Add a flag to for the use of lstat in ReadDir

.github/workflows/haskell.yml

@@ -106,11 +106,11 @@ jobs:
             disable_sdist_build: "y"
             ignore_error: false
           # Note: use linux for warning build for convenient dev testing
-          - name: 9.10.1-Werror
+          - name: 9.10.1-Werror-lstat-readir
             ghc_version: 9.10.1
             runner: ubuntu-latest
             build: cabal
-            cabal_build_options: "--flag limit-build-mem"
+            cabal_build_options: "--flag limit-build-mem --flag force-lstat-readdir"
             cabal_version: 3.12.1.0
             disable_sdist_build: "y"
             cabal_project: cabal.project.Werror

core/src/Streamly/Internal/FileSystem/Posix/ReadDir.hsc

@@ -163,6 +163,9 @@ lstatDname parent dname = do
 {-# INLINE checkDirStatus #-}
 checkDirStatus
     :: PosixPath -> Ptr CChar -> #{type unsigned char} -> IO (Bool, Bool)
+#ifdef FORCE_LSTAT_READDIR
+checkDirStatus parent dname _ = lstatDname parent dname
+#else
 checkDirStatus parent dname dtype =
     if dtype == #const DT_UNKNOWN
     then lstatDname parent dname
@@ -171,6 +174,7 @@ checkDirStatus parent dname dtype =
         isMeta <- liftIO $ isMetaDir dname
         pure (True, isMeta)
     else pure (False, False)
+#endif
 
 -- XXX We can use getdents64 directly so that we can use array slices from the
 -- same buffer that we passed to the OS. That way we can also avoid any

core/streamly-core.cabal

@@ -152,13 +152,21 @@ flag use-folds
   manual: True
   default: False
 
+flag force-lstat-readdir
+  description: Use lstat instead of checking for dtype in ReadDir
+  manual: True
+  default: False
+
 -------------------------------------------------------------------------------
 -- Common stanzas
 -------------------------------------------------------------------------------
 
 common compile-options
     default-language: Haskell2010
 
+    if flag(force-lstat-readdir)
+      cpp-options:    -DFORCE_LSTAT_READDIR
+
     if flag(dev)
       cpp-options:    -DDEVBUILD