[GHC] #7985: Allow openFile on unknown file type

[GHC]

#7985: Allow openFile on unknown file type
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        Reporter:  singpolyma        |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Core Libraries    |              Version:  7.6.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by rwbarton):

 I believe these cryptic communications refer to the following function.
 {{{
 statGetType :: Ptr CStat -> IO IODeviceType
 statGetType p_stat = do
   c_mode <- st_mode p_stat :: IO CMode
   case () of
       _ | s_isdir c_mode        -> return Directory
         | s_isfifo c_mode || s_issock c_mode || s_ischr  c_mode
                                 -> return Stream
         | s_isreg c_mode        -> return RegularFile
          -- Q: map char devices to RawDevice too?
         | s_isblk c_mode        -> return RawDevice
         | otherwise             -> ioError ioe_unknownfiletype
 }}}
 These are all the types of file defined by POSIX, but I suppose a system
 could add others.

 But it's unclear what to do here. What should we return for, say,
 `hIsSeekable` if you opened such a file? Just guessing once and for all
 that files of unknown type are seekable (or not seekable) doesn't seem
 right. Haven't looked into what else the file type is used for.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7985#comment:8>
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