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Fix createTempDirectory name generation #11872

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Merged
mergify merged 1 commit into from
May 24, 2026
+24 −12
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Fix createTempDirectory name generation #11872

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29 changes: 17 additions & 12 deletions Cabal/src/Distribution/Compat/Internal/TempFile.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,10 +10,11 @@ module Distribution.Compat.Internal.TempFile

import Distribution.Compat.Exception

import GHC.IORef (IORef, atomicModifyIORef'_, newIORef)
import System.FilePath ((</>))

import System.IO (Handle, openBinaryTempFile, openBinaryTempFileWithDefaultPermissions, openTempFile)
import System.IO.Error (isAlreadyExistsError)
import System.IO.Unsafe (unsafePerformIO)
import System.Posix.Internals (c_getpid)

#if defined(mingw32_HOST_OS) || defined(ghcjs_HOST_OS)
Expand All @@ -28,17 +29,21 @@ openNewBinaryFile = openBinaryTempFileWithDefaultPermissions
createTempDirectory :: FilePath -> String -> IO FilePath
createTempDirectory dir template = do
pid <- c_getpid
findTempName pid
where
findTempName x = do
let relpath = template ++ "-" ++ show x
dirpath = dir </> relpath
r <- tryIO $ mkPrivateDir dirpath
case r of
Right _ -> return relpath
Left e
| isAlreadyExistsError e -> findTempName (x + 1)
| otherwise -> ioError e
let findTempName = do
(counter, _) <- atomicModifyIORef'_ tempDirectoryCounter (+ 1)
let relpath = template ++ "-" ++ show pid ++ show counter
dirpath = dir </> relpath
r <- tryIO $ mkPrivateDir dirpath
case r of
Right _ -> pure relpath
Left e
| isAlreadyExistsError e -> findTempName
| otherwise -> ioError e
findTempName

tempDirectoryCounter :: IORef Word
tempDirectoryCounter = unsafePerformIO $ newIORef 0
{-# NOINLINE tempDirectoryCounter #-}

mkPrivateDir :: String -> IO ()
#if defined(mingw32_HOST_OS) || defined(ghcjs_HOST_OS)
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7 changes: 7 additions & 0 deletions changelog.d/pr-11872.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
---
synopsis: Improve name assigning for temporary folders
packages: [Cabal,cabal-install]
prs: 11872
---

Now `createTempDirectory` from `Distribution.Compat.Internal.TempFile` uses a global counter as a part of temporary folder name template, so that probing is less likely to fail. The change should be invisible for users.
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