Provide access to modules

With the provided functions it is possible to iterate over all loaded
modules or over all modules of a specific type.

include/maxscale/modules.h

@@ -121,4 +121,44 @@ void module_feedback_send(void*);
  */
 void moduleShowFeedbackReport(DCB *dcb);
 
+typedef struct mxs_module_iterator
+{
+    const char* type;
+    void* position;
+} MXS_MODULE_ITERATOR;
+
+/**
+ * @brief Returns an iterator to modules.
+ *
+ * @attention It is unspecified whether a module loaded after the iterator
+ *            was created, will be returned by the iterator. The behaviour
+ *            is undefined if a module is unloaded while an iteration is
+ *            being performed.
+ *
+ * @param type  The type of modules that should be returned. If NULL,
+ *              then all modules are returned.
+ *
+ * @return An iterator.
+ */
+MXS_MODULE_ITERATOR mxs_module_iterator_get(const char* type);
+
+/**
+ * @brief Indicates whether the iterator has a module to return.
+ *
+ * @param iterator  An iterator
+ *
+ * @return True if a subsequent call to @c mxs_module_iterator_get
+ *         will return a module.
+ */
+bool mxs_module_iterator_has_next(const MXS_MODULE_ITERATOR* iterator);
+
+/**
+ * @brief Returns the next module and advances the iterator.
+ *
+ * @param iterator  An iterator.
+ *
+ * @return A module if there was a module to return, NULL otherwise.
+ */
+MXS_MODULE* mxs_module_iterator_get_next(MXS_MODULE_ITERATOR* iterator);
+
 MXS_END_DECLS

server/core/load_utils.c

@@ -849,3 +849,45 @@ const MXS_MODULE *get_module(const char *name, const char *type)
 
     return mod ? mod->info : NULL;
 }
+
+MXS_MODULE_ITERATOR mxs_module_iterator_get(const char* type)
+{
+    LOADED_MODULE* module = registered;
+
+    while (module && type && (strcmp(module->type, type) != 0))
+    {
+        module = module->next;
+    }
+
+    MXS_MODULE_ITERATOR iterator;
+    iterator.type = type;
+    iterator.position = module;
+
+    return iterator;
+}
+
+bool mxs_module_iterator_has_next(const MXS_MODULE_ITERATOR* iterator)
+{
+    return iterator->position != NULL;
+}
+
+MXS_MODULE* mxs_module_iterator_get_next(MXS_MODULE_ITERATOR* iterator)
+{
+    MXS_MODULE* module = NULL;
+    LOADED_MODULE* loaded_module = (LOADED_MODULE*)iterator->position;
+
+    if (loaded_module)
+    {
+        module = loaded_module->info;
+
+        do
+        {
+            loaded_module = loaded_module->next;
+        }
+        while (loaded_module && iterator->type && (strcmp(loaded_module->type, iterator->type) != 0));
+
+        iterator->position = loaded_module;
+    }
+
+    return module;
+}