Re: [gnugo-devel] cvs of 12-10-2004: mkpat crash for mingw version

[Arend Bayer]

Gunnar wrote:
> Teun wrote:
> > Possibly something is not initialized properly, resulting
> > in random results. ElectricFence did not reveal a problem.
> > Can someone run valgrind on mkpat?
> 
> Yes, valgrind does find a problem.

> I assume this means that there's memory read out of bounds. For the
> record this only applies to mainline CVS but not to 3.6-pre2. There is
> no relevant diff in mkpat.c between these versions but after copying
> over the more recent owl_attackpats.dtr from 3.6-pre2 the problem went
> away.

Yes, -fbounds-checking gives an error at the same position. Reverting the
hunk below of arend_7_1.17 makes the problem go away. I have committed
this to CVS.

Teun, I hope your problem should be solved by this.

Arend

 
Index: patterns/dfa.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/patterns/dfa.c,v
retrieving revision 1.37
diff -u -p -r1.37 dfa.c
--- patterns/dfa.c      8 Jun 2004 05:52:25 -0000       1.37
+++ patterns/dfa.c      13 Sep 2004 09:23:07 -0000
@@ -113,20 +113,24 @@ member_att(dfa_t *pdfa, int att, int val
 static int
 union_att(dfa_t *pdfa, dfa_t *pdfa1, int att1, dfa_t *pdfa2, int att2)
 {
-  int att;
-  int att_aux;
+  int att_aux = 0;
+  int att = 0;
+  int save1 = att1;
+  int save2 = att2;
 
+  if (att1 == 0 && att2 == 0)
+    return 0;
   /* copy att1 in att */
-  att = 0;
   while (att1 != 0) {
     pdfa->last_index++;
     if (pdfa->last_index >= pdfa->max_indexes)
       resize_dfa(pdfa, pdfa->max_states, pdfa->max_indexes + DFA_RESIZE_STEP);
     att_aux = pdfa->last_index;
+    if (!att)
+      att = att_aux;
     
     pdfa->indexes[att_aux].val = pdfa1->indexes[att1].val;
-    pdfa->indexes[att_aux].next = att;
-    att = att_aux;
+    pdfa->indexes[att_aux].next = att_aux + 1;
     att1 = pdfa1->indexes[att1].next;
   }
 
@@ -137,13 +141,21 @@ union_att(dfa_t *pdfa, dfa_t *pdfa1, int
       if (pdfa->last_index >= pdfa->max_indexes)
        resize_dfa(pdfa, pdfa->max_states, pdfa->max_indexes + DFA_RESIZE_STEP);
       att_aux = pdfa->last_index;
+      if (!att)
+       att = att_aux;
 
       pdfa->indexes[att_aux].val = pdfa2->indexes[att2].val;
-      pdfa->indexes[att_aux].next = att;
-      att = att_aux;
+      pdfa->indexes[att_aux].next = att_aux + 1;
     }
     att2 = pdfa2->indexes[att2].next;
   }
+  pdfa->indexes[att_aux].next = 0;
+  if (0 && save1 != 0 && save2 != 0) {
+    fprintf(stderr, "Made union of %d and %d at %d.\n", save1, save2, att);
+    dump_dfa(stderr, pdfa);
+    dump_dfa(stderr, pdfa1);
+    dump_dfa(stderr, pdfa2);
+  }
 
   return att;
 }