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|
{- safely running shell commands
-
- Copyright 2010-2015 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# OPTIONS_GHC -fno-warn-tabs #-}
module Utility.SafeCommand (
CommandParam(..),
toCommand,
boolSystem,
boolSystem',
boolSystemEnv,
safeSystem,
safeSystem',
safeSystemEnv,
segmentXargsOrdered,
segmentXargsUnordered,
) where
import Utility.Process
import System.Exit
import System.FilePath
import Data.Char
import Data.List
import Control.Applicative
import Prelude
-- | Parameters that can be passed to a shell command.
data CommandParam
= Param String -- ^ A parameter
| File FilePath -- ^ The name of a file
deriving (Eq, Show, Ord)
-- | Used to pass a list of CommandParams to a function that runs
-- a command and expects Strings. -}
toCommand :: [CommandParam] -> [String]
toCommand = map toCommand'
toCommand' :: CommandParam -> String
toCommand' (Param s) = s
-- Files that start with a non-alphanumeric that is not a path
-- separator are modified to avoid the command interpreting them as
-- options or other special constructs.
toCommand' (File s@(h:_))
| isAlphaNum h || h `elem` pathseps = s
| otherwise = "./" ++ s
where
-- '/' is explicitly included because it's an alternative
-- path separator on Windows.
pathseps = pathSeparator:"./"
toCommand' (File s) = s
-- | Run a system command, and returns True or False if it succeeded or failed.
--
-- (Throws an exception if the command is not found.)
--
-- This and other command running functions in this module log the commands
-- run at debug level, using System.Log.Logger.
boolSystem :: FilePath -> [CommandParam] -> IO Bool
boolSystem command params = boolSystem' command params id
boolSystem' :: FilePath -> [CommandParam] -> (CreateProcess -> CreateProcess) -> IO Bool
boolSystem' command params mkprocess = dispatch <$> safeSystem' command params mkprocess
where
dispatch ExitSuccess = True
dispatch _ = False
boolSystemEnv :: FilePath -> [CommandParam] -> Maybe [(String, String)] -> IO Bool
boolSystemEnv command params environ = boolSystem' command params $
\p -> p { env = environ }
-- | Runs a system command, returning the exit status.
safeSystem :: FilePath -> [CommandParam] -> IO ExitCode
safeSystem command params = safeSystem' command params id
safeSystem' :: FilePath -> [CommandParam] -> (CreateProcess -> CreateProcess) -> IO ExitCode
safeSystem' command params mkprocess =
withCreateProcess p $ \_ _ _ pid ->
waitForProcess pid
where
p = mkprocess $ proc command (toCommand params)
safeSystemEnv :: FilePath -> [CommandParam] -> Maybe [(String, String)] -> IO ExitCode
safeSystemEnv command params environ = safeSystem' command params $
\p -> p { env = environ }
-- | Segments a list of filenames into groups that are all below the maximum
-- command-line length limit.
segmentXargsOrdered :: [FilePath] -> [[FilePath]]
segmentXargsOrdered = reverse . map reverse . segmentXargsUnordered
-- | Not preserving order is a little faster, and streams better when
-- there are a great many filenames.
segmentXargsUnordered :: [FilePath] -> [[FilePath]]
segmentXargsUnordered l = go l [] 0 []
where
go [] c _ r = (c:r)
go (f:fs) c accumlen r
| newlen > maxlen && len < maxlen = go (f:fs) [] 0 (c:r)
| otherwise = go fs (f:c) newlen r
where
len = length f
newlen = accumlen + len
{- 10k of filenames per command, well under 100k limit
- of Linux (and OSX has a similar limit);
- allows room for other parameters etc. Also allows for
- eg, multibyte characters. -}
maxlen = 10240
|
