look for an init system and auto install based on what is found

contrib/openrc/meson.build

@@ -1,5 +1,3 @@
-openrc = get_option('openrc')
-
 openrc_config_data = configuration_data()
 openrc_config_data.set('SBINDIR', join_paths(get_option('prefix'), get_option('sbindir')))
 openrc_config_data.set('LIBEXECDIR', join_paths(get_option('prefix'), get_option('libexecdir'), meson.project_name()))
@@ -10,7 +8,9 @@ openrc_config_data_file = configure_file(
     configuration: openrc_config_data
 )
 
-if openrc
+openrc = find_program ('openrc', required: false)
+
+if openrc.found()
     install_data(
         openrc_config_data_file,
         install_dir: join_paths(get_option('sysconfdir'), 'init.d')

contrib/runit/meson.build

@@ -1,5 +1,3 @@
-runit = get_option('runit')
-
 runit_config_data = configuration_data()
 runit_config_data.set('LIBEXECDIR', join_paths(get_option('prefix'), get_option('libexecdir'), meson.project_name()))
 
@@ -9,7 +7,9 @@ runit_config_data_file = configure_file(
     configuration: runit_config_data
 )
 
-if runit
+runit = find_program ('runit', required: false)
+
+if runit.found()
     install_data(
         runit_config_data_file,
         install_dir: join_paths(get_option('sysconfdir'), 'runit', 'sv', 'tufmanager')

contrib/s6/meson.build

@@ -1,5 +1,3 @@
-s6 = get_option('s6')
-
 s6_config_data = configuration_data()
 s6_config_data.set('LIBEXECDIR', join_paths(get_option('prefix'), get_option('libexecdir'), meson.project_name()))
 
@@ -9,7 +7,9 @@ s6_config_data_file = configure_file(
     configuration: s6_config_data
 )
 
-if s6
+s6 = find_program ('s6-init', required: false)
+
+if s6.found()
     install_data(
         [s6_config_data_file, 'type', 'dependencies'],
         install_dir: join_paths(get_option('sysconfdir'), 's6', 'sv', 'tufmanager')

contrib/systemd/meson.build

@@ -1,5 +1,3 @@
-systemd = get_option('systemd')
-
 systemd_config_data = configuration_data()
 systemd_config_data.set('LIBEXECDIR', join_paths(get_option('prefix'), get_option('libexecdir'), meson.project_name()))
 
@@ -9,7 +7,10 @@ systemd_config_data_file = configure_file(
     configuration: systemd_config_data
 )
 
-if systemd
+systemd = find_program ('systemd', required: false)
+
+if systemd.found()
+    message ('systemd was found')
     install_data(
         systemd_config_data_file,
         install_dir: join_paths(get_option('prefix'), 'lib', 'systemd', 'system')

meson_options.txt

@@ -34,27 +34,3 @@ option(
     value: true,
     description: 'User is always authenticated, so no password is necessary'
 )
-option(
-    'openrc',
-    type : 'boolean',
-    value: false,
-    description: 'Install OpenRC script'
-)
-option(
-    'runit',
-    type : 'boolean',
-    value: false,
-    description: 'Install runit script'
-)
-option(
-    's6',
-    type : 'boolean',
-    value: false,
-    description: 'Install s6 scripts'
-)
-option(
-    'systemd',
-    type : 'boolean',
-    value: false,
-    description: 'Install systemd unit'
-)