323 lines
10 KiB
Haskell
323 lines
10 KiB
Haskell
{- path manipulation
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-
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- Copyright 2010-2014 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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{-# LANGUAGE PackageImports, CPP #-}
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{-# OPTIONS_GHC -fno-warn-tabs #-}
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module Utility.Path where
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import System.FilePath
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import Data.List
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import Data.Maybe
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import Data.Char
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import Control.Applicative
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import Prelude
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#ifdef mingw32_HOST_OS
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import qualified System.FilePath.Posix as Posix
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#else
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import System.Posix.Files
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import Utility.Exception
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#endif
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import Utility.Monad
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import Utility.UserInfo
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import Utility.Directory
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import Utility.Split
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{- Simplifies a path, removing any "." component, collapsing "dir/..",
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- and removing the trailing path separator.
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-
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- On Windows, preserves whichever style of path separator might be used in
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- the input FilePaths. This is done because some programs in Windows
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- demand a particular path separator -- and which one actually varies!
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-
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- This does not guarantee that two paths that refer to the same location,
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- and are both relative to the same location (or both absolute) will
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- yeild the same result. Run both through normalise from System.FilePath
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- to ensure that.
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-}
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simplifyPath :: FilePath -> FilePath
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simplifyPath path = dropTrailingPathSeparator $
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joinDrive drive $ joinPath $ norm [] $ splitPath path'
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where
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(drive, path') = splitDrive path
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norm c [] = reverse c
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norm c (p:ps)
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| p' == ".." && not (null c) && dropTrailingPathSeparator (c !! 0) /= ".." =
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norm (drop 1 c) ps
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| p' == "." = norm c ps
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| otherwise = norm (p:c) ps
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where
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p' = dropTrailingPathSeparator p
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{- Makes a path absolute.
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-
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- The first parameter is a base directory (ie, the cwd) to use if the path
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- is not already absolute, and should itsef be absolute.
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-
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- Does not attempt to deal with edge cases or ensure security with
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- untrusted inputs.
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-}
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absPathFrom :: FilePath -> FilePath -> FilePath
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absPathFrom dir path = simplifyPath (combine dir path)
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{- takeDirectory "foo/bar/" is "foo/bar". This instead yields "foo" -}
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parentDir :: FilePath -> FilePath
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parentDir = takeDirectory . dropTrailingPathSeparator
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{- Just the parent directory of a path, or Nothing if the path has no
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- parent (ie for "/" or ".") -}
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upFrom :: FilePath -> Maybe FilePath
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upFrom dir
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| length dirs < 2 = Nothing
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| otherwise = Just $ joinDrive drive $ intercalate s $ init dirs
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where
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-- on Unix, the drive will be "/" when the dir is absolute,
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-- otherwise ""
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(drive, path) = splitDrive dir
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s = [pathSeparator]
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dirs = filter (not . null) $ split s path
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prop_upFrom_basics :: FilePath -> Bool
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prop_upFrom_basics dir
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| null dir = True
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| dir == "/" = p == Nothing
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| otherwise = p /= Just dir
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where
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p = upFrom dir
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{- Checks if the first FilePath is, or could be said to contain the second.
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- For example, "foo/" contains "foo/bar". Also, "foo", "./foo", "foo/" etc
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- are all equivilant.
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-}
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dirContains :: FilePath -> FilePath -> Bool
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dirContains a b = a == b || a' == b' || (addTrailingPathSeparator a') `isPrefixOf` b'
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where
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a' = norm a
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b' = norm b
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norm = normalise . simplifyPath
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{- Converts a filename into an absolute path.
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-
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- Unlike Directory.canonicalizePath, this does not require the path
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- already exists. -}
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absPath :: FilePath -> IO FilePath
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absPath file = do
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cwd <- getCurrentDirectory
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return $ absPathFrom cwd file
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{- Constructs a relative path from the CWD to a file.
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-
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- For example, assuming CWD is /tmp/foo/bar:
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- relPathCwdToFile "/tmp/foo" == ".."
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- relPathCwdToFile "/tmp/foo/bar" == ""
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-}
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relPathCwdToFile :: FilePath -> IO FilePath
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relPathCwdToFile f = do
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c <- getCurrentDirectory
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relPathDirToFile c f
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{- Constructs a relative path from a directory to a file. -}
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relPathDirToFile :: FilePath -> FilePath -> IO FilePath
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relPathDirToFile from to = relPathDirToFileAbs <$> absPath from <*> absPath to
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{- This requires the first path to be absolute, and the
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- second path cannot contain ../ or ./
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-
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- On Windows, if the paths are on different drives,
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- a relative path is not possible and the path is simply
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- returned as-is.
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-}
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relPathDirToFileAbs :: FilePath -> FilePath -> FilePath
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relPathDirToFileAbs from to
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#ifdef mingw32_HOST_OS
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| normdrive from /= normdrive to = to
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#endif
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| otherwise = joinPath $ dotdots ++ uncommon
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where
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pfrom = sp from
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pto = sp to
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sp = map dropTrailingPathSeparator . splitPath . dropDrive
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common = map fst $ takeWhile same $ zip pfrom pto
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same (c,d) = c == d
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uncommon = drop numcommon pto
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dotdots = replicate (length pfrom - numcommon) ".."
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numcommon = length common
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#ifdef mingw32_HOST_OS
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normdrive = map toLower . takeWhile (/= ':') . takeDrive
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#endif
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prop_relPathDirToFile_basics :: FilePath -> FilePath -> Bool
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prop_relPathDirToFile_basics from to
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| null from || null to = True
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| from == to = null r
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| otherwise = not (null r)
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where
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r = relPathDirToFileAbs from to
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prop_relPathDirToFile_regressionTest :: Bool
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prop_relPathDirToFile_regressionTest = same_dir_shortcurcuits_at_difference
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where
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{- Two paths have the same directory component at the same
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- location, but it's not really the same directory.
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- Code used to get this wrong. -}
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same_dir_shortcurcuits_at_difference =
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relPathDirToFileAbs (joinPath [pathSeparator : "tmp", "r", "lll", "xxx", "yyy", "18"])
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(joinPath [pathSeparator : "tmp", "r", ".git", "annex", "objects", "18", "gk", "SHA256-foo", "SHA256-foo"])
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== joinPath ["..", "..", "..", "..", ".git", "annex", "objects", "18", "gk", "SHA256-foo", "SHA256-foo"]
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{- Given an original list of paths, and an expanded list derived from it,
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- which may be arbitrarily reordered, generates a list of lists, where
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- each sublist corresponds to one of the original paths.
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-
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- When the original path is a directory, any items in the expanded list
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- that are contained in that directory will appear in its segment.
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-
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- The order of the original list of paths is attempted to be preserved in
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- the order of the returned segments. However, doing so has a O^NM
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- growth factor. So, if the original list has more than 100 paths on it,
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- we stop preserving ordering at that point. Presumably a user passing
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- that many paths in doesn't care too much about order of the later ones.
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-}
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segmentPaths :: [FilePath] -> [FilePath] -> [[FilePath]]
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segmentPaths [] new = [new]
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segmentPaths [_] new = [new] -- optimisation
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segmentPaths (l:ls) new = found : segmentPaths ls rest
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where
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(found, rest) = if length ls < 100
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then partition (l `dirContains`) new
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else break (\p -> not (l `dirContains` p)) new
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{- This assumes that it's cheaper to call segmentPaths on the result,
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- than it would be to run the action separately with each path. In
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- the case of git file list commands, that assumption tends to hold.
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-}
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runSegmentPaths :: ([FilePath] -> IO [FilePath]) -> [FilePath] -> IO [[FilePath]]
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runSegmentPaths a paths = segmentPaths paths <$> a paths
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{- Converts paths in the home directory to use ~/ -}
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relHome :: FilePath -> IO String
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relHome path = do
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home <- myHomeDir
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return $ if dirContains home path
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then "~/" ++ relPathDirToFileAbs home path
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else path
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{- Checks if a command is available in PATH.
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-
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- The command may be fully-qualified, in which case, this succeeds as
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- long as it exists. -}
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inPath :: String -> IO Bool
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inPath command = isJust <$> searchPath command
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{- Finds a command in PATH and returns the full path to it.
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-
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- The command may be fully qualified already, in which case it will
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- be returned if it exists.
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-
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- Note that this will find commands in PATH that are not executable.
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-}
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searchPath :: String -> IO (Maybe FilePath)
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searchPath command
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| isAbsolute command = check command
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| otherwise = getSearchPath >>= getM indir
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where
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indir d = check $ d </> command
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check f = firstM doesFileExist
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#ifdef mingw32_HOST_OS
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[f, f ++ ".exe"]
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#else
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[f]
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#endif
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{- Checks if a filename is a unix dotfile. All files inside dotdirs
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- count as dotfiles. -}
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dotfile :: FilePath -> Bool
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dotfile file
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| f == "." = False
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| f == ".." = False
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| f == "" = False
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| otherwise = "." `isPrefixOf` f || dotfile (takeDirectory file)
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where
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f = takeFileName file
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{- Converts a DOS style path to a msys2 style path. Only on Windows.
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- Any trailing '\' is preserved as a trailing '/'
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-
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- Taken from: http://sourceforge.net/p/msys2/wiki/MSYS2%20introduction/i
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-
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- The virtual filesystem contains:
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- /c, /d, ... mount points for Windows drives
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-}
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toMSYS2Path :: FilePath -> FilePath
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#ifndef mingw32_HOST_OS
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toMSYS2Path = id
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#else
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toMSYS2Path p
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| null drive = recombine parts
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| otherwise = recombine $ "/" : driveletter drive : parts
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where
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(drive, p') = splitDrive p
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parts = splitDirectories p'
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driveletter = map toLower . takeWhile (/= ':')
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recombine = fixtrailing . Posix.joinPath
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fixtrailing s
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| hasTrailingPathSeparator p = Posix.addTrailingPathSeparator s
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| otherwise = s
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#endif
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{- Maximum size to use for a file in a specified directory.
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-
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- Many systems have a 255 byte limit to the name of a file,
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- so that's taken as the max if the system has a larger limit, or has no
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- limit.
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-}
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fileNameLengthLimit :: FilePath -> IO Int
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#ifdef mingw32_HOST_OS
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fileNameLengthLimit _ = return 255
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#else
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fileNameLengthLimit dir = do
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-- getPathVar can fail due to statfs(2) overflow
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l <- catchDefaultIO 0 $
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fromIntegral <$> getPathVar dir FileNameLimit
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if l <= 0
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then return 255
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else return $ minimum [l, 255]
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#endif
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{- Given a string that we'd like to use as the basis for FilePath, but that
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- was provided by a third party and is not to be trusted, returns the closest
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- sane FilePath.
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-
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- All spaces and punctuation and other wacky stuff are replaced
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- with '_', except for '.'
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- "../" will thus turn into ".._", which is safe.
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-}
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sanitizeFilePath :: String -> FilePath
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sanitizeFilePath = map sanitize
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where
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sanitize c
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| c == '.' = c
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| isSpace c || isPunctuation c || isSymbol c || isControl c || c == '/' = '_'
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| otherwise = c
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{- Similar to splitExtensions, but knows that some things in FilePaths
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- after a dot are too long to be extensions. -}
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splitShortExtensions :: FilePath -> (FilePath, [String])
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splitShortExtensions = splitShortExtensions' 5 -- enough for ".jpeg"
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splitShortExtensions' :: Int -> FilePath -> (FilePath, [String])
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splitShortExtensions' maxextension = go []
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where
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go c f
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| len > 0 && len <= maxextension && not (null base) =
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go (ext:c) base
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| otherwise = (f, c)
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where
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(base, ext) = splitExtension f
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len = length ext
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