Set GPG_TTY when run at a terminal

so that gpg can do password prompting despite being connected by pipes to
propellor (or git).

2 files changed, 22 insertions, 0 deletions

diff --git a/src/Propellor/CmdLine.hs b/src/Propellor/CmdLine.hs
index cba5991d..bd01b34c 100644
--- a/src/Propellor/CmdLine.hs
+++ b/src/Propellor/CmdLine.hs
@@ -111,6 +111,7 @@ data CanRebuild = CanRebuild | NoRebuild
 defaultMain :: [Host] -> IO ()
 defaultMain hostlist = withConcurrentOutput $ do
 	useFileSystemEncoding
+	setupGpgEnv
 	Shim.cleanEnv
 	checkDebugMode
 	cmdline <- processCmdLine
diff --git a/src/Propellor/Gpg.hs b/src/Propellor/Gpg.hs
index 43c4eddf..5df16389 100644
--- a/src/Propellor/Gpg.hs
+++ b/src/Propellor/Gpg.hs
@@ -1,6 +1,8 @@
 module Propellor.Gpg where
 
 import System.IO
+import System.Posix.IO
+import System.Posix.Terminal
 import Data.Maybe
 import Control.Monad
 import Control.Applicative
@@ -19,6 +21,25 @@ import Utility.Env
 import Utility.Directory
 import Utility.Split
 
+-- | When at a tty, set GPG_TTY to point to the tty device. This is needed
+-- so that when gpg is run with stio connected to a pipe, it is still able
+-- to display password prompts at the console.
+--
+-- This should not prevent gpg from using the GUI for prompting when one is
+-- available.
+setupGpgEnv :: IO ()
+setupGpgEnv = checkhandles [stdInput, stdOutput, stdError]
+  where
+	checkhandles [] = return ()
+	checkhandles (h:hs) = do
+		isterm <- queryTerminal h
+		if isterm
+			then do
+				ttyname <- getTerminalName h
+				-- do not overwrite
+				setEnv "GPG_TTY" ttyname False
+			else checkhandles hs
+
 type KeyId = String
 
 getGpgBin :: IO String