cfg_get_group_*() is introduced:

  returns the list of declared groups

cfg_diff_*() is introduced:
  returns the pending configuration changes

cfg/cfg_ctx.c

@@ -783,3 +783,113 @@ int cfg_help(cfg_ctx_t *ctx, str *group_name, str *var_name,
 	*ch = var->def->descr;
 	return 0;
 }
+
+/* return the group name and the cfg structure definition,
+ * and moves the handle to the next group
+ * Return value:
+ *	0: no more group
+ *	1: group exists
+ */
+int cfg_get_group_next(void **h,
+			str *gname, cfg_def_t **def)
+{
+	cfg_group_t	*group;
+
+	group = (cfg_group_t *)(*h);
+	if (group == NULL) return 0;
+
+	gname->s = group->name;
+	gname->len = group->name_len;
+	(*def) = group->mapping->def;
+
+	(*h) = (void *)group->next;
+	return 1;
+}
+
+/* Initialize the handle for cfg_diff_next() */
+int cfg_diff_init(cfg_ctx_t *ctx,
+		void **h)
+{
+	if (!ctx) {
+		LOG(L_ERR, "ERROR: cfg_diff_init(): context is undefined\n");
+		return -1;
+	}
+
+	CFG_CTX_LOCK(ctx);
+	(*h) = (void *)ctx->changed_first;
+
+	return 0;
+}
+
+/* return the pending changes that have not been
+ * committed yet
+ */
+int cfg_diff_next(void **h,
+			str *gname, str *vname,
+			void **old_val, void **new_val,
+			unsigned int *val_type)
+{
+	cfg_changed_var_t	*changed;
+	void	*p;
+	static str	old_s, new_s;	/* we need the value even
+					after the function returns */
+	int		i;
+	char		*ch;
+
+	changed = (cfg_changed_var_t *)(*h);
+	if (changed == NULL) return 0;
+
+	gname->s = changed->group->name;
+	gname->len = changed->group->name_len;
+	vname->s = changed->var->def->name;
+	vname->len = changed->var->name_len;
+
+	/* use the module's handle to access the variable
+	It means that the variable is read from the local config
+	after forking */
+	p = *(changed->group->handle) + changed->var->offset;
+
+	switch (CFG_VAR_TYPE(changed->var)) {
+	case CFG_VAR_INT:
+		memcpy(&i, p, sizeof(int));
+		*old_val = (void *)(long)i;
+		memcpy(&i, changed->new_val, sizeof(int));
+		*new_val = (void *)(long)i;
+		break;
+
+	case CFG_VAR_STRING:
+		memcpy(&ch, p, sizeof(char *));
+		*old_val = (void *)ch;
+		memcpy(&ch, changed->new_val, sizeof(char *));
+		*new_val = (void *)ch;
+		break;
+
+	case CFG_VAR_STR:
+		memcpy(&old_s, p, sizeof(str));
+		*old_val = (void *)&old_s;
+		memcpy(&new_s, changed->new_val, sizeof(str));
+		*new_val = (void *)&new_s;
+		break;
+
+	case CFG_VAR_POINTER:
+		memcpy(old_val, &p, sizeof(void *));
+		memcpy(new_val, &changed->new_val, sizeof(void *));
+		break;
+
+	}
+	*val_type = CFG_VAR_TYPE(changed->var);
+
+	(*h) = (void *)changed->next;
+	return 1;
+}
+
+/* release the handle of cfg_diff_next() */
+void cfg_diff_release(cfg_ctx_t *ctx)
+{
+	if (!ctx) {
+		LOG(L_ERR, "ERROR: cfg_diff_release(): context is undefined\n");
+		return;
+	}
+
+	CFG_CTX_UNLOCK(ctx);
+}

cfg/cfg_ctx.h

@@ -106,5 +106,55 @@ int cfg_help(cfg_ctx_t *ctx, str *group_name, str *var_name,
 /* notify the drivers about the new config definition */
 void cfg_notify_drivers(char *group_name, cfg_def_t *def);
 
+/* initialize the handle for cfg_get_group_next() */
+#define cfg_get_group_init(handle) \
+	(*(handle)) = (void *)cfg_group
+
+/* returns the group name and the cfg structure definition,
+ * and moves the handle to the next group
+ * Return value:
+ *	0: no more group
+ *	1: group exists
+ *
+ * can be used as follows:
+ *
+ * void	*handle;
+ * cfg_get_group_init(&handle)
+ * while (cfg_get_group_next(&handle, &name, &def)) {
+ * 	...
+ * }
+ */
+int cfg_get_group_next(void **h,
+			str *gname, cfg_def_t **def);
+
+/* Initialize the handle for cfg_diff_next()
+ * WARNING: keeps the context lock held, do not forget
+ * to release it with cfg_diff_release()
+ */
+int cfg_diff_init(cfg_ctx_t *ctx,
+		void **h);
+
+/* return the pending changes that have not been
+ * committed yet
+ * can be used as follows:
+ *
+ * void *handle;
+ * if (cfg_diff_init(ctx, &handle)) return -1
+ * while (cfg_diff_next(&handle
+ *			&group_name, &var_name,
+ *			&old_val, &new_val
+ *			&val_type)
+ * ) {
+ *		...
+ * }
+ * cfg_diff_release(ctx);
+ */
+int cfg_diff_next(void **h,
+			str *gname, str *vname,
+			void **old_val, void **new_val,
+			unsigned int *val_type);
+
+/* destroy the handle of cfg_diff_next() */
+void cfg_diff_release(cfg_ctx_t *ctx);
 
 #endif /* _CFG_CTX_H */

doc/cfg.txt

@@ -239,6 +239,38 @@ cfg_rollback()
 
 cfg_help()
 
+-------------------------------------------------------------------------------
+
+7. Get the list of group definitions:
+
+void	*h;
+str	gname;
+cfg_def_t	*def;
+
+cfg_get_group_init(&h);
+while(cfg_get_group_next(&h, &gname, &def)) {
+	...
+}
+
+-------------------------------------------------------------------------------
+
+8. Get the list of pending changes that have not been committed yet:
+
+void		*h;
+str		gname, vname;
+void		*old_val, *new_val;
+unsigned int	val_type;
+
+if (cfg_diff_init(ctx, &h)) return -1;
+while(cfg_diff_next(&h,
+		&gname, &vname,
+		&old_val, &new_val,
+		&val_type)
+) {
+	...
+}
+cfg_diff_release(ctx);
+
 
 5. Refreshing the configuration
 ===============================================================================