hsyslog-1.5: System/Posix/Syslog.hsc
{-# LANGUAGE ForeignFunctionInterface #-}
{- |
Module : System.Posix.Syslog
Copyright : (c) 2008 Peter Simons
License : BSD3
Maintainer : simons@cryp.to
Stability : provisional
Portability : Posix
FFI bindings to Unix's @syslog(3)@. Process this file
with @hsc2hs@ to obtain a Haskell module.
-}
module System.Posix.Syslog where
import Control.Exception ( bracket_ )
import Foreign.C
#include <syslog.h>
#ifndef LOG_AUTHPRIV
#define LOG_AUTHPRIV LOG_AUTH
#endif
#ifndef LOG_FTP
#define LOG_FTP LOG_DAEMON
#endif
#ifndef LOG_PERROR
#define LOG_PERROR 0
#endif
-- * Marshaled Data Types
-- |Log messages are prioritized.
data Priority
= Emergency -- ^ system is unusable
| Alert -- ^ action must be taken immediately
| Critical -- ^ critical conditions
| Error -- ^ error conditions
| Warning -- ^ warning conditions
| Notice -- ^ normal but significant condition
| Info -- ^ informational
| Debug -- ^ debug-level messages
deriving (Eq, Bounded, Show)
instance Enum Priority where
toEnum #{const LOG_EMERG} = Emergency
toEnum #{const LOG_ALERT} = Alert
toEnum #{const LOG_CRIT} = Critical
toEnum #{const LOG_ERR} = Error
toEnum #{const LOG_WARNING} = Warning
toEnum #{const LOG_NOTICE} = Notice
toEnum #{const LOG_INFO} = Info
toEnum #{const LOG_DEBUG} = Debug
toEnum i = error (showString "Syslog.Priority cannot be mapped from value " (show i))
fromEnum Emergency = #{const LOG_EMERG}
fromEnum Alert = #{const LOG_ALERT}
fromEnum Critical = #{const LOG_CRIT}
fromEnum Error = #{const LOG_ERR}
fromEnum Warning = #{const LOG_WARNING}
fromEnum Notice = #{const LOG_NOTICE}
fromEnum Info = #{const LOG_INFO}
fromEnum Debug = #{const LOG_DEBUG}
-- |Syslog distinguishes various system facilities. Most
-- applications should log in 'USER'.
data Facility
= KERN -- ^ kernel messages
| USER -- ^ user-level messages (default unless set otherwise)
| MAIL -- ^ mail system
| DAEMON -- ^ system daemons
| AUTH -- ^ security\/authorization messages
| SYSLOG -- ^ messages generated internally by syslogd
| LPR -- ^ line printer subsystem
| NEWS -- ^ network news subsystem
| UUCP -- ^ UUCP subsystem
| CRON -- ^ clock daemon
| AUTHPRIV -- ^ security\/authorization messages (effectively equals 'AUTH' on some systems)
| FTP -- ^ ftp daemon (effectively equals 'DAEMON' on some systems)
| LOCAL0 -- ^ reserved for local use
| LOCAL1 -- ^ reserved for local use
| LOCAL2 -- ^ reserved for local use
| LOCAL3 -- ^ reserved for local use
| LOCAL4 -- ^ reserved for local use
| LOCAL5 -- ^ reserved for local use
| LOCAL6 -- ^ reserved for local use
| LOCAL7 -- ^ reserved for local use
deriving (Eq, Bounded, Show)
instance Enum Facility where
toEnum #{const LOG_KERN} = KERN
toEnum #{const LOG_USER} = USER
toEnum #{const LOG_MAIL} = MAIL
toEnum #{const LOG_DAEMON} = DAEMON
toEnum #{const LOG_AUTH} = AUTH
toEnum #{const LOG_SYSLOG} = SYSLOG
toEnum #{const LOG_LPR} = LPR
toEnum #{const LOG_NEWS} = NEWS
toEnum #{const LOG_UUCP} = UUCP
toEnum #{const LOG_CRON} = CRON
toEnum #{const LOG_AUTHPRIV} = AUTHPRIV
toEnum #{const LOG_FTP} = FTP
toEnum #{const LOG_LOCAL0} = LOCAL0
toEnum #{const LOG_LOCAL1} = LOCAL1
toEnum #{const LOG_LOCAL2} = LOCAL2
toEnum #{const LOG_LOCAL3} = LOCAL3
toEnum #{const LOG_LOCAL4} = LOCAL4
toEnum #{const LOG_LOCAL5} = LOCAL5
toEnum #{const LOG_LOCAL6} = LOCAL6
toEnum #{const LOG_LOCAL7} = LOCAL7
toEnum i = error ("Syslog.Facility cannot be mapped to value " ++ show i)
fromEnum KERN = #{const LOG_KERN}
fromEnum USER = #{const LOG_USER}
fromEnum MAIL = #{const LOG_MAIL}
fromEnum DAEMON = #{const LOG_DAEMON}
fromEnum AUTH = #{const LOG_AUTH}
fromEnum SYSLOG = #{const LOG_SYSLOG}
fromEnum LPR = #{const LOG_LPR}
fromEnum NEWS = #{const LOG_NEWS}
fromEnum UUCP = #{const LOG_UUCP}
fromEnum CRON = #{const LOG_CRON}
fromEnum AUTHPRIV = #{const LOG_AUTHPRIV}
fromEnum FTP = #{const LOG_FTP}
fromEnum LOCAL0 = #{const LOG_LOCAL0}
fromEnum LOCAL1 = #{const LOG_LOCAL1}
fromEnum LOCAL2 = #{const LOG_LOCAL2}
fromEnum LOCAL3 = #{const LOG_LOCAL3}
fromEnum LOCAL4 = #{const LOG_LOCAL4}
fromEnum LOCAL5 = #{const LOG_LOCAL5}
fromEnum LOCAL6 = #{const LOG_LOCAL6}
fromEnum LOCAL7 = #{const LOG_LOCAL7}
-- |Options for the syslog service. Set with 'withSyslog'.
data Option
= PID -- ^ log the pid with each message
| CONS -- ^ log on the console if errors in sending
| ODELAY -- ^ delay open until first @syslog()@ (default)
| NDELAY -- ^ don't delay open
| NOWAIT -- ^ don't wait for console forks: DEPRECATED
| PERROR -- ^ log to 'stderr' as well (might be a no-op on some systems)
deriving (Eq, Bounded, Show)
instance Enum Option where
toEnum #{const LOG_PID} = PID
toEnum #{const LOG_CONS} = CONS
toEnum #{const LOG_ODELAY} = ODELAY
toEnum #{const LOG_NDELAY} = NDELAY
toEnum #{const LOG_NOWAIT} = NOWAIT
toEnum #{const LOG_PERROR} = PERROR
toEnum i = error ("Syslog.Option cannot be mapped to value " ++ show i)
fromEnum PID = #{const LOG_PID}
fromEnum CONS = #{const LOG_CONS}
fromEnum ODELAY = #{const LOG_ODELAY}
fromEnum NDELAY = #{const LOG_NDELAY}
fromEnum NOWAIT = #{const LOG_NOWAIT}
fromEnum PERROR = #{const LOG_PERROR}
-- * Haskell API to syslog
-- |Bracket an 'IO' computation between calls to '_openlog'
-- and '_closelog'. Since these settings are for the
-- /process/, multiple calls to this function will,
-- unfortunately, overwrite each other.
--
-- Example:
--
-- > main = withSyslog "my-ident" [PID, PERROR] USER $ do
-- > putStrLn "huhu"
-- > syslog Debug "huhu"
withSyslog :: String -> [Option] -> Facility -> IO a -> IO a
withSyslog ident opts facil f = do
let opt = toEnum . sum . map fromEnum $ opts
let fac = toEnum . fromEnum $ facil
withCString ident $ \p ->
bracket_ (_openlog p opt fac) (_closelog) f
-- |Log a message with the given priority.
syslog :: Priority -> String -> IO ()
syslog l msg =
withCString (safeMsg msg)
(\p -> _syslog (toEnum (fromEnum l)) p)
-- * Helpers
-- | @useSyslog ident@ @=@ @withSyslog ident [PID, PERROR] USER@
useSyslog :: String -> IO a -> IO a
useSyslog ident = withSyslog ident [PID, PERROR] USER
-- |Escape any occurances of \'@%@\' in a string, so that it
-- is safe to pass it to '_syslog'. The 'syslog' wrapper
-- does this automatically.
safeMsg :: String -> String
safeMsg [] = []
safeMsg ('%':xs) = '%' : '%' : safeMsg xs
safeMsg ( x :xs) = x : safeMsg xs
-- * Low-level C functions
foreign import ccall unsafe "closelog" _closelog ::
IO ()
foreign import ccall unsafe "openlog" _openlog ::
CString -> CInt -> CInt -> IO ()
foreign import ccall unsafe "setlogmask" _setlogmask ::
CInt -> IO CInt
foreign import ccall unsafe "syslog" _syslog ::
CInt -> CString -> IO ()