Merge pull request #6745 from commercialhaskell/fix6744

Fix #6744 Use system temp dir when on dest drive

Author: mpilgrem

ChangeLog.md

@@ -29,6 +29,9 @@ Bug fixes:
   environment variable. In previous versions of Stack, this affected
   `stack script` when copying a pre-compiled package from another package
   database.
+* On Windows, when decompressing, and extracting tools, from archive files,
+  Stack uses the system temporary directory, rather than the root of the
+  destination drive, if the former is on the destination drive.
 
 ## v3.5.1 - 2025-03-29
 

doc/commands/setup_command.md

@@ -103,8 +103,13 @@ and the command are inconsistent and take no action.
 
     Stack uses the 7-Zip tool to decompress, and extract tools from, downloaded
     archive files. Aiming to avoid long file paths, Stack does so in a temporary
-    directory (named `stack-tmp-<hash>`) in the root of the drive of the final
-    destination. Consequently, Stack needs permission to create a directory in
-    that location. A Windows user account of type Administrator will have
-    permission to create a directory in the root of the system drive (`C:\`, by
-    convention) but a Standard user account may well not have permission.
+    directory (named `stack-tmp-<hash>`) on the drive of the final destination
+    (either in the system temporary directory, where applicable, or the root of
+    the drive). Consequently, Stack needs permission to create a directory in
+    that location.
+
+    A Windows user account will usually have permission to create a directory in
+    the system temporary directory. A Windows user account of type Administrator
+    will have permission to create a directory in the root of the system drive
+    (`C:\`, by convention) but a Standard user account may well not have
+    permission.

src/Stack/Setup.hs

@@ -82,9 +82,9 @@ import           Path.CheckInstall ( warnInstallSearchPathIssues )
 import           Path.Extra ( toFilePathNoTrailingSep )
 import           Path.IO
                    ( canonicalizePath, doesFileExist, ensureDir, executable
-                   , getPermissions, ignoringAbsence, listDir, removeDirRecur
-                   , removeFile, renameDir, renameFile, resolveFile'
-                   , withTempDir
+                   , getPermissions, getTempDir, ignoringAbsence, listDir
+                   , removeDirRecur, removeFile, renameDir, renameFile
+                   , resolveFile', withTempDir
                    )
 import           RIO.List
                    ( headMaybe, intercalate, intersperse, isPrefixOf
@@ -2454,19 +2454,26 @@ withUnpackedTarball7z name si archiveFile archiveType destDir = do
       Nothing -> prettyThrowIO $ TarballFileInvalid name archiveFile
       Just x -> parseRelFile $ T.unpack x
   run7z <- setup7z si
-  -- We use a short name for the temporary directory to reduce the risk of a
-  -- filepath length of more than 260 characters, which can be problematic for
-  -- 7-Zip even if Long Filepaths are enabled on Windows.
+  -- We aim to reduce the risk of a filepath length of more than 260 characters,
+  -- which can be problematic for 7-Zip if Windows is not 'long file paths'
+  -- enabled. We use a short name for the temporary directory ...
   let tmpName = "stack-tmp"
       destDrive = takeDrive destDir
   ensureDir (parent destDir)
+  tempDrive <- takeDrive <$> getTempDir
+  -- We use a temporary directory with likely a short absolute path ...
+  let withTempDir' = if tempDrive == destDrive
+        then
+          -- We use the system temporary directory if we can, as a Standard user
+          -- may well not have permission to create a directory in the root of
+          -- the system drive.
+          withSystemTempDir
+        else
+          -- Otherwise we use a temporary directory in the root of the
+          -- destination drive.
+          withTempDir destDrive
   withRunInIO $ \run ->
-  -- We use a temporary directory in the same drive as that of 'destDir' to
-  -- reduce the risk of a filepath length of more than 260 characters, which can
-  -- be problematic for 7-Zip even if Long Filepaths are enabled on Windows. We
-  -- do not use the system temporary directory as it may be on a different
-  -- drive.
-    withTempDir destDrive tmpName $ \tmpDir ->
+    withTempDir' tmpName $ \tmpDir ->
       run $ do
         liftIO $ ignoringAbsence (removeDirRecur destDir)
         run7z tmpDir archiveFile