#7473: getModificationTime gives only second-level resolution
-----------------------------+----------------------------------------------
Reporter: duncan | Owner:
Type: bug | Status: new
Priority: normal | Component: libraries/directory
Version: 7.6.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: None/Unknown | Blockedby:
Blocking: | Related:
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The `System.Directory.getModificationTime` function only returns time with
second-level granularity. This is no good for applications like `ghc
--make` where we need to compare file timestamps.
The fix should be simple, here's a patch (compiles but not tested) that
should fix it for Unix, for Windows we will need a different fix, probably
using the Win32 API directly, rather than the mingw C api.
{{{
diff --git a/System/Directory.hs b/System/Directory.hs
index cfe7cd9..f27bfc4 100644
--- a/System/Directory.hs
+++ b/System/Directory.hs
@@ -995,14 +995,14 @@ The operation may fail with:
getModificationTime :: FilePath -> IO UTCTime
getModificationTime name = do
#ifdef mingw32_HOST_OS
- -- ToDo: use Win32 API
+ -- ToDo: use Win32 API so we can get sub-second resolution
withFileStatus "getModificationTime" name $ \ st -> do
modificationTime st
#else
stat <- Posix.getFileStatus name
- let mod_time :: Posix.EpochTime
- mod_time = Posix.modificationTime stat
- return $ posixSecondsToUTCTime $ realToFrac mod_time
+ let mod_time :: POSIXTime
+ mod_time = Posix.modificationTimeHiRes stat
+ return $! posixSecondsToUTCTime mod_time
#endif
#endif /* __GLASGOW_HASKELL__ */
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7473>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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