propellor/src/Propellor/Shim.hs

80 lines
2.5 KiB
Haskell

-- | Support for running propellor, as built outside a container,
-- inside the container, without needing to install anything into the
-- container.
--
-- Note: This is currently Debian specific, due to glibcLibs.
module Propellor.Shim (setup, cleanEnv, file) where
import Propellor
import Utility.LinuxMkLibs
import Utility.SafeCommand
import Utility.Path
import Utility.FileMode
import Utility.FileSystemEncoding
import Data.List
import System.Posix.Files
-- | Sets up a shimmed version of the program, in a directory, and
-- returns its path.
--
-- Propellor may be running from an existing shim, in which case it's
-- simply reused.
setup :: FilePath -> Maybe FilePath -> FilePath -> IO FilePath
setup propellorbin propellorbinpath dest = checkAlreadyShimmed propellorbin $ do
createDirectoryIfMissing True dest
libs <- parseLdd <$> readProcess "ldd" [propellorbin]
glibclibs <- glibcLibs
let libs' = nub $ libs ++ glibclibs
libdirs <- map (dest ++) . nub . catMaybes
<$> mapM (installLib installFile dest) libs'
let linker = (dest ++) $
fromMaybe (error "cannot find ld-linux linker") $
headMaybe $ filter ("ld-linux" `isInfixOf`) libs'
let gconvdir = (dest ++) $ parentDir $
fromMaybe (error "cannot find gconv directory") $
headMaybe $ filter ("/gconv/" `isInfixOf`) glibclibs
let linkerparams = ["--library-path", intercalate ":" libdirs ]
let shim = file propellorbin dest
writeFile shim $ unlines
[ shebang
, "GCONV_PATH=" ++ shellEscape gconvdir
, "export GCONV_PATH"
, "exec " ++ unwords (map shellEscape $ linker : linkerparams) ++
" " ++ shellEscape (fromMaybe propellorbin propellorbinpath) ++ " \"$@\""
]
modifyFileMode shim (addModes executeModes)
return shim
shebang :: String
shebang = "#!/bin/sh"
checkAlreadyShimmed :: FilePath -> IO FilePath -> IO FilePath
checkAlreadyShimmed f nope = withFile f ReadMode $ \h -> do
fileEncoding h
s <- hGetLine h
if s == shebang
then return f
else nope
-- Called when the shimmed propellor is running, so that commands it runs
-- don't see it.
cleanEnv :: IO ()
cleanEnv = void $ unsetEnv "GCONV_PATH"
file :: FilePath -> FilePath -> FilePath
file propellorbin dest = dest </> takeFileName propellorbin
installFile :: FilePath -> FilePath -> IO ()
installFile top f = do
createDirectoryIfMissing True destdir
nukeFile dest
createLink f dest `catchIO` (const copy)
where
copy = void $ boolSystem "cp" [Param "-a", Param f, Param dest]
destdir = inTop top $ parentDir f
dest = inTop top f