign() << "|No current WP" << next->getName());
+        }
         return;
     }
 
@@ -1016,6 +1020,8 @@ bool FGAIAircraft::handleAirportEndPoints(FGAIWaypoint* prev, time_t now) {
 
     if (!( dep && arr))
         return false;
+    if (!prev)
+        return false;
 
     // This waypoint marks the fact that the aircraft has passed the initial taxi
     // departure waypoint, so it can release the parking.
@@ -1471,17 +1477,25 @@ bool FGAIAircraft::reachedEndOfCruise(double &distance) {
 
 void FGAIAircraft::resetPositionFromFlightPlan()
 {
+    if (fp->empty()) {
+        return;
+    }
     // the one behind you
-    FGAIWaypoint* prev = 0;
+    FGAIWaypoint* prev = nullptr;
     // the one ahead
-    FGAIWaypoint* curr = 0;
+    FGAIWaypoint* curr = nullptr;
     // the next plus 1
-    FGAIWaypoint* next = 0;
+    FGAIWaypoint* next = nullptr;
 
     prev = fp->getPreviousWaypoint();
     curr = fp->getCurrentWaypoint();
     next = fp->getNextWaypoint();
 
+    if (curr==nullptr || next==nullptr) {
+        SG_LOG(SG_AI, SG_WARN, getCallSign() << "|Repositioned without curr/next");
+        return;
+    }
+
     setLatitude(prev->getLatitude());
     setLongitude(prev->getLongitude());
     setHeading(fp->getBearing(curr, next));

src/AIModel/AIFlightPlan.cxx

@@ -548,6 +548,9 @@ void FGAIFlightPlan::addWaypoint(FGAIWaypoint* wpt)
 
 void FGAIFlightPlan::pushBackWaypoint(FGAIWaypoint *wpt)
 {
+  if (!wpt) {
+    SG_LOG(SG_AI, SG_WARN, "Null WPT added");
+  }
   size_t pos = wpt_iterator - waypoints.begin();
   if (waypoints.size()>0) {
       double dist = SGGeodesy::distanceM( waypoints.back()->getPos(), wpt->getPos());
@@ -587,7 +590,10 @@ double FGAIFlightPlan::checkTrackLength(const string& wptName) const {
     wpt_vector_iterator wptvec = waypoints.begin();
     ++wptvec;
     ++wptvec;
-    while ((wptvec != waypoints.end()) && (!((*wptvec)->contains(wptName)))) {
+    while ((wptvec != waypoints.end())) {
+      if (*wptvec!=nullptr && (!((*wptvec)->contains(wptName)))) {
+        break;
+      }
       trackDistance += (*wptvec)->getTrackLength();
       ++wptvec;
     }

src/AIModel/AIFlightPlan.hxx

@@ -33,19 +33,19 @@ class SGPath;
 
 class FGAIWaypoint {
   private:
-   std::string name;
+    std::string name = "unnamed";
     SGGeod pos;
-   double speed;
-   double crossat;
-   bool finished;
-   bool gear_down;
-   double flaps;
+    double speed = 0.0;
+    double crossat = 0.0;
+    bool finished = false;
+    bool gear_down = true;
+    double flaps = 0.0;
     double spoilers = 0.0;
     double speedbrakes = 0.0;
     bool on_ground;
     int routeIndex;  // For AI/ATC purposes;
     double time_sec;
-   double trackLength; // distance from previous FGAIWaypoint (for AI purposes);
+    double trackLength = 0.0; // distance from previous FGAIWaypoint (for AI purposes);
     std::string time;
 
     bool beacon_light = false;

src/AIModel/AIFlightPlanCreate.cxx

@@ -117,10 +117,20 @@ bool FGAIFlightPlan::create(FGAIAircraft * ac, FGAirport * dep,
                " this is probably an internal program error");
         break;
     }
-    wpt_iterator = waypoints.begin() + currWpt;
     //don't  increment leg right away, but only once we pass the actual last waypoint that was created.
     // to do so, mark the last waypoint with a special status flag
     if (retVal) {
+        if (waypoints.empty()) {
+            SG_LOG(SG_AI, SG_WARN, ac->getCallSign() << "|AIFlightPlan::create() Leg "  << legNr <<
+                " created empty waypoints." );
+            return retVal;
+        }
+        wpt_iterator = waypoints.begin() + currWpt;
+        if (waypoints.back()->getName().size()==0) {
+            SG_LOG(SG_AI, SG_WARN, ac->getCallSign() <<
+                " Empty wpt name");
+
+        }
         waypoints.back()->setName( waypoints.back()->getName() + string("legend"));
         // "It's pronounced Leg-end" (Roger Glover (Deep Purple): come Hell or High Water DvD, 1993)
     }
@@ -1029,8 +1039,10 @@ bool FGAIFlightPlan::createDescent(FGAIAircraft * ac, FGAirport * apt,
         ac->resetPositionFromFlightPlan();
     }
 
-    SG_LOG(SG_AI, SG_BULK, "Setting Node " << waypoints[1]->getName() << " to a leg end");
-    waypoints[1]->setName( (waypoints[1]->getName() + string("legend")));
+    if (!waypoints.empty()) {
+        SG_LOG(SG_AI, SG_BULK, "Setting Node " << waypoints.back()->getName() << " to a leg end");
+        waypoints.back()->setName( (waypoints.back()->getName() + string("legend")));
+    }
 
     return true;
 }

src/AIModel/AIFlightPlanCreateCruise.cxx

@@ -287,7 +287,8 @@ bool FGAIFlightPlan::createCruise(FGAIAircraft *ac, bool firstFlight, FGAirport
                   FGAirport *arr,
                   const SGGeod& current,
                   double speed,
-                  double alt, const string& fltType)
+                  double alt,
+                  const string& fltType)
 {
   double vCruise = ac->getPerformance()->vCruise();
   FGAIWaypoint *wpt;
@@ -305,6 +306,7 @@ bool FGAIFlightPlan::createCruise(FGAIAircraft *ac, bool firstFlight, FGAirport
   double heading = ac->getTrafficRef()->getCourse();
   arr->getDynamics()->getActiveRunway(rwyClass, 2, activeRunway, heading);
   if (!arr->hasRunwayWithIdent(activeRunway)) {
+    SG_LOG(SG_AI, SG_WARN, ac->getCallSign() << " cruise to" << arr->getId() << activeRunway << " not active");
     return false;
   }
 

src/Airports/groundnetwork.cxx

@@ -483,10 +483,10 @@ FGTaxiRoute FGGroundNetwork::findShortestRoute(FGTaxiNode* start, FGTaxiNode* en
 
     if (searchData[end].score == HUGE_VAL) {
         // no valid route found
-        if (fullSearch) {
+        if (fullSearch && start && end) {
             SG_LOG(SG_GENERAL, SG_ALERT,
-                   "Failed to find route from waypoint " << start << " to "
-                   << end << " at " << parent->getId());
+                   "Failed to find route from waypoint " << start->getIndex() << " to "
+                   << end->getIndex() << " at " << parent->getId());
         }
 
         return FGTaxiRoute();