Merge pull request #61 from NicolasT/fix-readme-test

landlock: improve `README.lhs` test

landlock/README.md

@@ -105,14 +105,18 @@ main = withFakeRoot $ \root -> do
  readFile ("/etc" </> "hosts")
 
  where
- lookupAccessFsFlags version = case lookup version accessFsFlags of
- -- In a production implementation, we'd lookup the "best matching" flag
- -- set, not require an exact match.
+ lookupAccessFsFlags version = case lookupMax version accessFsFlags of
  Nothing -> fail "Unsupported ABI version"
  Just flags -> return flags
 
  assertPermissionDenied act = handleJust permissionDenied return $ do
  _ <- act
  fail "Expected permission error"
  permissionDenied e = if isPermissionError e then Just () else Nothing
+
+ lookupMax key = fmap snd
+ . listToMaybe
+ . reverse
+ . sort
+ . filter (\(k, _) -> key >= k)
 ```

landlock/test/ReadmeUtils.hs

@@ -4,6 +4,10 @@ module ReadmeUtils
  handleJust,
  -- Control.Monad
  unless,
+ -- Data.List
+ sort,
+ -- Data.Maybe
+ listToMaybe,
  -- System.Directory
  removeFile,
  -- System.FilePath
@@ -22,6 +26,8 @@ where
 
 import Control.Exception.Base (handleJust)
 import Control.Monad (unless)
+import Data.List (sort)
+import Data.Maybe (listToMaybe)
 import System.Directory (createDirectory, removeFile)
 import System.FilePath ((</>))
 import System.IO (IOMode (..), hPutStrLn, withFile)