[GHC] #7473: getModificationTime gives only second-level resolution

[GHC]

#7473: getModificationTime gives only second-level resolution
----------------------------------------+----------------------------------
        Reporter:  duncan               |            Owner:
            Type:  bug                  |           Status:  new
        Priority:  normal               |        Milestone:  7.8.1
       Component:  libraries/directory  |          Version:  7.6.1
      Resolution:                       |         Keywords:
Operating System:  Unknown/Multiple     |     Architecture:
 Type of failure:  None/Unknown         |  Unknown/Multiple
       Test Case:                       |       Difficulty:  Unknown
        Blocking:                       |       Blocked By:
                                        |  Related Tickets:
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Comment (by redneb):

 I cannot reproduce that. In my experiments, `GetFileAttributesEx` works as
 expected. To test this I ran the following command (in a cygwin shell so
 that I can use sleep):

 {{{
 #!sh
 echo 1 >> test.txt && ./modtime test.txt && sleep 0.1 && echo 2 >>
 test.txt && ./modtime test.txt
 }}}

 The output was:
 {{{
 test.txt: 2013-08-29 00:30:02.4667839 UTC
 test.txt: 2013-08-29 00:30:02.5869567 UTC
 }}}

 As you can see that's full 100ns resolution.

 And here's the code for the modtime program I used above:

 {{{
 #!haskell
 import System.Win32
 import Data.Time ()
 import Data.Time.Clock.POSIX
 import System.Environment

 main :: IO ()
 main = getArgs >>= mapM_ printModTime

 printModTime :: String -> IO ()
 printModTime path = do
     fad <- getFileAttributesExStandard path
     let FILETIME ft = fadLastWriteTime fad
         mt = posixSecondsToUTCTime (fromIntegral (ft - win32_epoch_adjust)
 / 10000000)
     putStrLn (path ++ ": " ++ show mt)

 win32_epoch_adjust :: DDWORD
 win32_epoch_adjust = 116444736000000000
 }}}

 This requires my patches [1] for win32 to compile.

 [1] https://github.com/haskell/win32/pull/10

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7473#comment:11>
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