[GHC] #2109: hIsEOF blocks when applied to a non-closed socket with no input available

[GHC]

#2109: hIsEOF blocks when applied to a non-closed socket with no input available
--------------------------------------+-------------------------------------
    Reporter:  Mads                   |       Owner:                
        Type:  bug                    |      Status:  new           
    Priority:  normal                 |   Component:  libraries/base
     Version:  6.8.2                  |    Severity:  normal        
    Keywords:  hIsEOF blocks sockets  |    Testcase:                
Architecture:  Multiple               |          Os:  Unknown       
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 As shown with the attached test-programs, hIsEOF will block when
 applied to a socket-handle that is not closed and has no input
 available.

 I believe that hIsEOF blocks, as it calls hLookAhead (see
 libraries/base/GHC/Handle.hs), which blocks when there is no
 input. Note that this is only a problem when using sockets, as (local)
 files will either be EOF or has some content.

 If hIsEOF blocking nature is expected behaviour, then I think it
 should be noted in the haddock-documentation, as it seems
 non-obvious. Especially, as it will seem non-blocking when working
 with files.

 I am using GHC 6.8.2 on a Debian Linux box.

 To reproduce the bug, then first compile the test programs using the
 accompanying makefile. Then start the server. After that the
 client. As can be seen, the server will hang.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2109>
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