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{-
Before running this, check that /tmp/test does not exist and
contain something important. Then do:
$ touch /tmp/test
If you do:
$ runhaskell Test.hs
it will work. If you do:
$ runhaskell Test.hs fail
it will fail every time with:
Test.hs: writeFile: /tmp/test: openFile: resource busy (file is locked)
-}
import Control.Monad
import System.Directory
import System.IO
import System.Environment
-- Used by test2:
-- import System.Posix.IO
fp = "2122-test"
main :: IO ()
main = do
writeFile fp "test"
test True
-- fails everytime when causeFailure is True in GHCi, with runhaskell,
-- or when compiled.
test :: Bool -> IO ()
test causeFailure =
do h1 <- openFile fp ReadMode `Prelude.catch` (\e -> error ("openFile 1: " ++ show e))
when causeFailure $ do
h2 <- openFile fp ReadMode `Prelude.catch` (\e -> error ("openFile 2: " ++ show e))
hClose h2
hClose h1
removeFile fp
writeFile fp (show [1..100]) `Prelude.catch` (\e -> error ("writeFile: " ++ show e))
{-
-- this version never fails (except in GHCi, if test has previously failed).
-- probably because openFd does not try to lock the file
test2 :: Bool -> IO ()
test2 causeFailure =
do fd1 <- openFd fp ReadOnly Nothing defaultFileFlags `Prelude.catch` (\e -> error ("openFile 1: " ++ show e))
when causeFailure $ do
fd2 <- openFd fp ReadOnly Nothing defaultFileFlags `Prelude.catch` (\e -> error ("openFile 2: " ++ show e))
closeFd fd2
closeFd fd1
removeFile fp
writeFile fp (show [1..100]) `Prelude.catch` (\e -> error ("writeFile: " ++ show e))
-}
{-
-- fails sometimes when run repeated in GHCi, but seems fine with
-- runhaskell or compiled
test3 :: IO ()
test3 =
do h1 <- openFile fp ReadMode `Prelude.catch` (\e -> error ("openFile 1: " ++ show e))
h2 <- openFile fp ReadMode `Prelude.catch` (\e -> error ("openFile 2: " ++ show e))
removeFile fp
writeFile fp (show [1..100]) `Prelude.catch` (\e -> error ("writeFile: " ++ show e))
print =<< hGetContents h1
print =<< hGetContents h2
hClose h2
hClose h1
-}
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