backends/native: Add udev abstraction layer

To be used to signal devices added, hotplugs and other udev events.
Currently the only event emitted is when a device is added.

https://gitlab.gnome.org/GNOME/mutter/issues/548
https://gitlab.gnome.org/GNOME/mutter/merge_requests/525

src/backends/native/meta-backend-native.c

@@ -64,6 +64,7 @@ struct _MetaBackendNative
   MetaBackend parent;
 
   MetaLauncher *launcher;
+  MetaUdev *udev;
   MetaBarrierManagerNative *barrier_manager;
 };
 
@@ -81,6 +82,7 @@ meta_backend_native_finalize (GObject *object)
 {
   MetaBackendNative *native = META_BACKEND_NATIVE (object);
 
+  g_clear_object (&native->udev);
   meta_launcher_free (native->launcher);
 
   G_OBJECT_CLASS (meta_backend_native_parent_class)->finalize (object);
@@ -516,6 +518,8 @@ meta_backend_native_initable_init (GInitable     *initable,
                                    GCancellable  *cancellable,
                                    GError       **error)
 {
+  MetaBackendNative *native = META_BACKEND_NATIVE (initable);
+
   if (!meta_is_stage_views_enabled ())
     {
       g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
@@ -523,6 +527,8 @@ meta_backend_native_initable_init (GInitable     *initable,
       return FALSE;
     }
 
+  native->udev = meta_udev_new ();
+
   return initable_parent_iface->init (initable, cancellable, error);
 }
 
@@ -585,6 +591,12 @@ meta_backend_native_get_launcher (MetaBackendNative *native)
   return native->launcher;
 }
 
+MetaUdev *
+meta_backend_native_get_udev (MetaBackendNative *native)
+{
+  return native->udev;
+}
+
 gboolean
 meta_activate_vt (int vt, GError **error)
 {

src/backends/native/meta-backend-native.h

@@ -28,6 +28,7 @@
 #include "backends/meta-backend-private.h"
 #include "backends/native/meta-clutter-backend-native.h"
 #include "backends/native/meta-launcher.h"
+#include "backends/native/meta-udev.h"
 
 #define META_TYPE_BACKEND_NATIVE (meta_backend_native_get_type ())
 G_DECLARE_FINAL_TYPE (MetaBackendNative, meta_backend_native,
@@ -41,4 +42,6 @@ void meta_backend_native_resume (MetaBackendNative *backend_native);
 
 MetaLauncher * meta_backend_native_get_launcher (MetaBackendNative *native);
 
+MetaUdev * meta_backend_native_get_udev (MetaBackendNative *native);
+
 #endif /* META_BACKEND_NATIVE_H */

src/backends/native/meta-udev.c

@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2018 Red Hat
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ */
+
+#include "config.h"
+
+#include "backends/native/meta-udev.h"
+
+enum
+{
+  DEVICE_ADDED,
+
+  N_SIGNALS
+};
+
+static guint signals[N_SIGNALS];
+
+struct _MetaUdev
+{
+  GObject parent;
+
+  GUdevClient *gudev_client;
+
+  guint uevent_handler_id;
+};
+
+G_DEFINE_TYPE (MetaUdev, meta_udev, G_TYPE_OBJECT)
+
+static void
+on_uevent (GUdevClient *client,
+           const char  *action,
+           GUdevDevice *device,
+           gpointer     user_data)
+{
+  MetaUdev *udev = META_UDEV (user_data);
+
+  if (!g_udev_device_get_device_file (device))
+    return;
+
+  if (g_str_equal (action, "add"))
+    g_signal_emit (udev, signals[DEVICE_ADDED], 0, device);
+}
+
+GUdevClient *
+meta_udev_get_gudev_client (MetaUdev *udev)
+{
+  return udev->gudev_client;
+}
+
+MetaUdev *
+meta_udev_new (void)
+{
+  return g_object_new (META_TYPE_UDEV, NULL);
+}
+
+static void
+meta_udev_finalize (GObject *object)
+{
+  MetaUdev *udev = META_UDEV (object);
+
+  g_signal_handler_disconnect (udev->gudev_client, udev->uevent_handler_id);
+  g_clear_object (&udev->gudev_client);
+
+  G_OBJECT_CLASS (meta_udev_parent_class)->finalize (object);
+}
+
+static void
+meta_udev_init (MetaUdev *udev)
+{
+  const char *subsystems[] = { "drm", NULL };
+
+  udev->gudev_client = g_udev_client_new (subsystems);
+  udev->uevent_handler_id = g_signal_connect (udev->gudev_client,
+                                              "uevent",
+                                              G_CALLBACK (on_uevent), udev);
+}
+
+static void
+meta_udev_class_init (MetaUdevClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = meta_udev_finalize;
+
+  signals[DEVICE_ADDED] =
+    g_signal_new ("device-added",
+                  G_TYPE_FROM_CLASS (object_class),
+                  G_SIGNAL_RUN_LAST,
+                  0, NULL, NULL,
+                  g_cclosure_marshal_VOID__VOID,
+                  G_TYPE_NONE, 1,
+                  G_UDEV_TYPE_DEVICE);
+}

src/backends/native/meta-udev.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2018 Red Hat
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ */
+
+#ifndef META_UDEV_H
+#define META_UDEV_H
+
+#include <gudev/gudev.h>
+
+#define META_TYPE_UDEV (meta_udev_get_type ())
+G_DECLARE_FINAL_TYPE (MetaUdev, meta_udev, META, UDEV, GObject)
+
+GUdevClient * meta_udev_get_gudev_client (MetaUdev *udev);
+
+MetaUdev * meta_udev_new (void);
+
+#endif /* META_UDEV_H */

src/meson.build

@@ -599,6 +599,8 @@ if have_native_backend
     'backends/native/meta-renderer-native.h',
     'backends/native/meta-stage-native.c',
     'backends/native/meta-stage-native.h',
+    'backends/native/meta-udev.c',
+    'backends/native/meta-udev.h',
   ]
 endif