* When using kdm, always use our xsession script, even when the

default session is selected.  This is because we always want to run
  our own initialisation (like starting ssh-agent).

* ssh-agent: don't start it is a child but have it re-exec the
  xsession script.  This ensures that ssh-agent quits when we log out.

* In the xsession script, don't redirect output to ~/.xsession-errors
  if the display manager is kdm, since kdm already does that.  In fact
  it uses ~/.xsession-errors<optional number> if there are concurrent
  X sessions.

* For consistency with other distros and the xdm manpage, exec the
  ~/.xsession script instead of sourcing it.  Do this for the "custom"
  session type provided by kdm.

svn path=/nixos/trunk/; revision=17087

modules/services/x11/display-managers/default.nix

@@ -21,34 +21,46 @@ let
     ''
       #! /bin/sh
 
-      exec > $HOME/.xsession-errors 2>&1
+      # Handle being called by kdm.
+      if test "''${1:0:1}" = /; then eval exec "$1"; fi
 
-      source /etc/profile
+      # The first argument of this script is the session type.
+      sessionType="$1"
+      if test "$sessionType" = default; then sessionType=""; fi
 
-      ### Load X defaults.
+      ${optionalString (!cfg.displayManager.job.logsXsession) ''
+        exec > ~/.xsession-errors 2>&1
+      ''}
+
+      ${optionalString cfg.startSSHAgent ''
+        if test -z "$SSH_AUTH_SOCK"; then
+            # Restart this script as a child of the SSH agent.  (It is
+            # also possible to start the agent as a child that prints
+            # the required environment variabled on stdout, but in
+            # that mode ssh-agent is not terminated when we log out.)
+            export SSH_ASKPASS=${pkgs.x11_ssh_askpass}/libexec/x11-ssh-askpass
+            exec ${pkgs.openssh}/bin/ssh-agent "$0" "$sessionType"
+        fi
+      ''}
+
+      # Load X defaults.
       if test -e ~/.Xdefaults; then
           ${xorg.xrdb}/bin/xrdb -merge ~/.Xdefaults
       fi
 
-      ${optionalString cfg.startSSHAgent ''
+      source /etc/profile
-        ### Start the SSH agent.
-        export SSH_ASKPASS=${pkgs.x11_ssh_askpass}/libexec/x11-ssh-askpass
-        eval $(${pkgs.openssh}/bin/ssh-agent)
-      ''}
 
-      ### Allow user to override system-wide configuration
+      # Allow the user to setup a custom session type.
-      if test -f ~/.xsession; then
+      if test "$sessionType" = custom; then
-          source ~/.xsession
+          test -x ~/.xsession && exec ~/.xsession
+          sessionType="" # fall-thru if there is no ~/.xsession
       fi
 
-      # The first argument of this script is the session type
+      # The session type is "<desktop-manager> + <window-manager>", so
-      sessionType="$1"
-
-      # The session type "<desktop-manager> + <window-manager>", so
       # extract those.
-      windowManager="''${arg##* + }"
+      windowManager="''${sessionType##* + }"
       : ''${windowManager:=${cfg.windowManager.default}}
-      desktopManager="''${arg% + *}"
+      desktopManager="''${sessionType% + *}"
       : ''${desktopManager:=${cfg.desktopManager.default}}
 
       # Start the window manager.
@@ -178,6 +190,15 @@ in
             description = "Additional environment variables needed by the display manager.";
           };
          
+          logsXsession = mkOption {
+            default = false;
+            description = ''
+              Whether the display manager redirects the
+              output of the session script to
+              <filename>~/.xsession-errors</filename>.
+            '';
+          };
+         
         };
         
       };

modules/services/x11/display-managers/kdm.nix

@@ -18,6 +18,7 @@ let
       [X-*-Core]
       Xrdb=${pkgs.xlibs.xrdb}/bin/xrdb
       SessionsDirs=${dmcfg.session.desktops}
+      Session=${dmcfg.session.script}
       FailsafeClient=${pkgs.xterm}/bin/xterm
 
       [X-:*-Core]
@@ -76,6 +77,7 @@ in
   
     services.xserver.displayManager.job =
       { execCmd = "${kdebase_workspace}/bin/kdm -config ${kdmrc}";
+        logsXsession = true;
       };
 
     security.pam.services = [ { name = "kde"; localLogin = true; ckHack = true; } ];