Merge pull request #4754 from clayrat/patch-15

Fix file handle leaks and simplify code

libs/prelude/Prelude/File.idr

@@ -3,6 +3,7 @@ module Prelude.File
 import Builtins
 import Prelude.List
 import Prelude.Maybe
+import Prelude.Functor
 import Prelude.Monad
 import Prelude.Chars
 import Prelude.Strings
@@ -80,7 +81,7 @@ do_ferror h = foreign FFI_C "fileError" (Ptr -> IO Int) h
 export
 ferror : File -> IO Bool
 ferror (FHandle h) = do err <- do_ferror h
-                        pure (not (err == 0))
+                        pure (err /= 0)
 
 ||| Call the RTS's file opening function
 private
@@ -95,15 +96,13 @@ export
 fopen : (f : String) -> (m : String) -> IO (Either FileError File)
 fopen f m = do h <- do_fopen f m
                if !(nullPtr h)
-                  then do err <- getFileError
-                          pure (Left err)
+                  then Left <$> getFileError
                   else pure (Right (FHandle h))
 
 ||| Check whether a file handle is actually a null pointer
 export
 validFile : File -> IO Bool
-validFile (FHandle h) = do x <- nullPtr h
-                           pure (not x)
+validFile (FHandle h) = not <$> nullPtr h
 
 ||| Modes for opening files
 data Mode = Read | WriteTruncate | Append | ReadWrite | ReadWriteTruncate | ReadAppend
@@ -169,38 +168,33 @@ fileSize : File -> IO (Either FileError Int)
 fileSize (FHandle h) 
     = do s <- do_getFileSize h
          if (s < 0)
-            then do err <- getFileError
-                    pure (Left err)
+            then Left <$> getFileError
             else pure (Right s)
 
 export
 fileModifiedTime : File -> IO (Either FileError Integer)
 fileModifiedTime (FHandle h)
     = do s <- do_getFileModifiedTime h
          if (s < 0)
-            then do err <- getFileError
-                    pure (Left err)
+            then Left <$> getFileError
             else pure (Right s)
 
 export
 fileAccessTime : File -> IO (Either FileError Integer)
 fileAccessTime (FHandle h)
     = do s <- do_getFileAccessTime h
          if (s < 0)
-            then do err <- getFileError
-                    pure (Left err)
+            then Left <$> getFileError
             else pure (Right s)
 
 export
 fileStatusTime : File -> IO (Either FileError Integer)
 fileStatusTime (FHandle h)
     = do s <- do_getFileStatusTime h
          if (s < 0)
-            then do err <- getFileError
-                    pure (Left err)
+            then Left <$> getFileError
             else pure (Right s)
 
-
 private
 do_fread : Ptr -> IO' l String
 do_fread h = prim_fread h
@@ -264,8 +258,7 @@ do_fwrite h s = do res <- prim_fwrite h s
                       then do errno <- getErrno
                               if errno == 0
                                  then pure (Left FileWriteError)
-                                 else do err <- getFileError
-                                         pure (Left err)
+                                 else Left <$> getFileError
                       else pure (Right ())
 
 ||| Write a line to a file
@@ -287,7 +280,7 @@ do_feof h = foreign FFI_C "fileEOF" (Ptr -> IO Int) h
 export
 fEOF : File -> IO Bool
 fEOF (FHandle h) = do eof <- do_feof h
-                      pure (not (eof == 0))
+                      pure (eof /= 0)
 
 private
 do_fremove : String -> IO Int
@@ -317,7 +310,8 @@ readFile : (filepath : String) -> IO (Either FileError String)
 readFile fn = do Right h <- openFile fn Read
                     | Left err => pure (Left err)
                  Right max <- fileSize h
-                    | Left err => pure (Left err)
+                    | Left err => do closeFile h
+                                     pure (Left err)
                  sb <- newStringBuffer (max + 1)
                  c <- readFile' h max sb
                  closeFile h
@@ -340,8 +334,11 @@ export
 writeFile : (filepath : String) -> (contents : String) ->
             IO (Either FileError ())
 writeFile fn contents = do
-     Right h  <- openFile fn WriteTruncate | Left err => pure (Left err)
-     Right () <- fPutStr h contents        | Left err => pure (Left err)
+     Right h  <- openFile fn WriteTruncate 
+        | Left err => pure (Left err)
+     Right () <- fPutStr h contents        
+        | Left err => do closeFile h
+                         pure (Left err)
      closeFile h
      pure (Right ())
 
@@ -351,8 +348,7 @@ dirOpen : (d : String) -> IO (Either FileError Directory)
 dirOpen d
     = do dptr <- foreign FFI_C "idris_dirOpen" (String -> IO Ptr) d
          if !(nullPtr dptr)
-            then do err <- getFileError
-                    pure (Left err)
+            then Left <$> getFileError
             else pure (Right (DHandle dptr))
 
 export
@@ -363,7 +359,7 @@ export
 dirError : Directory -> IO Bool
 dirError (DHandle d)
     = do err <- foreign FFI_C "idris_dirError" (Ptr -> IO Int) d
-         pure (not (err == 0))
+         pure (err /= 0)
 
 export
 dirEntry : Directory -> IO (Either FileError String)
@@ -379,8 +375,7 @@ createDir d
     = do ok <- foreign FFI_C "idris_mkdir" (String -> IO Int) d
          if (ok == 0)
             then pure (Right ())
-            else do err <- getFileError
-                    pure (Left err)
+            else Left <$> getFileError
 
 export
 changeDir : String -> IO Bool