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