------------------------------------------------------------------------ --- This is the main program of the CPNS demon. --- --- @author Michael Hanus --- @version November 2018 ------------------------------------------------------------------------ module Network.CPNSD where import Directory ( doesFileExist ) import IO ( hFlush, hPutStrLn, stderr ) import System ( getArgs, getPID, system ) import Time ( calendarTimeToString, getLocalTime ) import Network.CPNS import Network.CPNS.Config --- Main function for CPNS demon. Check arguments and execute command. main :: IO () main = do args <- getArgs case args of ["serve"] -> cpnsStart ["start"] -> startServerIfNecessary ["stop"] -> stopServer ["status"] -> cpnsStatus ["log"] -> do logfile <- getLogFile readFile logfile >>= putStr _ -> putErrLn $ "ERROR: Illegal arguments: " ++ unwords args ++ "\n" ++ "Allowed arguments: start | stop | serve | status | log" --- Start the Curry Port Name Server demon, if it is not already --- started on this machine: startServerIfNecessary :: IO () startServerIfNecessary = do alive <- cpnsAlive "localhost" unless alive $ do putErrLn "CPNS demon seems to be aborted. I try to restart it..." startServer startServer :: IO () startServer = do lockfile <- getStartupLockFile lfc <- system $ "lockfile-create --lock-name " ++ lockfile if lfc == 0 then do putErrLn "Starting demon for Curry Port Name Server..." logfile <- getLogFile exlogfile <- doesFileExist logfile unless exlogfile $ do -- create log file with correct access rights: system $ "touch " ++ logfile -- make log file accessible for everybody: system $ "chmod -f 666 " ++ logfile done putErrLn $ "Log information in file '" ++ logfile ++ "'" ctime <- getLocalTime appendFile logfile $ "CPNS demon started at " ++ calendarTimeToString ctime ++ "\n" -- start CPNSD in server mode: cpnsbin <- getCPNSD system $ "nohup \"" ++ cpnsbin ++ "\" serve >> " ++ logfile ++ " 2>&1 &" lockFileCreateAndRemove lockfile putErrLn "CPNS demon started." else do putErrLn "CPNS demon seems already started by another process" putErrLn $ "If this is not the case, delete file '" ++ lockfile ++ "'" lockFileCreateAndRemove lockfile where -- wait for lockfile deletion by CPNS demon startup: lockFileCreateAndRemove lockfile = do system $ "lockfile-create --lock-name " ++ lockfile system $ "lockfile-remove --lock-name " ++ lockfile done --- Terminate the Curry Port Name Server demon, if it is not already terminated. stopServer :: IO () stopServer = do lockfile <- getStartupLockFile system $ "/bin/rm -f " ++ lockfile -- just to be sure -- test whether the server process is still alive: alive <- cpnsAlive "localhost" if alive then cpnsStop else putErrLn "CPNS demon does not seem to be alive" putErrLn :: String -> IO () putErrLn s = hPutStrLn stderr s >> hFlush stderr