[Freeciv-Dev] Re: (PR#10567) pubserver crash: ai-controlled unit has no goto destination

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=10567 >

The role is ATTACK or DEFEND_HOME, but there is no goto destination set. 
  So there's a crash.

Does this mean the unit has arrived?  For instance with DEFEND_HOME once 
we get there isn't the goto_dest cleared?  In this case should we be 
looking at the current tile?  Or should we not have cleared the goto 
dest?  Or is a special case needed for DEFEND_HOME?

This patch avoids the crash but may still be buggy.  If the goto dest is 
null it's treated as the success case.  However this may mean a unit can 
get locked into this role.  I dunno.

jason


? fctest
? freeciv-2.0.0-beta1.tar.gz
Index: ai/aidiplomat.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/ai/aidiplomat.c,v
retrieving revision 1.40
diff -u -r1.40 aidiplomat.c
--- ai/aidiplomat.c     29 Sep 2004 02:24:18 -0000      1.40
+++ ai/aidiplomat.c     16 Oct 2004 21:48:27 -0000
@@ -574,7 +574,12 @@
       || punit->ai.ai_role == AIUNIT_DEFEND_HOME) {
     bool failure = FALSE;
 
-    ctarget = map_get_city(punit->goto_tile);
+    /* In rare cases the goto tile may be NULL at this point.  It's
+     * probably a bug... */
+#ifdef DEBUG
+    assert(punit->goto_tile != NULL);
+#endif
+    ctarget = punit->goto_tile ? punit->goto_tile->city : NULL;
     if (pf_get_position(map, punit->goto_tile, &pos)
         && ctarget) {
       if (same_pos(ctarget->tile, punit->tile)) {