From 22ddeeadccacda60d010913491bbc9f63b68b2dc Mon Sep 17 00:00:00 2001
From: Julian Ospald <hasufell@posteo.de>
Date: Sat, 18 Jan 2020 18:43:55 +0100
Subject: [PATCH] Add isSpecialDirectoryEntry

---
 hpath-filepath/src/System/Posix/FilePath.hs | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/hpath-filepath/src/System/Posix/FilePath.hs b/hpath-filepath/src/System/Posix/FilePath.hs
index dfe3d5d..40a09c6 100644
--- a/hpath-filepath/src/System/Posix/FilePath.hs
+++ b/hpath-filepath/src/System/Posix/FilePath.hs
@@ -73,6 +73,7 @@ module System.Posix.FilePath (
 , isAbsolute
 , isValid
 , makeValid
+, isSpecialDirectoryEntry
 , isFileName
 , hasParentDir
 , hiddenFile
@@ -724,6 +725,21 @@ makeValid path
   | otherwise    = BS.map (\x -> if x == _nul then _underscore else x) path
 
 
+-- | Is a FilePath valid, i.e. could you create a file like it?
+--
+-- >>> isSpecialDirectoryEntry "."
+-- True
+-- >>> isSpecialDirectoryEntry ".."
+-- True
+-- >>> isSpecialDirectoryEntry "/random_ path:*"
+-- False
+isSpecialDirectoryEntry :: RawFilePath -> Bool
+isSpecialDirectoryEntry filepath
+  | BS.pack [_period, _period] == filepath = True
+  | BS.pack [_period] == filepath          = True
+  | otherwise                              = False
+
+
 -- | Is the given path a valid filename? This includes
 -- "." and "..".
 --