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-rw-r--r--CGroup/Types.hs51
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+-- |
+-- Module: CGroup.Types
+-- Copyright: (c) 2014 Tomislav Viljetić
+-- License: BSD3
+-- Maintainer: Tomislav Viljetić <tomislav@viljetic.de>
+--
+
+module CGroup.Types
+ ( CGroup
+ , cgroup
+ , cgroupPath
+ , ProcessID
+ ) where
+
+import Data.Monoid
+import qualified System.FilePath as FP
+
+
+-- | A 'CGroup' is defined by a mount point and a cgroup name.
+--
+-- The mount point specifies where the cgroup hierarchy is mounted.
+-- The cgroup name is a 'FilePath' relative to the mount point.
+data CGroup = CGroup { mountPoint, cgroupName :: FilePath }
+ deriving Show
+
+
+-- | @'cgroup' mountPoint cgroupName@ is a smart constructor for 'CGroup'.
+--
+-- It will return 'Nothing' if @cgroupName@ could point outside
+-- @mountPoint@ in order to prevent directory traversal attacks.
+cgroup :: FilePath -> FilePath -> Maybe CGroup
+cgroup mp0 cgn0
+ | ".." `elem` parts = Nothing
+ | FP.isAbsolute cgn = Nothing
+ | otherwise = Just CGroup { mountPoint = mp, cgroupName = cgn }
+ where
+ mp = normaliseMountPoint mp0
+ cgn = normaliseCGroupName cgn0
+ parts = FP.splitDirectories cgn
+ normaliseMountPoint = FP.addTrailingPathSeparator . FP.normalise
+ normaliseCGroupName = FP.dropTrailingPathSeparator . FP.normalise
+
+
+-- | @'cgroupPath' g@ returns the absolute 'FilePath' of cgroup @g@.
+cgroupPath :: CGroup -> FilePath
+cgroupPath CGroup { mountPoint = mp, cgroupName = cgn } =
+ mp <> cgn
+
+
+-- | A 'ProcessID' defines a task / process.
+type ProcessID = Int