Allow plugins to depend on each other

The only things that plugins can declare is that they should be run before,
after or never with regard to another plugin.

plugins/uefi/fu-plugin-uefi.c

@@ -30,6 +30,12 @@
 #include "fu-plugin.h"
 #include "fu-plugin-vfuncs.h"
 
+void
+fu_plugin_init (FuPlugin *plugin)
+{
+	fu_plugin_add_rule (plugin, FU_PLUGIN_RULE_RUN_AFTER, "upower");
+}
+
 static fwup_resource *
 fu_plugin_uefi_find (fwup_resource_iter *iter, const gchar *guid_str, GError **error)
 {

src/fu-engine.c

@@ -2661,16 +2661,23 @@ fu_engine_plugin_set_coldplug_delay_cb (FuPlugin *plugin, guint duration, FuEngi
 static gint
 fu_engine_plugin_sort_cb (gconstpointer a, gconstpointer b)
 {
-	FuPlugin *plugin1 = *((FuPlugin **) a);
-	FuPlugin *plugin2 = *((FuPlugin **) b);
-	return g_strcmp0 (fu_plugin_get_name (plugin1),
-			  fu_plugin_get_name (plugin2));
+	FuPlugin **pa = (FuPlugin **) a;
+	FuPlugin **pb = (FuPlugin **) b;
+	if (fu_plugin_get_order (*pa) < fu_plugin_get_order (*pb))
+		return -1;
+	if (fu_plugin_get_order (*pa) > fu_plugin_get_order (*pb))
+		return 1;
+	return 0;
 }
 
 static gboolean
 fu_engine_load_plugins (FuEngine *self, GError **error)
 {
+	FuPlugin *dep;
+	GPtrArray *deps;
 	const gchar *fn;
+	gboolean changes;
+	guint dep_loop_check = 0;
 	g_autoptr(GDir) dir = NULL;
 
 	/* search */
@@ -2745,8 +2752,99 @@ fu_engine_load_plugins (FuEngine *self, GError **error)
 				     g_strdup (fu_plugin_get_name (plugin)),
 				     g_object_ref (plugin));
 	}
-	g_ptr_array_sort (self->plugins, fu_engine_plugin_sort_cb);
 
+	/* order by deps */
+	do {
+		changes = FALSE;
+		for (guint i = 0; i < self->plugins->len; i++) {
+			FuPlugin *plugin = g_ptr_array_index (self->plugins, i);
+			deps = fu_plugin_get_rules (plugin, FU_PLUGIN_RULE_RUN_AFTER);
+			for (guint j = 0; j < deps->len && !changes; j++) {
+				const gchar *plugin_name = g_ptr_array_index (deps, j);
+				dep = fu_engine_get_plugin_by_name (self, plugin_name);
+				if (dep == NULL) {
+					g_debug ("cannot find plugin '%s' "
+						 "requested by '%s'",
+						 plugin_name,
+						 fu_plugin_get_name (plugin));
+					continue;
+				}
+				if (!fu_plugin_get_enabled (dep))
+					continue;
+				if (fu_plugin_get_order (plugin) <= fu_plugin_get_order (dep)) {
+					g_debug ("%s [%u] to be ordered after %s [%u] "
+						 "so promoting to [%u]",
+						 fu_plugin_get_name (plugin),
+						 fu_plugin_get_order (plugin),
+						 fu_plugin_get_name (dep),
+						 fu_plugin_get_order (dep),
+						 fu_plugin_get_order (dep) + 1);
+					fu_plugin_set_order (plugin, fu_plugin_get_order (dep) + 1);
+					changes = TRUE;
+				}
+			}
+		}
+		for (guint i = 0; i < self->plugins->len; i++) {
+			FuPlugin *plugin = g_ptr_array_index (self->plugins, i);
+			deps = fu_plugin_get_rules (plugin, FU_PLUGIN_RULE_RUN_BEFORE);
+			for (guint j = 0; j < deps->len && !changes; j++) {
+				const gchar *plugin_name = g_ptr_array_index (deps, j);
+				dep = fu_engine_get_plugin_by_name (self, plugin_name);
+				if (dep == NULL) {
+					g_debug ("cannot find plugin '%s' "
+						 "requested by '%s'",
+						 plugin_name,
+						 fu_plugin_get_name (plugin));
+					continue;
+				}
+				if (!fu_plugin_get_enabled (dep))
+					continue;
+				if (fu_plugin_get_order (plugin) >= fu_plugin_get_order (dep)) {
+					g_debug ("%s [%u] to be ordered before %s [%u] "
+						 "so promoting to [%u]",
+						 fu_plugin_get_name (plugin),
+						 fu_plugin_get_order (plugin),
+						 fu_plugin_get_name (dep),
+						 fu_plugin_get_order (dep),
+						 fu_plugin_get_order (dep) + 1);
+					fu_plugin_set_order (dep, fu_plugin_get_order (plugin) + 1);
+					changes = TRUE;
+				}
+			}
+		}
+
+		/* check we're not stuck */
+		if (dep_loop_check++ > 100) {
+			g_set_error (error,
+				     FWUPD_ERROR,
+				     FWUPD_ERROR_INTERNAL,
+				     "got stuck in dep loop");
+			return FALSE;
+		}
+	} while (changes);
+
+	/* check for conflicts */
+	for (guint i = 0; i < self->plugins->len; i++) {
+		FuPlugin *plugin = g_ptr_array_index (self->plugins, i);
+		if (!fu_plugin_get_enabled (plugin))
+			continue;
+		deps = fu_plugin_get_rules (plugin, FU_PLUGIN_RULE_CONFLICTS);
+		for (guint j = 0; j < deps->len && !changes; j++) {
+			const gchar *plugin_name = g_ptr_array_index (deps, j);
+			dep = fu_engine_get_plugin_by_name (self, plugin_name);
+			if (dep == NULL)
+				continue;
+			if (!fu_plugin_get_enabled (dep))
+				continue;
+			g_debug ("disabling %s as conflicts with %s",
+				 fu_plugin_get_name (dep),
+				 fu_plugin_get_name (plugin));
+			fu_plugin_set_enabled (dep, FALSE);
+		}
+	}
+
+	/* sort by order */
+	g_ptr_array_sort (self->plugins, fu_engine_plugin_sort_cb);
 	return TRUE;
 }
 

src/fu-plugin-private.h

@@ -39,6 +39,11 @@ void		 fu_plugin_set_supported		(FuPlugin	*plugin,
 							 GPtrArray	*supported_guids);
 void		 fu_plugin_set_smbios			(FuPlugin	*plugin,
 							 FuSmbios	*smbios);
+guint		 fu_plugin_get_order			(FuPlugin	*plugin);
+void		 fu_plugin_set_order			(FuPlugin	*plugin,
+							 guint		 order);
+GPtrArray	*fu_plugin_get_rules			(FuPlugin	*plugin,
+							 FuPluginRule	 rule);
 gboolean	 fu_plugin_open				(FuPlugin	*plugin,
 							 const gchar	*filename,
 							 GError		**error);

src/fu-plugin.c

@@ -43,6 +43,8 @@ typedef struct {
 	GModule			*module;
 	GUsbContext		*usb_ctx;
 	gboolean		 enabled;
+	guint			 order;
+	GPtrArray		*rules[FU_PLUGIN_RULE_LAST];
 	gchar			*name;
 	FuHwids			*hwids;
 	GPtrArray		*supported_guids;
@@ -1210,6 +1212,73 @@ fu_plugin_runner_get_results (FuPlugin *plugin, FuDevice *device, GError **error
 	return TRUE;
 }
 
+/**
+ * fu_plugin_get_order:
+ * @plugin: a #FuPlugin
+ *
+ * Gets the plugin order, where higher numbers are run after lower
+ * numbers.
+ *
+ * Returns: the integer value
+ **/
+guint
+fu_plugin_get_order (FuPlugin *plugin)
+{
+	FuPluginPrivate *priv = fu_plugin_get_instance_private (plugin);
+	return priv->order;
+}
+
+/**
+ * fu_plugin_set_order:
+ * @plugin: a #FuPlugin
+ * @order: a integer value
+ *
+ * Sets the plugin order, where higher numbers are run after lower
+ * numbers.
+ **/
+void
+fu_plugin_set_order (FuPlugin *plugin, guint order)
+{
+	FuPluginPrivate *priv = fu_plugin_get_instance_private (plugin);
+	priv->order = order;
+}
+
+/**
+ * fu_plugin_add_rule:
+ * @plugin: a #FuPlugin
+ * @rule: a #FuPluginRule, e.g. %FU_PLUGIN_RULE_CONFLICTS
+ * @name: a plugin name, e.g. "upower"
+ *
+ * If the plugin name is found, the rule will be used to sort the plugin list,
+ * for example the plugin specified by @name will be ordered after this plugin
+ * when %FU_PLUGIN_RULE_RUN_AFTER is used.
+ *
+ * NOTE: The depsolver is iterative and may not solve overly-complicated rules;
+ * If depsolving fails then fwupd will not start.
+ **/
+void
+fu_plugin_add_rule (FuPlugin *plugin, FuPluginRule rule, const gchar *name)
+{
+	FuPluginPrivate *priv = fu_plugin_get_instance_private (plugin);
+	g_ptr_array_add (priv->rules[rule], g_strdup (name));
+}
+
+/**
+ * fu_plugin_get_rules:
+ * @plugin: a #FuPlugin
+ * @rule: a #FuPluginRule, e.g. %FU_PLUGIN_RULE_CONFLICTS
+ *
+ * Gets the plugin IDs that should be run after this plugin.
+ *
+ * Returns: (element-type utf8) (transfer none): the list of plugin names, e.g. ['appstream']
+ **/
+GPtrArray *
+fu_plugin_get_rules (FuPlugin *plugin, FuPluginRule rule)
+{
+	FuPluginPrivate *priv = fu_plugin_get_instance_private (plugin);
+	return priv->rules[rule];
+}
+
 static void
 fu_plugin_class_init (FuPluginClass *klass)
 {
@@ -1267,6 +1336,8 @@ fu_plugin_init (FuPlugin *plugin)
 	priv->devices = g_hash_table_new_full (g_str_hash, g_str_equal,
 					       g_free, (GDestroyNotify) g_object_unref);
 	priv->devices_delay = g_hash_table_new (g_direct_hash, g_direct_equal);
+	for (guint i = 0; i < FU_PLUGIN_RULE_LAST; i++)
+		priv->rules[i] = g_ptr_array_new_with_free_func (g_free);
 }
 
 static void
@@ -1285,6 +1356,9 @@ fu_plugin_finalize (GObject *object)
 		}
 	}
 
+	for (guint i = 0; i < FU_PLUGIN_RULE_LAST; i++)
+		g_ptr_array_unref (priv->rules[i]);
+
 	if (priv->usb_ctx != NULL)
 		g_object_unref (priv->usb_ctx);
 	if (priv->hwids != NULL)

src/fu-plugin.h

@@ -63,6 +63,22 @@ typedef enum {
 	FU_PLUGIN_VERIFY_FLAG_LAST
 } FuPluginVerifyFlags;
 
+/**
+ * FuPluginRule:
+ * @FU_PLUGIN_RULE_CONFLICTS:		The plugin conflicts with another
+ * @FU_PLUGIN_RULE_RUN_AFTER:		Order the plugin after another
+ * @FU_PLUGIN_RULE_RUN_BEFORE:		Order the plugin before another
+ *
+ * The rules used for ordering plugins.
+ * Plugins are expected to add rules in fu_plugin_initialize().
+ **/
+typedef enum {
+	FU_PLUGIN_RULE_CONFLICTS,
+	FU_PLUGIN_RULE_RUN_AFTER,
+	FU_PLUGIN_RULE_RUN_BEFORE,
+	FU_PLUGIN_RULE_LAST
+} FuPluginRule;
+
 typedef struct	FuPluginData	FuPluginData;
 
 /* for plugins to use */
@@ -108,6 +124,9 @@ const gchar	*fu_plugin_get_smbios_string		(FuPlugin	*plugin,
 							 guint8		 offset);
 GBytes		*fu_plugin_get_smbios_data		(FuPlugin	*plugin,
 							 guint8		 structure_type);
+void		 fu_plugin_add_rule			(FuPlugin	*plugin,
+							 FuPluginRule	 rule,
+							 const gchar	*name);
 
 G_END_DECLS