displaymanager: Disable basic setup by default.

Add a "basicSetup" boolean setting and default to leaving this kind of
setup operations to the distribution packages (i.e., to
"basicSetup: false").

src/modules/displaymanager/displaymanager.conf

@@ -16,3 +16,7 @@ displaymanagers:
 #    executable: "startkde"
 #    desktop_file: "plasma"
 
+#If true, try to ensure that the user, group, /var directory etc. for the
+#display manager are set up correctly. This is normally done by the distribution
+#packages, and best left to them. Therefore, it is disabled by default.
+basicSetup: false

src/modules/displaymanager/main.py

@@ -217,6 +217,11 @@ def run():
     else:
         default_desktop_environment = find_desktop_environment(root_mount_point)
 
+    if "basicSetup" in libcalamares.job.configuration:
+        enable_basic_setup = libcalamares.job.configuration["basicSetup"]
+    else:
+        enable_basic_setup = False
+
     # Setup slim
     if "slim" in displaymanagers:
         if not os.path.exists("%s/usr/bin/slim" % root_mount_point):
@@ -232,6 +237,7 @@ def run():
     # setup lightdm
     if "lightdm" in displaymanagers:
         if os.path.exists("%s/usr/bin/lightdm" % root_mount_point):
+            if enable_basic_setup:
                 libcalamares.utils.chroot_call(['mkdir', '-p', '/run/lightdm'])
                 libcalamares.utils.chroot_call(['getent', 'group', 'lightdm'])
                 libcalamares.utils.chroot_call(
@@ -243,11 +249,11 @@ def run():
                 libcalamares.utils.chroot_call(['passwd', '-l', 'lightdm'])
                 libcalamares.utils.chroot_call(
                     ['chown', '-R', 'lightdm:lightdm', '/run/lightdm'])
+                libcalamares.utils.chroot_call(
+                    ['chmod', '+r' '/etc/lightdm/lightdm.conf'])
             if default_desktop_environment != None:
                 os.system(
                     "sed -i -e 's/^.*user-session=.*/user-session=%s/' %s/etc/lightdm/lightdm.conf" % (default_desktop_environment.desktop_file, root_mount_point))
-            libcalamares.utils.chroot_call(
-                ['chmod', '+r' '/etc/lightdm/lightdm.conf'])
         else:
             libcalamares.utils.debug("lightdm selected but not installed")
             displaymanagers.remove("lightdm")
@@ -255,6 +261,7 @@ def run():
     # Setup gdm
     if "gdm" in displaymanagers:
         if os.path.exists("%s/usr/bin/gdm" % root_mount_point):
+            if enable_basic_setup:
                 libcalamares.utils.chroot_call(['getent', 'group', 'gdm'])
                 libcalamares.utils.chroot_call(['groupadd', '-g', '120', 'gdm'])
                 libcalamares.utils.chroot_call(['getent', 'passwd', 'gdm'])
@@ -271,6 +278,7 @@ def run():
     # Setup mdm
     if "mdm" in displaymanagers:
         if os.path.exists("%s/usr/bin/mdm" % root_mount_point):
+            if enable_basic_setup:
                 libcalamares.utils.chroot_call(['getent', 'group', 'mdm'])
                 libcalamares.utils.chroot_call(['groupadd', '-g', '128', 'mdm'])
                 libcalamares.utils.chroot_call(['getent', 'passwd', 'mdm'])
@@ -291,16 +299,17 @@ def run():
     # Setup lxdm
     if "lxdm" in displaymanagers:
         if os.path.exists("%s/usr/bin/lxdm" % root_mount_point):
+            if enable_basic_setup:
                 libcalamares.utils.chroot_call(['groupadd', '--system', 'lxdm'])
-            if default_desktop_environment != None:
-                os.system(
-                    "sed -i -e 's|^.*session=.*|session=%s|' %s/etc/lxdm/lxdm.conf" % (default_desktop_environment.executable, root_mount_point))
                 libcalamares.utils.chroot_call(
                     ['chgrp', '-R', 'lxdm', '/var/lib/lxdm'])
                 libcalamares.utils.chroot_call(
                     ['chgrp', 'lxdm', '/etc/lxdm/lxdm.conf'])
                 libcalamares.utils.chroot_call(
                     ['chmod', '+r', '/etc/lxdm/lxdm.conf'])
+            if default_desktop_environment != None:
+                os.system(
+                    "sed -i -e 's|^.*session=.*|session=%s|' %s/etc/lxdm/lxdm.conf" % (default_desktop_environment.executable, root_mount_point))
         else:
             libcalamares.utils.debug("lxdm selected but not installed")
             displaymanagers.remove("lxdm")
@@ -308,6 +317,7 @@ def run():
     # Setup kdm
     if "kdm" in displaymanagers:
         if os.path.exists("%s/usr/bin/kdm" % root_mount_point):
+            if enable_basic_setup:
                 libcalamares.utils.chroot_call(['getent', 'group', 'kdm'])
                 libcalamares.utils.chroot_call(['groupadd', '-g', '135', 'kdm'])
                 libcalamares.utils.chroot_call(['getent', 'passwd', 'kdm'])