#3231: Permission denied error with runProcess/openFile
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Reporter: NeilMitchell | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.10.2
Severity: normal | Resolution:
Keywords: | Testcase:
Os: Windows | Architecture: Unknown/Multiple
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Comment (by claus):
Thanks for bringing this from rumour to concrete code. Sounded like a good
example to try out ProcessExplorer on!-) I tried the following variation,
to give me some control and time to see the open handles:
{{{
module Main() where
import Control.Concurrent
import System.IO
import System.Directory
import System.Process
import Control.Exception(bracket)
my_system str = do
(_,_,_,p) <- createProcess c
waitForProcess p
where c = CreateProcess { cmdspec = ShellCommand str,
cwd = Nothing,
env = Nothing,
std_in = Inherit,
std_out = Inherit,
std_err = Inherit,
close_fds = True }
main = do
v <- newEmptyMVar
hSetBuffering stdout NoBuffering
forkIO $ f v "foo1.txt"
forkIO $ f v "foo2.txt"
threadDelay $ 100*1000000
putStrLn "Finished successfully"
f v file = do
bracket (openFile file WriteMode)
(hClose)
(\h->do hPutStrLn h file
hPutStr stderr (">"++file++"< ")
my_system "sleep 5s"
)
-- takeMVar v
hPutStr stderr ("<"++file++"> ")
my_system "sleep 5s"
removeFile file
f v file
}}}
It seems that no matter what I set `close_fds` to (default `False`?), both
GHC and one of its two children sometimes hang on to both files, while the
other child hangs on to `foo1` only?? Also, there is occasionally a new
pair of children, before the old pair is gone (this tends to preceed the
access error). Are these just ProcessExplorer sampling artifacts, am I
misreading the data, or is there something else going on (ghc
6.11.20090320)?
Btw, after Duncan's remark, I looked up [http://msdn.microsoft.com/en-
us/library/aa363915(VS.85).aspx DeleteFile] and found these two -seemingly
contradictory- remarks:
The DeleteFile function fails if an application attempts to delete a file
that is open for normal I/O or as a memory-mapped file.
The DeleteFile function marks a file for deletion on close. Therefore,
the file deletion does not occur until the last handle to the file is
closed. Subsequent calls to CreateFile to open the file fail with
ERROR_ACCESS_DENIED.
Could anyone please explain what that second remark means, given the
first? What is the non-normal I/O it seems to apply to?
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3231#comment:8>
GHC <http://www.haskell.org/ghc/>
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