If the keys have not changed, then avoid sudo. (#16)

awakesecurity · Apr 8, 2018 · d9fe20d · d9fe20d
1 parent e8577c5
commit d9fe20d
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Showing 2 changed files with 41 additions and 28 deletions.
diff --git a/nix-deploy.cabal b/nix-deploy.cabal
@@ -31,6 +31,7 @@ executable nix-deploy
   ghc-options:         -Wall
   build-depends:
                 base                 >= 4.9.0.0  && < 5
+              , bytestring           >= 0.10.8.1 && < 1.0
               , optparse-generic     >= 1.2.0    && < 1.3
               , optparse-applicative >= 0.13.0.0 && < 0.15
               , neat-interpolation                  < 0.4

diff --git a/src/Main.hs b/src/Main.hs
@@ -22,6 +22,7 @@ import           Control.Exception      (SomeException)
 import qualified Control.Exception
 import           Control.Monad
 import           Control.Monad.IO.Class (MonadIO)
+import qualified Data.ByteString.Lazy   as BL
 import qualified Data.List.NonEmpty     as NonEmpty
 import           Data.Maybe
 import           Data.Monoid            ((<>))
@@ -259,7 +260,7 @@ main =
           Turtle.die [text|[x] Failed to switch $targetText to $pathText|]
 
       when (method == Reboot)$ do
-        let success = 
+        let success =
               stderrLines [text|[+] $pathText successfully activated, $targetText is rebooting|]
         rebootCmd targetText >>= \case
           -- This is the exit code returned by `ssh` when the machine closes
@@ -412,31 +413,42 @@ exchangeKeys host = do
 
           liftIO (Control.Exception.handle handler1 download)
 
-          exitCode <- Turtle.shell "sudo -n true 2>/dev/null" empty
-
-          -- NB: path shouldn't is a FilePath and won't have any
-          -- newlines, so this should be okay
-          Turtle.err (Turtle.unsafeTextToLine $ Turtle.format ("[+] Installing: "%fp) path)
-
-          case exitCode of
-              ExitFailure _ -> do
-                  Turtle.err ""
-                  Turtle.err "    This will prompt you for your `sudo` password"
-              _             -> do
-                  return ()
-
-          let install =
-                  Turtle.procs "sudo"
-                      [ "mv"
-                      , Turtle.format fp localPath
-                      , Turtle.format fp path
-                      ]
-                      empty
-          let handler2 :: SomeException -> IO ()
-              handler2 e = do
-                  let pathText      = Turtle.format fp path
-                  let exceptionText = Text.pack (show e)
-                  let msg           = [text|
+          new <- liftIO . BL.readFile . Text.unpack $
+            Turtle.format fp localPath
+
+          old <- liftIO . BL.readFile . Text.unpack $
+            Turtle.format fp path
+
+          if new == old
+              then do
+                  let same = Turtle.format ("[+] Unchanged: "%fp) path
+                  mapM_ Turtle.err (Turtle.Line.textToLines same)
+              else do
+                  exitCode <- Turtle.shell "sudo -n true 2>/dev/null" empty
+
+                  -- NB: path shouldn't is a FilePath and won't have any
+                  -- newlines, so this should be okay
+                  Turtle.err (Turtle.unsafeTextToLine $ Turtle.format ("[+] Installing: "%fp) path)
+
+                  case exitCode of
+                      ExitFailure _ -> do
+                          Turtle.err ""
+                          Turtle.err "    This will prompt you for your `sudo` password"
+                      _             -> do
+                          return ()
+
+                  let install =
+                          Turtle.procs "sudo"
+                              [ "mv"
+                              , Turtle.format fp localPath
+                              , Turtle.format fp path
+                              ]
+                              empty
+                  let handler2 :: SomeException -> IO ()
+                      handler2 e = do
+                          let pathText      = Turtle.format fp path
+                          let exceptionText = Text.pack (show e)
+                          let msg           = [text|
 [x] Could not install: $pathText
 
     Debugging tips:
@@ -449,9 +461,9 @@ exchangeKeys host = do
 
     Original error: $exceptionText
 |]
-                  Turtle.die msg
+                          Turtle.die msg
 
-          liftIO (Control.Exception.handle handler2 install)
+                  liftIO (Control.Exception.handle handler2 install)
 
   mirror privateKey
   mirror publicKey