From 54db9a94963826141c79ffe30df0453f85a117c8 Mon Sep 17 00:00:00 2001
From: Egor Tensin <Egor.Tensin@gmail.com>
Date: Wed, 13 Jul 2016 03:28:51 +0300
Subject: bugfix + refactoring

---
 src/Environment.hs | 15 ++++++++++-----
 src/Registry.hs    | 11 +++--------
 2 files changed, 13 insertions(+), 13 deletions(-)

(limited to 'src')

diff --git a/src/Environment.hs b/src/Environment.hs
index c0dd723..eef1948 100644
--- a/src/Environment.hs
+++ b/src/Environment.hs
@@ -19,6 +19,7 @@ module Environment
 import Control.Monad   (when)
 import Data.List       (intercalate)
 import Data.List.Split (splitOn)
+import Data.Maybe      (fromJust, isJust)
 import System.IO.Error (catchIOError, isDoesNotExistError)
 
 import qualified Graphics.Win32.Window as WinAPI
@@ -64,12 +65,12 @@ notifyEnvUpdate =
 
     allWindows = WinAPI.castUINTPtrToPtr 0xffff
 
-query :: RegistryLocation -> Registry.ValueName -> IO Registry.ValueData
+query :: RegistryLocation -> Registry.ValueName -> IO (Maybe Registry.ValueData)
 query env name = do
     keyHandle <- openRegistryKey env
-    catchIOError (Registry.getString keyHandle name) emptyIfDoesNotExist
+    catchIOError (Registry.getString keyHandle name >>= return . Just) emptyIfDoesNotExist
   where
-    emptyIfDoesNotExist e = if isDoesNotExistError e then return "" else ioError e
+    emptyIfDoesNotExist e = if isDoesNotExistError e then return Nothing else ioError e
 
 engrave :: RegistryLocation -> Registry.ValueName -> Registry.ValueData -> IO ()
 engrave env name value = do
@@ -81,8 +82,12 @@ engraveWithPrompt :: RegistryLocation -> Registry.ValueName -> Registry.ValueDat
 engraveWithPrompt env name value = do
     putStrLn $ "Saving variable '" ++ name ++ "' to '" ++ registryKeyPath env ++ "'..."
     oldValue <- query env name
-    putStrLn $ "\tOld value: " ++ oldValue
-    putStrLn $ "\tNew value: " ++ value
+    if (isJust oldValue)
+        then do
+            putStrLn $ "\tOld value: " ++ fromJust oldValue
+            putStrLn $ "\tNew value: " ++ value
+        else do
+            putStrLn $ "\tValue: " ++ value
     agreed <- Utils.promptToContinue
     when agreed $ engrave env name value
 
diff --git a/src/Registry.hs b/src/Registry.hs
index 4aac81d..4a7c593 100644
--- a/src/Registry.hs
+++ b/src/Registry.hs
@@ -83,9 +83,6 @@ exitCodeSuccess = 0
 exitCodeFileNotFound :: WinAPI.ErrCode
 exitCodeFileNotFound = 0x2
 
-exitCodeMoreData :: WinAPI.ErrCode
-exitCodeMoreData = 0xea
-
 raiseError :: String -> WinAPI.ErrCode -> IO a
 raiseError functionName ret
     | ret == exitCodeFileNotFound = raiseDoesNotExistError functionName
@@ -121,11 +118,9 @@ getString keyHandle valueName =
     alloca $ \dataSizePtr -> do
         poke dataSizePtr 0
         ret <- WinAPI.c_RegQueryValueEx keyPtr valueNamePtr WinAPI.nullPtr WinAPI.nullPtr WinAPI.nullPtr dataSizePtr
-        if ret == exitCodeSuccess
-            then return ""
-            else if ret /= exitCodeMoreData
-                then raiseError "RegQueryValueEx" ret
-                else getStringTerminated keyPtr valueNamePtr dataSizePtr
+        if ret /= exitCodeSuccess
+            then raiseError "RegQueryValueEx" ret
+            else getStringTerminated keyPtr valueNamePtr dataSizePtr
   where
     getStringTerminated keyPtr valueNamePtr dataSizePtr = do
         dataSize <- peek dataSizePtr
-- 
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