Remove crash bug when purging a dropped item in a wtrigger.

We're leveraging the lookup table, because it's a safer way
to see if an object has been free'd than looking at the object
itself (which while it may work may just as well fail).

Fixes #83

src/act.item.c

@@ -52,11 +52,12 @@ static void wear_message(struct char_data *ch, struct obj_data *obj, int where);
 
 static void perform_put(struct char_data *ch, struct obj_data *obj, struct obj_data *cont)
 {
+  long object_id = obj_script_id(obj);
 
   if (!drop_otrigger(obj, ch))
     return;
 
-  if (!obj) /* object might be extracted by drop_otrigger */
+  if (!has_obj_by_uid_in_lookup_table(object_id)) /* object might be extracted by drop_otrigger */
     return;
 
   if ((GET_OBJ_VAL(cont, 0) > 0) &&
@@ -416,9 +417,12 @@ static void perform_drop_gold(struct char_data *ch, int amount, byte mode, room_
 	      act("$p suddenly appears in a puff of orange smoke!", 0, 0, obj, 0, TO_ROOM);
       } else {
         char buf[MAX_STRING_LENGTH];
+        long object_id = obj_script_id(obj);
 
         if (!drop_wtrigger(obj, ch)) {
+          if (has_obj_by_uid_in_lookup_table(object_id))
             extract_obj(obj);
+
           return;
         }
 
@@ -447,13 +451,20 @@ static int perform_drop(struct char_data *ch, struct obj_data *obj,
 {
   char buf[MAX_STRING_LENGTH];
   int value;
+  long object_id = obj_script_id(obj);
 
   if (!drop_otrigger(obj, ch))
     return 0;
 
+  if (!has_obj_by_uid_in_lookup_table(object_id))
+    return 0; // item was extracted by script
+
   if ((mode == SCMD_DROP) && !drop_wtrigger(obj, ch))
     return 0;
 
+  if (!has_obj_by_uid_in_lookup_table(object_id))
+    return 0; // item was extracted by script
+
   if (OBJ_FLAGGED(obj, ITEM_NODROP) && !PRF_FLAGGED(ch, PRF_NOHASSLE)) {
     snprintf(buf, sizeof(buf), "You can't %s $p, it must be CURSED!", sname);
     act(buf, FALSE, ch, obj, 0, TO_CHAR);

src/dg_scripts.c

@@ -2994,12 +2994,18 @@ void init_lookup_table(void)
   }
 }
 
-static struct char_data *find_char_by_uid_in_lookup_table(long uid)
+static struct lookup_table_t *find_element_by_uid_in_lookup_table(long uid)
 {
   int bucket = (int) (uid & (BUCKET_COUNT - 1));
   struct lookup_table_t *lt = &lookup_table[bucket];
 
   for (;lt && lt->uid != uid ; lt = lt->next) ;
+  return lt;
+}
+
+static struct char_data *find_char_by_uid_in_lookup_table(long uid)
+{
+  struct lookup_table_t *lt = find_element_by_uid_in_lookup_table(uid);
 
   if (lt)
     return (struct char_data *)(lt->c);
@@ -3010,10 +3016,7 @@ static struct char_data *find_char_by_uid_in_lookup_table(long uid)
 
 static struct obj_data *find_obj_by_uid_in_lookup_table(long uid)
 {
-  int bucket = (int) (uid & (BUCKET_COUNT - 1));
+  struct lookup_table_t *lt = find_element_by_uid_in_lookup_table(uid);
-  struct lookup_table_t *lt = &lookup_table[bucket];
-
-  for (;lt && lt->uid != uid ; lt = lt->next) ;
 
   if (lt)
     return (struct obj_data *)(lt->c);
@@ -3022,6 +3025,13 @@ static struct obj_data *find_obj_by_uid_in_lookup_table(long uid)
   return NULL;
 }
 
+int has_obj_by_uid_in_lookup_table(long uid)
+{
+  struct lookup_table_t *lt = find_element_by_uid_in_lookup_table(uid);
+
+  return lt != NULL;
+}
+
 void add_to_lookup_table(long uid, void *c)
 {
   int bucket = (int) (uid & (BUCKET_COUNT - 1));
@@ -3054,9 +3064,7 @@ void remove_from_lookup_table(long uid)
   if (uid == 0)
     return;
 
-  for (;lt;lt = lt->next)
+  flt = find_element_by_uid_in_lookup_table(uid);
-    if (lt->uid == uid)
-      flt = lt;
 
   if (flt) {
     for (lt = &lookup_table[bucket];lt->next != flt;lt = lt->next)

src/dg_scripts.h

@@ -449,6 +449,8 @@ void wld_command_interpreter(room_data *room, char *argument);
 // id helpers
 extern long char_script_id(char_data *ch);
 extern long obj_script_id(obj_data *obj);
+extern int has_obj_by_uid_in_lookup_table(long uid);
+
 #define room_script_id(room)  ((long)(room)->number + ROOM_ID_BASE)
 
 #endif /* _DG_SCRIPTS_H_ */