assistant: Detect when system is not configured with a user name, and set environment to prevent git from failing.

Assistant/Environment.hs

@@ -0,0 +1,26 @@
+{- git-annex assistant environment
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Assistant.Environment where
+
+import Assistant.Common
+import Utility.UserInfo
+import qualified Git.Config
+
+import System.Posix.Env
+
+{- Checks that the system's environment allows git to function.
+ - Git requires a GECOS username, or suitable git configuration, or
+ - environment variables. -}
+checkEnvironment :: Annex ()
+checkEnvironment = do
+	username <- liftIO myUserName
+	gecos <- liftIO myUserGecos
+	gitusername <- fromRepo $ Git.Config.getMaybe "user.name"
+	when (null gecos && (gitusername == Nothing || gitusername == Just "")) $
+		-- existing environment is not overwritten
+		liftIO $ setEnv "GIT_AUTHOR_NAME" username False