[gnome-settings-daemon/wip/benzea/sysfs-backlight-switch] power: Bind building sysfs backlight helper to meson option

[Benjamin Berg <bberg src gnome org>]

commit fbe20d212ede5cf5c7ba43307ad36a3bd32dd57b
Author: Benjamin Berg <bberg redhat com>
Date:   Mon Oct 1 10:52:53 2018 +0200

    power: Bind building sysfs backlight helper to meson option
    
    This is require so that BSDs can explicitly disable building the
    backlight helper. BSDs also have udev/GUdev support to some extend,
    which is why we need the explicit option.
    
    See issue #94

 meson.build                   |  8 ++++++++
 meson_options.txt             |  2 ++
 plugins/power/gsd-backlight.c | 28 ++++++++++++++--------------
 plugins/power/meson.build     |  4 ++--
 4 files changed, 26 insertions(+), 16 deletions(-)
---
diff --git a/meson.build b/meson.build
index 47cf3722..6a2b8ab4 100644
--- a/meson.build
+++ b/meson.build
@@ -126,6 +126,14 @@ if enable_gudev
 endif
 config_h.set10('HAVE_GUDEV', enable_gudev)
 
+# Linux sysfs backlight support (default enabled)
+enable_sysfs_backlight = get_option('sysfs_backlight')
+if enable_sysfs_backlight and not enable_gudev
+  assert(enable_gudev, 'GUDev support is required for sysfs backlight support.')
+endif
+config_h.set10('HAVE_SYSFS_BACKLIGHT', enable_sysfs_backlight)
+
+# Timer FD checking
 has_timerfd_create = cc.has_function('timerfd_create')
 config_h.set10('HAVE_TIMERFD', has_timerfd_create)
 
diff --git a/meson_options.txt b/meson_options.txt
index 50bd1749..241f4e81 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -8,3 +8,5 @@ option('network_manager', type: 'boolean', value: true, description: 'build with
 option('rfkill', type: 'boolean', value: true, description: 'build with rfkill support (not optional on 
Linux platforms)')
 option('smartcard', type: 'boolean', value: true, description: 'build with smartcard support')
 option('wayland', type: 'boolean', value: true, description: 'build with Wayland support')
+
+option('sysfs_backlight', type: 'boolean', value: true, description: 'build with brightness control code via 
sysfs for Linux platforms')
diff --git a/plugins/power/gsd-backlight.c b/plugins/power/gsd-backlight.c
index 2159f429..02cf044d 100644
--- a/plugins/power/gsd-backlight.c
+++ b/plugins/power/gsd-backlight.c
@@ -25,9 +25,9 @@
 #include "gsd-power-constants.h"
 #include "gsd-power-manager.h"
 
-#ifdef HAVE_GUDEV
+#ifdef HAVE_SYSFS_BACKLIGHT
 #include <gudev/gudev.h>
-#endif /* HAVE_GUDEV */
+#endif /* HAVE_SYSFS_BACKLIGHT */
 
 struct _GsdBacklight
 {
@@ -39,7 +39,7 @@ struct _GsdBacklight
         gint brightness_target;
         gint brightness_step;
 
-#ifdef HAVE_GUDEV
+#ifdef HAVE_SYSFS_BACKLIGHT
         GUdevClient *udev;
         GUdevDevice *udev_device;
 
@@ -47,7 +47,7 @@ struct _GsdBacklight
         GQueue tasks;
 
         gint idle_update;
-#endif
+#endif /* HAVE_SYSFS_BACKLIGHT */
 
         GnomeRRScreen *rr_screen;
 };
@@ -70,7 +70,7 @@ G_DEFINE_TYPE_EXTENDED (GsdBacklight, gsd_backlight, G_TYPE_OBJECT, 0,
                         G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
                                                gsd_backlight_initable_iface_init);)
 
-#ifdef HAVE_GUDEV
+#ifdef HAVE_SYSFS_BACKLIGHT
 static GUdevDevice*
 gsd_backlight_udev_get_type (GList *devices, const gchar *type)
 {
@@ -395,7 +395,7 @@ gsd_backlight_process_taskqueue (GsdBacklight *backlight)
         /* And run it! */
         gsd_backlight_run_set_helper (backlight, to_run);
 }
-#endif /* HAVE_GUDEV */
+#endif /* HAVE_SYSFS_BACKLIGHT */
 
 static GnomeRROutput*
 gsd_backlight_rr_find_output (GsdBacklight *backlight, gboolean controllable)
@@ -464,7 +464,7 @@ gsd_backlight_set_brightness_val_async (GsdBacklight *backlight,
 
         task = g_task_new (backlight, cancellable, callback, user_data);
 
-#ifdef HAVE_GUDEV
+#ifdef HAVE_SYSFS_BACKLIGHT
         if (backlight->udev_device != NULL) {
                 BacklightHelperData *task_data;
 
@@ -478,7 +478,7 @@ gsd_backlight_set_brightness_val_async (GsdBacklight *backlight,
 
                 return;
         }
-#endif /* HAVE_GUDEV */
+#endif /* HAVE_SYSFS_BACKLIGHT */
 
         /* Fallback to setting via GNOME RR/X11 */
         output = gsd_backlight_rr_find_output (backlight, TRUE);
@@ -716,11 +716,11 @@ gsd_backlight_initable_init (GInitable       *initable,
                 return FALSE;
         }
 
-#ifdef HAVE_GUDEV
+#ifdef HAVE_SYSFS_BACKLIGHT
         /* Try finding a udev device. */
         if (gsd_backlight_udev_init (backlight))
                 goto found;
-#endif /* HAVE_GUDEV */
+#endif /* HAVE_SYSFS_BACKLIGHT */
 
         /* Try GNOME RR as a fallback. */
         output = gsd_backlight_rr_find_output (backlight, TRUE);
@@ -755,7 +755,7 @@ gsd_backlight_finalize (GObject *object)
 {
         GsdBacklight *backlight = GSD_BACKLIGHT (object);
 
-#ifdef HAVE_GUDEV
+#ifdef HAVE_SYSFS_BACKLIGHT
         g_assert (backlight->active_task == NULL);
         g_assert (g_queue_is_empty (&backlight->tasks));
         g_clear_object (&backlight->udev);
@@ -764,7 +764,7 @@ gsd_backlight_finalize (GObject *object)
                 g_source_remove (backlight->idle_update);
                 backlight->idle_update = 0;
         }
-#endif /* HAVE_GUDEV */
+#endif /* HAVE_SYSFS_BACKLIGHT */
 
         g_clear_object (&backlight->rr_screen);
 }
@@ -807,10 +807,10 @@ gsd_backlight_init (GsdBacklight *backlight)
         backlight->brightness_val = -1;
         backlight->brightness_step = 1;
 
-#ifdef HAVE_GUDEV
+#ifdef HAVE_SYSFS_BACKLIGHT
         backlight->active_task = NULL;
         g_queue_init (&backlight->tasks);
-#endif /* HAVE_GUDEV */
+#endif /* HAVE_SYSFS_BACKLIGHT */
 }
 
 GsdBacklight *
diff --git a/plugins/power/meson.build b/plugins/power/meson.build
index 0158a466..30e95ee3 100644
--- a/plugins/power/meson.build
+++ b/plugins/power/meson.build
@@ -18,7 +18,7 @@ deps = plugins_deps + [
   dependency('xext')
 ]
 
-if enable_gudev
+if enable_sysfs_backlight
   deps += gudev_dep
 endif
 
@@ -59,7 +59,7 @@ gsd_power_enums_update = executable(
   c_args: cflags
 )
 
-if enable_gudev
+if enable_sysfs_backlight
   policy = 'org.gnome.settings-daemon.plugins.power.policy'
 
   policy_in = configure_file(