git-annex/Utility/Path.hs
Joey Hess 294991dacb Significantly sped up processing of large numbers of directories passed to a single git-annex command. (try 2)
New approach is to do it the expensive way for the first 100 paths
on the command line, but then assume the user doesn't care about order too
much and fall back to the cheap way that does not preserve order.
2015-04-02 01:44:32 -04:00

313 lines
9.9 KiB
Haskell

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