Add wmem_map_steal

Mimic functionality of g_hash_table_steal

Change-Id: Iaf4aeef951b60934569143b2d119f782aeefe380
Reviewed-on: https://code.wireshark.org/review/20038
Reviewed-by: Michael Mann <mmann78@netscape.net>

debian/libwireshark0.symbols

@@ -1794,6 +1794,7 @@ libwireshark.so.0 libwireshark0 #MINVER#
  wmem_map_new_autoreset@Base 2.3.0
  wmem_map_remove@Base 1.12.0~rc1
  wmem_map_size@Base 2.1.0
+ wmem_map_steal@Base 2.3.0
  wmem_memdup@Base 1.12.0~rc1
  wmem_packet_scope@Base 1.9.1
  wmem_realloc@Base 1.9.1

epan/wmem/wmem_map.c

@@ -293,6 +293,35 @@ wmem_map_remove(wmem_map_t *map, const void *key)
     return NULL;
 }
 
+gboolean
+wmem_map_steal(wmem_map_t *map, const void *key)
+{
+    wmem_map_item_t **item, *tmp;
+
+    /* Make sure we have a table */
+    if (map->table == NULL) {
+        return FALSE;
+    }
+
+    /* get a pointer to the slot */
+    item = &(map->table[HASH(map, key)]);
+
+    /* check the items in that slot */
+    while (*item) {
+        if (map->eql_func(key, (*item)->key)) {
+            /* found it */
+            tmp     = (*item);
+            (*item) = tmp->next;
+            map->count--;
+            return TRUE;
+        }
+        item = &((*item)->next);
+    }
+
+    /* didn't find it */
+    return FALSE;
+}
+
 void
 wmem_map_foreach(wmem_map_t *map, GHFunc foreach_func, gpointer user_data)
 {

epan/wmem/wmem_map.h

@@ -120,6 +120,17 @@ WS_DLL_PUBLIC
 void *
 wmem_map_remove(wmem_map_t *map, const void *key);
 
+/** Remove a key and value from the map but does not destroy (free) them. If no
+ * value is stored at that key, nothing happens.
+ *
+ * @param map The map to remove from.
+ * @param key The key of the value to remove.
+ * @return TRUE if key is found FALSE if not.
+ */
+WS_DLL_PUBLIC
+gboolean
+wmem_map_steal(wmem_map_t *map, const void *key);
+
 /** Run a function against all key/value pairs in the map. The order
  * of the calls is unpredictable, since it is based on the internal
  * storage of data.