[PATCH BlueZ v4 5/8] bluetoothd: factor out external plugin support

[Emil Velikov <emil.l.velikov@gmail.com>]

From: Emil Velikov <emil.velikov@collabora.com>

As a whole all plugins should be built-in, otherwise they would be using
internal, undocumented, unversioned, unstable API.

Flesh out the external plugin support and simplify the normal path.
Guard the external plugin support behind a runtime check, which will be
dead-code eliminated in the default case.
---
 Makefile.am  |  4 ---
 src/btd.h    |  2 +-
 src/plugin.c | 92 +++++++++++++++++++++++++++++++++++++-----------------------
 src/plugin.h |  4 +++
 4 files changed, 62 insertions(+), 40 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index 9e35d7fd9..2d5650ced 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -51,11 +51,7 @@ EXTRA_DIST += src/org.bluez.service
 
 plugindir = $(libdir)/bluetooth/plugins
 
-if MAINTAINER_MODE
-build_plugindir = $(abs_top_srcdir)/plugins/.libs
-else
 build_plugindir = $(plugindir)
-endif
 
 if MANPAGES
 man_MANS =
diff --git a/src/btd.h b/src/btd.h
index b7e7ebd61..7166e2168 100644
--- a/src/btd.h
+++ b/src/btd.h
@@ -155,7 +155,7 @@ struct btd_opts {
 
 extern struct btd_opts btd_opts;
 
-gboolean plugin_init(const char *enable, const char *disable);
+void plugin_init(const char *enable, const char *disable);
 void plugin_cleanup(void);
 
 void rfkill_init(void);
diff --git a/src/plugin.c b/src/plugin.c
index 2a29a888e..b6a84299a 100644
--- a/src/plugin.c
+++ b/src/plugin.c
@@ -26,6 +26,8 @@
 #include "src/log.h"
 #include "src/btd.h"
 
+#define IS_ENABLED(x) (x)
+
 static GSList *plugins = NULL;
 
 struct bluetooth_plugin {
@@ -42,7 +44,7 @@ static int compare_priority(gconstpointer a, gconstpointer b)
 	return plugin2->desc->priority - plugin1->desc->priority;
 }
 
-static gboolean add_plugin(void *handle,
+static gboolean add_external_plugin(void *handle,
 				const struct bluetooth_plugin_desc *desc)
 {
 	struct bluetooth_plugin *plugin;
@@ -72,6 +74,21 @@ static gboolean add_plugin(void *handle,
 	return TRUE;
 }
 
+static void add_plugin(const struct bluetooth_plugin_desc *desc)
+{
+	struct bluetooth_plugin *plugin;
+
+	DBG("Loading %s plugin", desc->name);
+
+	plugin = g_try_new0(struct bluetooth_plugin, 1);
+	if (plugin == NULL)
+		return;
+
+	plugin->desc = desc;
+
+	plugins = g_slist_insert_sorted(plugins, plugin, compare_priority);
+}
+
 static gboolean enable_plugin(const char *name, char **cli_enable,
 							char **cli_disable)
 {
@@ -98,48 +115,23 @@ static gboolean enable_plugin(const char *name, char **cli_enable,
 	return TRUE;
 }
 
-#include "src/builtin.h"
 
-gboolean plugin_init(const char *enable, const char *disable)
+static void external_plugin_init(char **cli_disabled, char **cli_enabled)
 {
-	GSList *list;
 	GDir *dir;
 	const char *file;
-	char **cli_disabled, **cli_enabled;
-	unsigned int i;
-
-	/* Make a call to BtIO API so its symbols got resolved before the
-	 * plugins are loaded. */
-	bt_io_error_quark();
-
-	if (enable)
-		cli_enabled = g_strsplit_set(enable, ", ", -1);
-	else
-		cli_enabled = NULL;
-
-	if (disable)
-		cli_disabled = g_strsplit_set(disable, ", ", -1);
-	else
-		cli_disabled = NULL;
-
-	DBG("Loading builtin plugins");
-
-	for (i = 0; __bluetooth_builtin[i]; i++) {
-		if (!enable_plugin(__bluetooth_builtin[i]->name, cli_enabled,
-								cli_disabled))
-			continue;
 
-		add_plugin(NULL,  __bluetooth_builtin[i]);
-	}
+	info("Using external plugins is not officially supported.\n");
+	info("Consider upstreaming your plugins into the BlueZ project.");
 
 	if (strlen(PLUGINDIR) == 0)
-		goto start;
+		return;
 
 	DBG("Loading plugins %s", PLUGINDIR);
 
 	dir = g_dir_open(PLUGINDIR, 0, NULL);
 	if (!dir)
-		goto start;
+		return;
 
 	while ((file = g_dir_read_name(dir)) != NULL) {
 		const struct bluetooth_plugin_desc *desc;
@@ -174,13 +166,45 @@ gboolean plugin_init(const char *enable, const char *disable)
 			continue;
 		}
 
-		if (add_plugin(handle, desc) == FALSE)
+		if (add_external_plugin(handle, desc) == FALSE)
 			dlclose(handle);
 	}
 
 	g_dir_close(dir);
+}
+
+#include "src/builtin.h"
+
+void plugin_init(const char *enable, const char *disable)
+{
+	GSList *list;
+	char **cli_disabled = NULL;
+	char **cli_enabled = NULL;
+	unsigned int i;
+
+	/* Make a call to BtIO API so its symbols got resolved before the
+	 * plugins are loaded. */
+	bt_io_error_quark();
+
+	if (enable)
+		cli_enabled = g_strsplit_set(enable, ", ", -1);
+
+	if (disable)
+		cli_disabled = g_strsplit_set(disable, ", ", -1);
+
+	DBG("Loading builtin plugins");
+
+	for (i = 0; __bluetooth_builtin[i]; i++) {
+		if (!enable_plugin(__bluetooth_builtin[i]->name, cli_enabled,
+								cli_disabled))
+			continue;
+
+		add_plugin(__bluetooth_builtin[i]);
+	}
+
+	if IS_ENABLED(EXTERNAL_PLUGINS)
+		external_plugin_init(cli_enabled, cli_disabled);
 
-start:
 	for (list = plugins; list; list = list->next) {
 		struct bluetooth_plugin *plugin = list->data;
 		int err;
@@ -201,8 +225,6 @@ start:
 
 	g_strfreev(cli_enabled);
 	g_strfreev(cli_disabled);
-
-	return TRUE;
 }
 
 void plugin_cleanup(void)
diff --git a/src/plugin.h b/src/plugin.h
index 8d0903f2d..b484ed378 100644
--- a/src/plugin.h
+++ b/src/plugin.h
@@ -28,6 +28,7 @@ struct bluetooth_plugin_desc {
 			#name, version, priority, init, exit \
 		};
 #else
+#if EXTERNAL_PLUGINS
 #define BLUETOOTH_PLUGIN_DEFINE(name, version, priority, init, exit) \
 		extern struct btd_debug_desc __start___debug[] \
 				__attribute__ ((weak, visibility("hidden"))); \
@@ -40,4 +41,7 @@ struct bluetooth_plugin_desc {
 			#name, version, priority, init, exit, \
 			__start___debug, __stop___debug \
 		};
+#else
+#error "Requested non built-in plugin, while external plugins is disabled"
+#endif
 #endif

-- 
2.43.0