propellor spin

debian/changelog

@@ -8,7 +8,8 @@ propellor (0.8.0) UNRELEASED; urgency=medium
     to store the privdata using the new storage scheme.
 
   * Add --edit to edit a privdata value in $EDITOR.
-  * Add --list-fields to list all currently set privdata fields.
+  * Add --list-fields to list all currently set privdata fields, along with
+    the hosts that use them.
   * Fix randomHostKeys property to run openssh-server's postinst in a
     non-failing way.
   * Hostname.sane now cleans up the 127.0.0.1 localhost line in /etc/hosts,

propellor.cabal

@@ -127,6 +127,7 @@ Library
     Utility.Process
     Utility.SafeCommand
     Utility.Scheduled
+    Utility.Table
     Utility.ThreadScheduler
     Utility.Tmp
     Utility.UserInfo

src/Propellor/PrivData.hs

@@ -26,6 +26,7 @@ import Utility.SafeCommand
 import Utility.Misc
 import Utility.FileMode
 import Utility.Env
+import Utility.Table
 
 -- | Allows a Property to access the value of a specific PrivDataField,
 -- for use in a specific Context.
@@ -90,10 +91,17 @@ editPrivData field context = do
 listPrivDataFields :: IO ()
 listPrivDataFields = do
 	m <- decryptPrivData
-	putStrLn ("\nAll currently set privdata fields:")
+	putStrLn "\n"
-	mapM_ list $ M.keys m
+	let rows = map mkrow (M.keys m)
+	let table = tableWithHeader header rows
+	putStr $ unlines $ formatTable table
   where
-	list = putStrLn . ("\t" ++) . shellEscape . show
+  	header = ["Field", "Context", "Hosts"]
+	mkrow (field, (Context context)) =
+		[ shellEscape $ show field
+		, shellEscape context
+		, "xxx"
+		]
 
 setPrivDataTo :: PrivDataField -> Context -> PrivData -> IO ()
 setPrivDataTo field context value = do

src/Utility/Table.hs

@@ -0,0 +1,28 @@
+{- text based table generation
+ -
+ - Copyright 2014 Joey Hess <joey@kitenet.net>
+ -
+ - License: BSD-2-clause
+ -}
+
+module Utility.Table where
+
+type Table = [[String]]
+
+-- | A table with a header that is set off with lines under each
+-- header item.
+tableWithHeader :: [String] -> [[String]] -> Table
+tableWithHeader header rows = header : map linesep header : rows
+  where
+	linesep = map (const '-')
+
+-- | Formats a table to lines, automatically padding rows to the same size.
+formatTable :: Table -> [String]
+formatTable table = map (\r -> unwords (map pad (zip r rowsizes))) table
+  where
+	pad (cell, size) = cell ++ take (size - length cell) padding
+	padding = repeat ' '
+	rowsizes = sumrows (map (map length) table)
+	sumrows [] = repeat 0
+	sumrows [r] = r
+	sumrows (r1:r2:rs) = sumrows $ map (uncurry max) (zip r1 r2) : rs