[Freeciv-Dev] (PR#9877) Reproducable crash with Freeciv compiled from current CVS HEAD (20040830 1700 UTC)

["Mateusz Stefek" <mstefek@xxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=9877 >

> [tim.kosse@xxxxxx - Mon Aug 30 18:42:46 2004]:
> 
> Hi,
> 
> testing current CVS Version, Freeciv did crash very frequently. The 
> location of the crash changed each time.
> 
> I did run valgrind --tool=memcheck on the server and valgrind did output 
> the following reproducable:
> 
> Invalid write of size 1
>    ai_data_turn_init (aidata.c:101)
>    begin_phase (srv_main.c:489)
>    main_loop (srv_main.c:1430)
>    srv_main (srv_main.c:1549)
> Address 0x1BB13125 is 13 bytes after a block of size 24 alloc'd
>    malloc (vb_replace_malloc.c:131)
>    fc_real_malloc (mem.c:79)
>    create_danger_segment (path_finding.c:730)
>    danger_iterate_map (path_finding.c:897)
> 
> The line in question in aidata.c is:
> ai->threats.ocean[-continent] = TRUE;
> 
> I did add some debugging code around it, the value of continent is -1 
> when valgrind reports the problem.
> 
> So obviously the ai code is writing to the wrong memory location 
> somehow. Unfortunately I'm not familiar enough with the freeciv code to 
> fix this and submit a patch.
> 
> I've attached a savegame which shows the problem. After loading it, just 
> fortify all active units. When the round ends, valgrind will show the 
> error message. If not using valgrind, Freeciv will crash afterwards with 
> a high percentage.
> 
> Regards,
> Tim Kosse

That's because silly ai code assumes that a sailing unit is on an ocean
tile when creating danger tables. Patch attached.
I'm applying it immedietely.
--
mateusz

Index: aidata.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/ai/aidata.c,v
retrieving revision 1.34
diff -u -r1.34 aidata.c
--- aidata.c    29 Aug 2004 19:43:37 -0000      1.34
+++ aidata.c    30 Aug 2004 20:44:51 -0000
@@ -97,9 +97,13 @@
         /* The idea is that while our enemies don't have any offensive
          * seaborne units, we don't have to worry. Go on the offensive! */
         if (unit_type(punit)->attack_strength > 1) {
-          Continent_id continent = map_get_continent(punit->x, punit->y);
-          ai->threats.ocean[-continent] = TRUE;
-        }
+         square_iterate(punit->x, punit->y, 1, x2, y2) {
+           if (is_ocean(map_get_terrain(x2, y2))) {
+             Continent_id continent = map_get_continent(x2, y2);
+             ai->threats.ocean[-continent] = TRUE;
+           }
+         } square_iterate_end;
+        } 
         continue;
       }