adding fcron daemon.

I have only tested it with upstart 0.5, maybe you have to fix small things in the job description

svn path=/nixos/trunk/; revision=13369

system/options.nix

@@ -3035,6 +3035,7 @@ root        ALL=(ALL) SETENV: ALL
 
     # services
     (import ../upstart-jobs/cron.nix)
+    (import ../upstart-jobs/fcron.nix)
     (import ../upstart-jobs/cron/locate.nix)
   ];
 }

upstart-jobs/fcron.nix

@@ -0,0 +1,137 @@
+{pkgs, config}:
+
+###### interface
+let
+  inherit (pkgs.lib) mkOption concatStringsSep;
+  inherit (pkgs) writeText;
+
+  options = {
+    services = {
+      fcron = {
+        enable = mkOption {
+          default = false;
+          description = ''Whether to enable the `fcron' daemon.
+            From its docs: "fcron does both the job of Vixie Cron and anacron, but does even more and better".
+            It can trigger actions even if the event has passed due to shutdown for example.
+            TODO: add supoprt for fcron.allow and fcron.deny
+            Of course on cron daemon is enough.. So if fcron works fine there should be a system option systemCron="fcron or cron"
+
+            There are (or have been) some security issues.
+            I haven't yet checked wether they have been resolved.
+            For now you should trust the users registering crontab files.
+            I think gentoo has them listed.
+          '';
+        };
+        allow = mkOption {
+          default = [];
+          description = ''
+            Users allowed to use fcrontab and fcrondyn (one name per line, special name "all" acts for everyone)
+            nix adds username "root" for you.
+          '';
+        };
+        deny = mkOption {
+          default = [];
+          description = " same as allow but deny ";
+        };
+        maxSerialJobs = mkOption {
+          default = 1;
+          description = "maximum number of serial jobs which can run simultaneously (-m)";
+        };
+        queuelen = mkOption {
+          default = "";
+          description = "number of jobs the serial queue and the lavg queue can contain - empty to net set this number (-q)";
+        };
+        systab = mkOption {
+          default = "";
+          description = ''
+            The "system" crontab contents..
+          '';
+        };
+      };
+    };
+  };
+in
+
+###### implementation
+let
+  # Put all the system cronjobs together.
+  # TODO allow using fcron only..
+  #systemCronJobs =
+  #  config.services.cron.systemCronJobs;
+  cfg = config.services.fcron;
+  queuelen = if cfg.queuelen == "" then "" else "-q ${toString cfg.queuelen}";
+
+  # shell is set to /sh in config..
+  # ${pkgs.lib.concatStrings (map (job: job + "\n") systemCronJobs)}
+  systemCronJobsFile = pkgs.writeText "fcron-systab" ''
+    SHELL=${pkgs.bash}/bin/sh
+    PATH=${pkgs.coreutils}/bin:${pkgs.findutils}/bin:${pkgs.gnused}/bin
+  '';
+
+  allowdeny = target: users : {
+    source = writeText "fcron.${target}" (concatStringsSep "\n" users);
+    target = "fcron.${target}";
+    mode = "600"; # fcron has some security issues.. So I guess this is most safe
+  };
+
+in
+
+{
+  require = [
+    # (import ../upstart-jobs/default.nix) # config.services.extraJobs
+    # (import ?) # config.time.timeZone
+    # (import ?) # config.environment.etc
+    # (import ?) # config.environment.extraPackages
+    # (import ?) # config.environment.cleanStart
+    options
+  ];
+
+  environment = {
+    etc = [
+      (allowdeny "allow" (["root"] ++ cfg.allow))
+      (allowdeny "deny" cfg.deny)
+      # see man 5 fcron.conf
+      { source = writeText "fcon.conf" ''
+          fcrontabs	=	/var/spool/fcron
+          pidfile	=	/var/run/fcron.pid
+          fifofile	=	/var/run/fcron.fifo
+          fcronallow	=	/etc/fcron.allow
+          fcrondeny	=	/etc/fcron.deny
+          shell		=	/bin/sh
+          sendmail	=	/var/setuid-wrappers/sendmail
+          editor	=	/var/run/current-system/sw/bin/vi
+       '';
+        target = "fcron.conf";
+        mode = "0600"; # max allowed is 644
+      }
+    ];
+
+    extraPackages =
+      pkgs.lib.optional
+        (!config.environment.cleanStart)
+        pkgs.fcron;
+  };
+
+  services = {
+    extraJobs = [{
+      name = "fcron";
+
+      job = ''
+        description "fcron daemon"
+
+        start on startup
+        stop on shutdown
+
+        env PATH=/var/run/current-system/sw/bin
+
+        start script
+            ${pkgs.coreutils}/bin/mkdir -m 0700 -p /var/spool/fcron
+            # load system crontab file
+            ${pkgs.fcron}/bin/fcrontab -u systab ${writeText "systab" cfg.systab}
+        end script
+
+        respawn ${pkgs.fcron}/sbin/fcron -f -m ${toString cfg.maxSerialJobs} ${queuelen}
+      '';
+    }];
+  };
+}