services: Add screen-locker service.

* gnu/system/linux.scm (base-pam-services): Remove "xlock" and
  "xscreensaver".
* gnu/services/xorg.scm (<screen-locker>): New record type.
  (screen-locker-pam-services, screen-locker-setuid-programs,
  screen-locker-service): New procedures.
  (screen-locker-service-type): New variable.
* gnu/services/desktop.scm (%desktop-services): Use them.
* doc/guix.texi (X Window): Document 'screen-locker-service'.
  (Desktop Services): Mention it.

1 files changed, 15 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index b5c08f5d9c..844f9fa75d 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -6496,6 +6496,19 @@ Last, @var{extra-config} is a list of strings or objects appended to the
 verbatim to the configuration file.
 @end deffn
 
+@deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
+Add @var{package}, a package for a screen-locker or screen-saver whose
+command is @var{program}, to the set of setuid programs and add a PAM entry
+for it.  For example:
+
+@lisp
+(screen-locker-service xlockmore "xlock")
+@end lisp
+
+makes the good ol' XlockMore usable.
+@end deffn
+
+
 @node Desktop Services
 @subsubsection Desktop Services
 
@@ -6513,7 +6526,8 @@ This is a list of services that builds upon @var{%base-services} and
 adds or adjust services for a typical ``desktop'' setup.
 
 In particular, it adds a graphical login manager (@pxref{X Window,
-@code{slim-service}}), a network management tool (@pxref{Networking
+@code{slim-service}}), screen lockers,
+a network management tool (@pxref{Networking
 Services, @code{wicd-service}}), energy and color management services,
 the @code{elogind} login and seat manager, the Polkit privilege service,
 the GeoClue location service, an NTP client (@pxref{Networking