build: Rename have_libsystemd to have_logind

We really only need the logind API which can be provided either by
libsystemd or libelogind.

This also pulls out finding a logind provider from the native backend
only code because we make use of it in the generic backend code as well.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4223>

config.h.meson

@@ -51,8 +51,8 @@
 /* libwacom has get_num_rings() */
 #mesondefine HAVE_LIBWACOM_GET_NUM_RINGS
 
-/* Building with libsystemd */
+/* Building with logind */
-#mesondefine HAVE_LIBSYSTEMD
+#mesondefine HAVE_LOGIND
 
 /* Define if you want to enable the native (KMS) backend based on systemd */
 #mesondefine HAVE_NATIVE_BACKEND

meson.build

@@ -239,6 +239,19 @@ if have_wayland
   endif
 endif
 
+have_logind = get_option('logind')
+if have_logind
+  logind_dep = dependency('libsystemd', required: false)
+
+  if not logind_dep.found()
+    logind_dep = dependency('libelogind', required: false)
+  endif
+
+  if not logind_dep.found()
+    error('No logind provider dependency found: tried libsystemd and libelogind')
+  endif
+endif
+
 have_libgudev = get_option('udev')
 if have_libgudev
   libudev_dep = dependency('libudev', version: udev_req)
@@ -251,18 +264,13 @@ if have_libgudev
   endif
 endif
 
-have_libsystemd = get_option('systemd')
-libsystemd_dep = dependency('libsystemd', required: have_libsystemd)
-
 have_native_backend = get_option('native_backend')
 if have_native_backend
   libgbm_dep = dependency('gbm', version: gbm_req)
   libinput_dep = dependency('libinput', version: libinput_req)
 
-  if libsystemd_dep.found()
+  if not have_logind
-    logind_provider_dep = libsystemd_dep
+    error('The native backend requires logind to be enabled')
-  else
-    logind_provider_dep = dependency('libelogind')
   endif
 
   if not have_egl
@@ -557,7 +565,7 @@ cdata.set('HAVE_WAYLAND', have_wayland)
 cdata.set('HAVE_XWAYLAND', have_xwayland)
 cdata.set('HAVE_X11', have_x11)
 cdata.set('HAVE_X11_CLIENT', have_x11_client)
-cdata.set('HAVE_LIBSYSTEMD', have_libsystemd)
+cdata.set('HAVE_LOGIND', have_logind)
 cdata.set('HAVE_NATIVE_BACKEND', have_native_backend)
 cdata.set('HAVE_REMOTE_DESKTOP', have_remote_desktop)
 cdata.set('HAVE_GNOME_DESKTOP', have_gnome_desktop)

meson.options

@@ -51,10 +51,10 @@ option('x11',
   description: 'Enable X11 support'
 )
 
-option('systemd',
+option('logind',
   type: 'boolean',
   value: true,
-  description: 'Enable systemd support'
+  description: 'Enable logind support'
 )
 
 option('native_backend',

src/core/window.c

@@ -109,7 +109,7 @@
 #include "wayland/meta-window-xwayland.h"
 #endif
 
-#ifdef HAVE_LIBSYSTEMD
+#ifdef HAVE_LOGIND
 #include <systemd/sd-login.h>
 #endif
 
@@ -6813,7 +6813,7 @@ meta_window_get_pid (MetaWindow *window)
 GFile *
 meta_window_get_unit_cgroup (MetaWindow *window)
 {
-#ifdef HAVE_LIBSYSTEMD
+#ifdef HAVE_LOGIND
   g_autofree char *contents = NULL;
   g_autofree char *complete_path = NULL;
   g_autofree char *unit_name = NULL;

src/meson.build

@@ -135,9 +135,9 @@ if have_wayland
   ]
 endif
 
-if have_libsystemd
+if have_logind
   mutter_pkg_private_deps += [
-    libsystemd_dep,
+    logind_dep,
   ]
 endif
 
@@ -145,7 +145,6 @@ if have_native_backend
   mutter_pkg_private_deps += [
     libinput_dep,
     libgbm_dep,
-    logind_provider_dep,
     xkbcommon_dep,
   ]
 endif