Make propellor resistent to changes to shared libraries, such as libffi

* Make propellor resistent to changes to shared libraries, such as libffi,
  which might render the propellor binary unable to run. This is dealt with
  by checking the binary both when running propellor on a remote host,
  and by Cron.runPropellor. If the binary doesn't work, it will be rebuilt.
* Note that since a new switch had to be added to allow testing the binary,
  upgrading to this version will cause a rebuild from scratch of propellor.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/Propellor/CmdLine.hs b/src/Propellor/CmdLine.hs
index 9d7d0d95..1298daf2 100644
--- a/src/Propellor/CmdLine.hs
+++ b/src/Propellor/CmdLine.hs
@@ -33,6 +33,7 @@ usage h = hPutStrLn h $ unlines
 	, "  propellor --list-fields"
 	, "  propellor --merge"
 	, "  propellor --build"
+	, "  propellor --check"
 	]
 
 usageError :: [String] -> IO a
@@ -43,6 +44,7 @@ usageError ps = do
 processCmdLine :: IO CmdLine
 processCmdLine = go =<< getArgs
   where
+  	go ("--check":_) = return Check
 	go ("--spin":ps) = case reverse ps of
 		(r:"--via":hs) -> Spin 
 			<$> mapM hostname (reverse hs) 
@@ -91,6 +93,7 @@ defaultMain hostlist = do
   where
 	go _ (Serialized cmdline) = go True cmdline
 	go _ (Continue cmdline) = go False cmdline
+	go _ Check = return ()
 	go _ (Set field context) = setPrivData field context
 	go _ (Dump field context) = dumpPrivData field context
 	go _ (Edit field context) = editPrivData field context