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removeFile did not remove file or throw errors. #12

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Magicloud opened this issue Dec 23, 2014 · 10 comments
Closed

removeFile did not remove file or throw errors. #12

Magicloud opened this issue Dec 23, 2014 · 10 comments
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type: x-intended-behavior The described behavior is working as intended.

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@Magicloud
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In the following code, in withTemp function, after removeFile fp, the temp file was still there. I tried to use try to catch IOException that may throw by removeFile. I just got Right ().

It is Ubuntu Trusty, ghc 7.8.3, directory 1.2.1.0.

import Network.Curl
import System.Posix.Temp
import System.Directory
import System.IO
import Text.HTML.DOM
import Text.XML
import System.FilePath
import Control.Exception

type PostField = (String, String)

withTemp :: String -> (FilePath -> IO a) -> IO a
withTemp prefix f = do
  tmp <- getTemporaryDirectory
  (fp, h) <- mkstemp $ tmp </> prefix
  hClose h
  finally (f fp) $ removeFile fp

curl :: (CurlBuffer ty) => URLString -> Maybe [PostField] -> IO (Either CurlCode ty)
curl url values = do
  let mPf = fmap (map (\(k, v) -> k ++ "=" ++ v)) values
  (cc, ty) <- withTemp "Cookie" $ \tmp -> withCurlDo $
    let curlOpts_ = [ CurlHttpAuth [HttpAuthAny]
                    , CurlUserPwd ":"
                    , CurlCookieFile tmp
                    , CurlCookieJar tmp
                    , CurlFollowLocation True
                    , CurlUnrestrictedAuth True ]
        curlOpts = case mPf of
                     Nothing -> curlOpts_
                     Just pf -> (CurlPostFields pf) : curlOpts_
    in curlGetString_ url curlOpts
  return $ if cc == CurlOK
              then Right ty
              else Left cc
@hvr hvr added the type: a-bug The described behavior is not working as intended. label Jan 16, 2015
@hvr
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hvr commented Jan 16, 2015

I wonder if this is related to #4

@Rufflewind
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I tried the test program and I don't believe the problem is related to directory. The temporary file appears to have been created asynchronously, long after removeFile has completed. There is a roughly 3 second delay before the file appears on the filesystem even though the function has completed execution.

@UnkindPartition
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Why would the file be created asynchronously?

Anyway, I can't reproduce the issue on Fedora 21 (and same ghc/directory versions as OP's) with

main = curl "http://google.com" Nothing >>= (print :: Either CurlCode String -> IO ())

@Rufflewind
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Why would the file be created asynchronously?

I don't know. Something odd about the curl library. Perhaps unsafeInterleaveIO? The problem couldn't be reproduced unless I forced the result to NF with fmap length.

Polling the existence of the file at 1 sec intervals:

withTemp: does /tmp/CookieYcViim exist?  True
withTemp: file /tmp/CookieYcViim has been removed
main: does /tmp/CookieYcViim exist?  False
main: curl returned (truncated):
  Right "<!doctype html><html itemscope=\"\" itemtype=\"http://schema.org/WebPage\" lang=\"en\""
  Right 52318
main: does /tmp/CookieYcViim exist?  False
main: does /tmp/CookieYcViim exist?  True
main: does /tmp/CookieYcViim exist?  True
main: does /tmp/CookieYcViim exist?  True

Here's the code I used:

import Control.Concurrent
import Control.Monad
import Network.Curl
import System.Posix.Temp
import System.Directory
import System.IO
import System.FilePath
import Control.Exception

type PostField = (String, String)

withTemp :: String -> (FilePath -> IO a) -> IO a
withTemp prefix f = do
  tmp <- getTemporaryDirectory
  (fp, h) <- mkstemp $ tmp </> prefix
  hClose h
  finally (f fp) $ do
    putStr ("withTemp: does " ++ fp ++ " exist?  ")
    print =<< doesFileExist fp
    threadDelay 1000000
    removeFile fp
    putStrLn ("withTemp: file " ++ fp ++ " has been removed")

curl :: URLString -> Maybe [PostField] -> IO (FilePath, Either CurlCode String)
curl url values = do
  let mPf = fmap (map (\(k, v) -> k ++ "=" ++ v)) values
  (tmp, (cc, ty)) <- withTemp "Cookie" $ \tmp -> fmap (\x -> (tmp, x)) $ withCurlDo $
    let curlOpts_ = [ CurlHttpAuth [HttpAuthAny]
                    , CurlUserPwd ":"
                    , CurlCookieFile tmp
                    , CurlCookieJar tmp
                    , CurlFollowLocation True
                    , CurlUnrestrictedAuth True ]
        curlOpts = case mPf of
                     Nothing -> curlOpts_
                     Just pf -> (CurlPostFields pf) : curlOpts_
    in curlGetString_ url curlOpts
  return $ (,) tmp $ if cc == CurlOK
              then Right ty
              else Left cc

main :: IO ()
main = do
  (path, result) <- curl "http://google.com" Nothing

  putStr ("main: does " ++ path ++ " exist?  ")
  print =<< doesFileExist path
  threadDelay 1000000

  putStr "main: curl returned (truncated):\n  "
  print (take 80 `fmap` result)
  putStr "  "
  print (length `fmap` result) -- must force result to NF completely!

  forever $ do
    putStr ("main: does " ++ path ++ " exist?  ")
    print =<< doesFileExist path
    threadDelay 1000000

Marking as invalid since the problem is not due to directory.

@Rufflewind Rufflewind added type: x-intended-behavior The described behavior is working as intended. and removed type: a-bug The described behavior is not working as intended. labels Feb 18, 2015
@argiopetech
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Seeing as how this is a "can't fix, won't fix", is there a compelling reason to keep it open?

@Rufflewind
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I left it open to see if anyone else has any comments.

@UnkindPartition
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@Rufflewind thanks for the test case, but again, I can't reproduce it. On my system, it never gets to True for the second time.

@Rufflewind
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@feuerbach I'm using a slightly different version of GHC (7.8.4) but I doubt that's the source of the problem. Mind if I ask what version of libcurl and curl you use? I use curl-1.3.8 and libcurl-7.40.0.

Edit: apparently the version number on libcurl.so is wrong.

@UnkindPartition
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curl 1.3.8.1, libcurl 7.37.0

@Rufflewind
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Hrm, I'm not sure what the problem is. I built and linked against curl-7.37.0 and the test case still works for me. Furthermore, curl-1.3.8.1 looks virtually identical to curl-1.3.8 modulo some documentation changes and a version bump.

bgamari pushed a commit to bgamari/directory that referenced this issue Jul 29, 2016
@ndmitchell
Merge pull request haskell#29 from thomie/bugFixes
c9c1d58 
Bug fixes for normalise haskell#12
bgamari pushed a commit to bgamari/directory that referenced this issue Jul 29, 2016
@ndmitchell
haskell#12, add notes on why FilePath isn't abstract
59b8639
bgamari pushed a commit to bgamari/directory that referenced this issue Jul 29, 2016
@ndmitchell
haskell#12, note that this library helps move towards an abstract fil…
10553c6 
…epath type
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@UnkindPartition @hvr @argiopetech @Magicloud @Rufflewind