diff options
Diffstat (limited to 'src/Propellor/Property/File.hs')
| -rw-r--r-- | src/Propellor/Property/File.hs | 52 |
1 files changed, 49 insertions, 3 deletions
diff --git a/src/Propellor/Property/File.hs b/src/Propellor/Property/File.hs index b491ccbe..12a3e80a 100644 --- a/src/Propellor/Property/File.hs +++ b/src/Propellor/Property/File.hs @@ -82,12 +82,11 @@ fileProperty' writer desc a f = property desc $ go =<< liftIO (doesFileExist f) let new = unlines (a (lines old)) if old == new then noChange - else makeChange $ viaTmp updatefile f new + else makeChange $ updatefile new `viaStableTmp` f go False = makeChange $ writer f (unlines $ a []) - -- viaTmp makes the temp file mode 600. -- Replicate the original file's owner and mode. - updatefile f' content = do + updatefile content f' = do writer f' content s <- getFileStatus f setFileMode f' (fileMode s) @@ -98,6 +97,29 @@ dirExists :: FilePath -> Property NoInfo dirExists d = check (not <$> doesDirectoryExist d) $ property (d ++ " exists") $ makeChange $ createDirectoryIfMissing True d +-- | Creates or atomically updates a symbolic link. Does not overwrite regular +-- files or directories. +isSymlinkedTo :: FilePath -> FilePath -> Property NoInfo +link `isSymlinkedTo` target = property desc $ + go =<< (liftIO $ tryIO $ getSymbolicLinkStatus link) + where + desc = link ++ " is symlinked to " ++ target + go (Right stat) = + if isSymbolicLink stat + then checkLink + else nonSymlinkExists + go (Left _) = makeChange $ createSymbolicLink target link + + nonSymlinkExists = do + warningMessage $ link ++ " exists and is not a symlink" + return FailedChange + checkLink = do + target' <- liftIO $ readSymbolicLink link + if target == target' + then noChange + else makeChange updateLink + updateLink = createSymbolicLink target `viaStableTmp` link + -- | Ensures that a file/dir has the specified owner and group. ownerGroup :: FilePath -> User -> Group -> Property NoInfo ownerGroup f (User owner) (Group group) = property (f ++ " owner " ++ og) $ do @@ -113,3 +135,27 @@ mode :: FilePath -> FileMode -> Property NoInfo mode f v = property (f ++ " mode " ++ show v) $ do liftIO $ modifyFileMode f (const v) noChange + +-- | A temp file to use when writing new content for a file. +-- +-- This is a stable name so it can be removed idempotently. +-- +-- It ends with "~" so that programs that read many config files from a +-- directory will treat it as an editor backup file, and not read it. +stableTmpFor :: FilePath -> FilePath +stableTmpFor f = f ++ ".propellor-new~" + +-- | Creates/updates a file atomically, running the action to create the +-- stable tmp file, and then renaming it into place. +viaStableTmp :: (MonadMask m, MonadIO m) => (FilePath -> m ()) -> FilePath -> m () +viaStableTmp a f = bracketIO setup cleanup go + where + setup = do + createDirectoryIfMissing True (takeDirectory f) + let tmpfile = stableTmpFor f + nukeFile tmpfile + return tmpfile + cleanup tmpfile = tryIO $ removeFile tmpfile + go tmpfile = do + a tmpfile + liftIO $ rename tmpfile f |