{-# LINE 1 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}

{-# LINE 2 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
{-# LANGUAGE Safe #-}

{-# LINE 6 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
-----------------------------------------------------------------------------

-- |

-- Module      :  System.Win32.Time

-- Copyright   :  (c) Esa Ilari Vuokko, 2006

-- License     :  BSD-style (see the file LICENSE)

--

-- Maintainer  :  Esa Ilari Vuokko <ei@vuokko.info>

-- Stability   :  provisional

-- Portability :  portable

--

-- A collection of FFI declarations for interfacing with Win32 Time API.

--

-----------------------------------------------------------------------------

module System.Win32.Time where

import System.Win32.String  ( peekTStringLen, withTString )
import System.Win32.Types   ( BOOL, DDWORD, DWORD, HANDLE, LARGE_INTEGER, LCID
                            , LONG, LPCTSTR, LPCWSTR, LPTSTR, LPWSTR, UINT, WORD
                            , dwordsToDdword, ddwordToDwords, failIf
                            , failIfFalse_, failIf_ )
import System.Win32.Utils   ( trySized )

import Control.Monad    ( when, liftM3, liftM )
import Data.Word        ( Word8 )
import Foreign          ( Storable(sizeOf, alignment, peekByteOff, peek,
                                   pokeByteOff, poke)
                        , Ptr, nullPtr, castPtr, plusPtr, advancePtr
                        , with, alloca, allocaBytes, copyArray )
import Foreign.C        ( CInt(..), CWchar(..)
                        , peekCWString, withCWStringLen, withCWString )
import Foreign.Marshal.Utils (maybeWith)

#include "windows_cconv.h"




----------------------------------------------------------------

-- data types

----------------------------------------------------------------


newtype FILETIME = FILETIME DDWORD deriving (Show, Eq, Ord)

data SYSTEMTIME = SYSTEMTIME {
    wYear, wMonth, wDayOfWeek, wDay, wHour, wMinute, wSecond, wMilliseconds :: WORD }
    deriving (Show, Eq, Ord)

data TIME_ZONE_INFORMATION = TIME_ZONE_INFORMATION
    { tziBias :: LONG
    , tziStandardName :: String
    , tziStandardDate :: SYSTEMTIME
    , tziStandardBias :: LONG
    , tziDaylightName :: String
    , tziDaylightDate :: SYSTEMTIME
    , tziDaylightBias :: LONG
    } deriving (Show,Eq,Ord)

data TimeZoneId = TzIdUnknown | TzIdStandard | TzIdDaylight
    deriving (Show, Eq, Ord)

data LASTINPUTINFO = LASTINPUTINFO DWORD deriving (Show)

----------------------------------------------------------------

-- Instances

----------------------------------------------------------------


instance Storable FILETIME where
    sizeOf = const ((8))
{-# LINE 74 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
    alignment _ = 4
{-# LINE 75 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
    poke buf (FILETIME n) = do
        ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) buf low
{-# LINE 77 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 4)) buf hi
{-# LINE 78 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        where (hi,low) = ddwordToDwords n
    peek buf = do
        low <- ((\hsc_ptr -> peekByteOff hsc_ptr 0)) buf
{-# LINE 81 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        hi <- ((\hsc_ptr -> peekByteOff hsc_ptr 4)) buf
{-# LINE 82 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        return $ FILETIME $ dwordsToDdword (hi,low)

instance Storable SYSTEMTIME where
    sizeOf _ = (16)
{-# LINE 86 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
    alignment _ = 2
{-# LINE 87 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
    poke buf st = do
         ((\hsc_ptr -> pokeByteOff hsc_ptr 0))          buf (wYear st)
{-# LINE 89 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
         ((\hsc_ptr -> pokeByteOff hsc_ptr 2))         buf (wMonth st)
{-# LINE 90 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
         ((\hsc_ptr -> pokeByteOff hsc_ptr 4))     buf (wDayOfWeek st)
{-# LINE 91 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
         ((\hsc_ptr -> pokeByteOff hsc_ptr 6))           buf (wDay st)
{-# LINE 92 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
         ((\hsc_ptr -> pokeByteOff hsc_ptr 8))          buf (wHour st)
{-# LINE 93 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
         ((\hsc_ptr -> pokeByteOff hsc_ptr 10))        buf (wMinute st)
{-# LINE 94 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
         ((\hsc_ptr -> pokeByteOff hsc_ptr 12))        buf (wSecond st)
{-# LINE 95 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
         ((\hsc_ptr -> pokeByteOff hsc_ptr 14))  buf (wMilliseconds st)
{-# LINE 96 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
    peek buf = do
        year    <- ((\hsc_ptr -> peekByteOff hsc_ptr 0))        buf
{-# LINE 98 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        month   <- ((\hsc_ptr -> peekByteOff hsc_ptr 2))       buf
{-# LINE 99 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        dow     <- ((\hsc_ptr -> peekByteOff hsc_ptr 4))   buf
{-# LINE 100 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        day     <- ((\hsc_ptr -> peekByteOff hsc_ptr 6))         buf
{-# LINE 101 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        hour    <- ((\hsc_ptr -> peekByteOff hsc_ptr 8))        buf
{-# LINE 102 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        mins    <- ((\hsc_ptr -> peekByteOff hsc_ptr 10))      buf
{-# LINE 103 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        sec     <- ((\hsc_ptr -> peekByteOff hsc_ptr 12))      buf
{-# LINE 104 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        ms      <- ((\hsc_ptr -> peekByteOff hsc_ptr 14)) buf
{-# LINE 105 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        return $ SYSTEMTIME year month dow day hour mins sec ms

instance Storable TIME_ZONE_INFORMATION where
    sizeOf _ = ((172))
{-# LINE 109 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
    alignment _ = 4
{-# LINE 110 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
    poke buf tzi = do
        ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) buf (tziBias tzi)
{-# LINE 112 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 68)) buf (tziStandardDate tzi)
{-# LINE 113 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 84)) buf (tziStandardBias tzi)
{-# LINE 114 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 152)) buf (tziDaylightDate tzi)
{-# LINE 115 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 168)) buf (tziDaylightBias tzi)
{-# LINE 116 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        write buf ((4)) (tziStandardName tzi)
{-# LINE 117 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        write buf ((88)) (tziDaylightName tzi)
{-# LINE 118 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        where
            write buf_ offset str = withCWStringLen str $ \(c_str,len) -> do
                when (len>31) $ fail "Storable TIME_ZONE_INFORMATION.poke: Too long string."
                let len'  = len * sizeOf (undefined :: CWchar)
                    start = (advancePtr (castPtr buf_) offset)
                    end   = advancePtr start len'
                copyArray start (castPtr c_str :: Ptr Word8) len'
                poke (castPtr end) (0 :: CWchar)

    peek buf = do
        bias <- ((\hsc_ptr -> peekByteOff hsc_ptr 0))         buf
{-# LINE 129 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        sdat <- ((\hsc_ptr -> peekByteOff hsc_ptr 68)) buf
{-# LINE 130 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        sbia <- ((\hsc_ptr -> peekByteOff hsc_ptr 84)) buf
{-# LINE 131 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        ddat <- ((\hsc_ptr -> peekByteOff hsc_ptr 152)) buf
{-# LINE 132 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        dbia <- ((\hsc_ptr -> peekByteOff hsc_ptr 168)) buf
{-# LINE 133 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        snam <- peekCWString (plusPtr buf ((4)))
{-# LINE 134 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        dnam <- peekCWString (plusPtr buf ((88)))
{-# LINE 135 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        return $ TIME_ZONE_INFORMATION bias snam sdat sbia dnam ddat dbia

instance Storable LASTINPUTINFO where
    sizeOf = const ((8))
{-# LINE 139 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
    alignment = sizeOf
    poke buf (LASTINPUTINFO t) = do
        ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) buf (((8)) :: UINT)
{-# LINE 142 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 4)) buf t
{-# LINE 143 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
    peek buf = do
        t <- ((\hsc_ptr -> peekByteOff hsc_ptr 4)) buf
{-# LINE 145 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        return $ LASTINPUTINFO t

foreign import WINDOWS_CCONV "windows.h GetSystemTime"
    c_GetSystemTime :: Ptr SYSTEMTIME -> IO ()
getSystemTime :: IO SYSTEMTIME
getSystemTime = alloca $ \res -> do
    c_GetSystemTime res
    peek res

foreign import WINDOWS_CCONV "windows.h SetSystemTime"
    c_SetSystemTime :: Ptr SYSTEMTIME -> IO BOOL
setSystemTime :: SYSTEMTIME -> IO ()
setSystemTime st = with st $ \c_st -> failIf_ not "setSystemTime: SetSystemTime" $
    c_SetSystemTime c_st

foreign import WINDOWS_CCONV "windows.h GetSystemTimeAsFileTime"
    c_GetSystemTimeAsFileTime :: Ptr FILETIME -> IO ()
getSystemTimeAsFileTime :: IO FILETIME
getSystemTimeAsFileTime = alloca $ \ret -> do
    c_GetSystemTimeAsFileTime ret
    peek ret

foreign import WINDOWS_CCONV "windows.h GetLocalTime"
    c_GetLocalTime :: Ptr SYSTEMTIME -> IO ()
getLocalTime :: IO SYSTEMTIME
getLocalTime = alloca $ \res -> do
    c_GetLocalTime res
    peek res

foreign import WINDOWS_CCONV "windows.h SetLocalTime"
    c_SetLocalTime :: Ptr SYSTEMTIME -> IO BOOL
setLocalTime :: SYSTEMTIME -> IO ()
setLocalTime st = with st $ \c_st -> failIf_ not "setLocalTime: SetLocalTime" $
    c_SetLocalTime c_st

foreign import WINDOWS_CCONV "windows.h GetSystemTimeAdjustment"
    c_GetSystemTimeAdjustment :: Ptr DWORD -> Ptr DWORD -> Ptr BOOL -> IO BOOL
getSystemTimeAdjustment :: IO (Maybe (Int, Int))
getSystemTimeAdjustment = alloca $ \ta -> alloca $ \ti -> alloca $ \enabled -> do
    failIf_ not "getSystemTimeAdjustment: GetSystemTimeAdjustment" $
        c_GetSystemTimeAdjustment ta ti enabled
    enabled' <- peek enabled
    if enabled'
        then do
            ta' <- peek ta
            ti' <- peek ti
            return $ Just (fromIntegral ta', fromIntegral ti')
        else return Nothing

foreign import WINDOWS_CCONV "windows.h GetTickCount" getTickCount :: IO DWORD

foreign import WINDOWS_CCONV unsafe "windows.h GetLastInputInfo"
  c_GetLastInputInfo :: Ptr LASTINPUTINFO -> IO Bool
getLastInputInfo :: IO DWORD
getLastInputInfo =
  with (LASTINPUTINFO 0) $ \lii_p -> do
  failIfFalse_ "GetLastInputInfo" $ c_GetLastInputInfo lii_p
  LASTINPUTINFO lii <- peek lii_p
  return lii

getIdleTime :: IO Integer
getIdleTime = do
  lii <- getLastInputInfo
  now <- getTickCount
  return $ fromIntegral $ now - lii

foreign import WINDOWS_CCONV "windows.h SetSystemTimeAdjustment"
    c_SetSystemTimeAdjustment :: DWORD -> BOOL -> IO BOOL
setSystemTimeAdjustment :: Maybe Int -> IO ()
setSystemTimeAdjustment ta =
    failIf_ not "setSystemTimeAjustment: SetSystemTimeAdjustment" $
        c_SetSystemTimeAdjustment time disabled
    where
        (time,disabled) = case ta of
            Nothing -> (0,True)
            Just x  -> (fromIntegral x,False)

foreign import WINDOWS_CCONV "windows.h GetTimeZoneInformation"
    c_GetTimeZoneInformation :: Ptr TIME_ZONE_INFORMATION -> IO DWORD
getTimeZoneInformation :: IO (TimeZoneId, TIME_ZONE_INFORMATION)
getTimeZoneInformation = alloca $ \tzi -> do
    tz <- failIf (==(4294967295)) "getTimeZoneInformation: GetTimeZoneInformation" $
{-# LINE 227 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        c_GetTimeZoneInformation tzi
    tzi' <- peek tzi
    return . flip (,) tzi' $ case tz of
        (0)   -> TzIdUnknown
{-# LINE 231 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        (1)  -> TzIdStandard
{-# LINE 232 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        (2)  -> TzIdDaylight
{-# LINE 233 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}
        _                               -> TzIdUnknown   -- to remove warning


foreign import WINDOWS_CCONV "windows.h SystemTimeToFileTime"
    c_SystemTimeToFileTime :: Ptr SYSTEMTIME -> Ptr FILETIME -> IO BOOL
systemTimeToFileTime :: SYSTEMTIME -> IO FILETIME
systemTimeToFileTime s = with s $ \c_s -> alloca $ \ret -> do
    failIf_ not "systemTimeToFileTime: SystemTimeToFileTime" $
        c_SystemTimeToFileTime c_s ret
    peek ret

foreign import WINDOWS_CCONV "windows.h FileTimeToSystemTime"
    c_FileTimeToSystemTime :: Ptr FILETIME -> Ptr SYSTEMTIME -> IO BOOL
fileTimeToSystemTime :: FILETIME -> IO SYSTEMTIME
fileTimeToSystemTime s = with s $ \c_s -> alloca $ \ret -> do
    failIf_ not "fileTimeToSystemTime: FileTimeToSystemTime" $
        c_FileTimeToSystemTime c_s ret
    peek ret

foreign import WINDOWS_CCONV "windows.h GetFileTime"
    c_GetFileTime :: HANDLE -> Ptr FILETIME -> Ptr FILETIME -> Ptr FILETIME -> IO BOOL
getFileTime :: HANDLE -> IO (FILETIME,FILETIME,FILETIME)
getFileTime h = alloca $ \crt -> alloca $ \acc -> alloca $ \wrt -> do
    failIf_ not "getFileTime: GetFileTime" $ c_GetFileTime h crt acc wrt
    liftM3 (,,) (peek crt) (peek acc) (peek wrt)

foreign import WINDOWS_CCONV "windows.h SetFileTime"
    c_SetFileTime :: HANDLE -> Ptr FILETIME -> Ptr FILETIME -> Ptr FILETIME -> IO BOOL
setFileTime :: HANDLE -> FILETIME -> FILETIME -> FILETIME -> IO ()
setFileTime h crt acc wrt = with crt $
    \c_crt -> with acc $
    \c_acc -> with wrt $
    \c_wrt -> do
      failIf_ not "setFileTime: SetFileTime" $ c_SetFileTime h c_crt c_acc c_wrt

foreign import WINDOWS_CCONV "windows.h FileTimeToLocalFileTime"
    c_FileTimeToLocalFileTime :: Ptr FILETIME -> Ptr FILETIME -> IO BOOL
fileTimeToLocalFileTime :: FILETIME -> IO FILETIME
fileTimeToLocalFileTime ft = with ft $ \c_ft -> alloca $ \res -> do
    failIf_ not "fileTimeToLocalFileTime: FileTimeToLocalFileTime"
        $ c_FileTimeToLocalFileTime c_ft res
    peek res

foreign import WINDOWS_CCONV "windows.h LocalFileTimeToFileTime"
    c_LocalFileTimeToFileTime :: Ptr FILETIME -> Ptr FILETIME -> IO BOOL
localFileTimeToFileTime :: FILETIME -> IO FILETIME
localFileTimeToFileTime ft = with ft $ \c_ft -> alloca $ \res -> do
    failIf_ not "localFileTimeToFileTime: LocalFileTimeToFileTime"
        $ c_LocalFileTimeToFileTime c_ft res
    peek res

{-
-- Windows XP SP1
foreign import WINDOWS_CCONV "windows.h GetSystemTimes"
    c_GetSystemTimes :: Ptr FILETIME -> Ptr FILETIME -> Ptr FILETIME -> IO BOOL
getSystemTimes :: IO (FILETIME,FILETIME,FILETIME)
getSystemTimes = alloca $ \idle -> alloca $ \kernel -> alloca $ \user -> do
    failIf not "getSystemTimes: GetSystemTimes" $ c_GetSystemTimes idle kernel user
    liftM3 (,,) (peek idle) (peek kernel) (peek user)
-}

{-
-- Windows XP
foreign import WINDOWS_CCONV "windows.h SystemTimeToTzSpecificLocalTime"
    c_SystemTimeToTzSpecificLocalTime :: Ptr TIME_ZONE_INFORMATION -> Ptr SYSTEMTIME -> Ptr SYSTEMTIME -> IO BOOL
systemTimeToTzSpecificLocalTime :: TIME_ZONE_INFORMATION -> SYSTEMTIME -> IO SYSTEMTIME
systemTimeToTzSpecificLocalTime tzi st = with tzi $ \tzi -> with st $ \st -> alloca $ \res -> do
    failIf not "systemTimeToTzSpecificLocalTime: SystemTimeToTzSpecificLocalTime" $
        c_SystemTimeToTzSpecificLocalTime tzi st res
    peek res

foreign import WINDOWS_CCONV "windows.h TzSpecificLocalTimeToSystemTime"
    c_TzSpecificLocalTimeToSystemTime :: Ptr TIME_ZONE_INFORMATION -> Ptr SYSTEMTIME -> Ptr SYSTEMTIME -> IO BOOL
tzSpecificLocalTimeToSystemTime :: TIME_ZONE_INFORMATION -> SYSTEMTIME -> IO SYSTEMTIME
tzSpecificLocalTimeToSystemTime tzi st = with tzi $ \tzi -> with st $ \st -> alloca $ \res -> do
    failIf not "tzSpecificLocalTimeToSystemTime: TzSpecificLocalTimeToSystemTime" $
        c_TzSpecificLocalTimeToSystemTime tzi st res
    peek res
-}

foreign import WINDOWS_CCONV "windows.h QueryPerformanceFrequency"
    c_QueryPerformanceFrequency :: Ptr LARGE_INTEGER -> IO BOOL
queryPerformanceFrequency :: IO Integer
queryPerformanceFrequency = alloca $ \res -> do
    failIf_ not "queryPerformanceFrequency: QueryPerformanceFrequency" $
        c_QueryPerformanceFrequency res
    liftM fromIntegral $ peek res

foreign import WINDOWS_CCONV "windows.h QueryPerformanceCounter"
    c_QueryPerformanceCounter:: Ptr LARGE_INTEGER -> IO BOOL
queryPerformanceCounter:: IO Integer
queryPerformanceCounter= alloca $ \res -> do
    failIf_ not "queryPerformanceCounter: QueryPerformanceCounter" $
        c_QueryPerformanceCounter res
    liftM fromIntegral $ peek res

type GetTimeFormatFlags = DWORD
lOCALE_NOUSEROVERRIDE  :: GetTimeFormatFlags
lOCALE_NOUSEROVERRIDE  =  2147483648
lOCALE_USE_CP_ACP      :: GetTimeFormatFlags
lOCALE_USE_CP_ACP      =  1073741824
tIME_NOMINUTESORSECONDS  :: GetTimeFormatFlags
tIME_NOMINUTESORSECONDS  =  1
tIME_NOSECONDS         :: GetTimeFormatFlags
tIME_NOSECONDS         =  2
tIME_NOTIMEMARKER      :: GetTimeFormatFlags
tIME_NOTIMEMARKER      =  4
tIME_FORCE24HOURFORMAT :: GetTimeFormatFlags
tIME_FORCE24HOURFORMAT =  8

{-# LINE 337 "libraries\\Win32\\System\\Win32\\Time.hsc" #-}

getTimeFormatEx :: Maybe String
                -> GetTimeFormatFlags
                -> Maybe SYSTEMTIME
                -> Maybe String
                -> IO String
getTimeFormatEx locale flags st fmt =
    maybeWith withTString locale $ \c_locale ->
        maybeWith with st $ \c_st ->
            maybeWith withTString fmt $ \c_fmt -> do
                let c_func = c_GetTimeFormatEx c_locale flags c_st c_fmt
                trySized "GetTimeFormatEx" c_func
foreign import WINDOWS_CCONV "windows.h GetTimeFormatEx"
    c_GetTimeFormatEx :: LPCWSTR
                      -> GetTimeFormatFlags
                      -> Ptr SYSTEMTIME
                      -> LPCWSTR
                      -> LPWSTR
                      -> CInt
                      -> IO CInt

foreign import WINDOWS_CCONV "windows.h GetTimeFormatW"
    c_GetTimeFormat :: LCID -> GetTimeFormatFlags -> Ptr SYSTEMTIME -> LPCTSTR -> LPTSTR -> CInt -> IO CInt
getTimeFormat :: LCID -> GetTimeFormatFlags -> Maybe SYSTEMTIME -> Maybe String -> IO String
getTimeFormat locale flags st fmt =
    maybeWith with st $ \c_st ->
    maybeWith withCWString fmt $ \c_fmt -> do
        size <- c_GetTimeFormat locale flags c_st c_fmt nullPtr 0
        allocaBytes ((fromIntegral size) * (sizeOf (undefined::CWchar))) $ \out -> do
            size' <- failIf (==0) "getTimeFormat: GetTimeFormat" $
                c_GetTimeFormat locale flags c_st c_fmt (castPtr out) size
            peekTStringLen (out,fromIntegral size')