pdist: Add option --set-pdist-status

Add option --set-pdist-status. This option make the client write a
status file /.pdist_status when everything completed successfully. It is
supposed to be used only during full dists from the distmaster.

The idea is that health check scripts can look at the status file  and
the embededed time tag to find out when a system was successfully updated
and generate an alarm if this is to long in the past.

pdist/pdist

@@ -187,7 +187,7 @@ $SIG{PIPE} = sub {clean_tmp();exit 1;};
 
 # options
 
-our ($debug,$quiet,$fileop_noop,$fileop_debug,$delete);
+our ($debug,$quiet,$fileop_noop,$fileop_debug,$delete,$set_pdist_status);
 our ($verbose,$timeout,@files,$ssh_tunnel,$post_command,$parallel,$prompt,$msg_prefix);
 our ($distfilename) = (DISTFILE);
 
@@ -829,6 +829,13 @@ sub prog_update
 				warn "$fn: $!\n";
 			}
 		}
+
+		if ( !$fileop_noop && $set_pdist_status) {
+			my $t=time;
+			open L,'>','/.pdist_status' or die "/.pdist_status: $!\n";
+			print L 'OK',$t,scalar(localtime($t));
+			close L;
+		}
 	}
 
 	if ($function==F_REQUEST) {
@@ -1014,6 +1021,8 @@ sub push_single
 		$fileop_debug and push @remote_opts,'--fileop_debug';
 		$debug and push @remote_opts,'--debug';
 		push @remote_opts,$delete ? '--delete' : '--nodelete';
+		$set_pdist_status and push @remote_opts,'--set-pdist-status';
+
 		$post_command and push @remote_opts,'--post-command='.quotemeta($post_command);
 
 		$parallel && $parallel>1 and push @remote_opts,'--msg-prefix',$client;
@@ -1186,6 +1195,7 @@ usage: $0 cmd [options]
 	--fileop_debug          # log all file operations
 	--[no]delete		# do or do not clean up additional files on client.
 				# default is delete unless --files is used
+	--set-pdist-status	# force creation of /.pdist_status on target
 
 	--verbose		# be more verbose
 	--fileop_noop		# DEPRECATED: now --noop
@@ -1222,6 +1232,7 @@ use constant OPTIONS => (
 
 	'fileop_debug'   => \$fileop_debug,
 	'delete!'        => \$delete,
+	'set-pdist-status' => \$set_pdist_status,
 
 	'verbose'	 => \$verbose,
 	'debug'		 => \$debug,