git-annex/Utility/Path.hs
Joey Hess 3a05d53761
add SeekInput (not yet used)
No behavior changes (hopefully), just adding SeekInput and plumbing it
through to the JSON display code for later use.

Over the course of 2 grueling days.

withFilesNotInGit reimplemented in terms of seekHelper
should be the only possible behavior change. It seems to test as
behaving the same.

Note that seekHelper dummies up the SeekInput in the case where
segmentPaths' gives up on sorting the expanded paths because there are
too many input paths. When SeekInput later gets exposed as a json field,
that will result in it being a little bit wrong in the case where
100 or more paths are passed to a git-annex command. I think this is a
subtle enough problem to not matter. If it does turn out to be a
problem, fixing it would require splitting up the input
parameters into groups of < 100, which would make git ls-files run
perhaps more than is necessary. May want to revisit this, because that
fix seems fairly low-impact.
2020-09-15 15:41:13 -04:00

303 lines
9.5 KiB
Haskell

{- path manipulation
-
- Copyright 2010-2020 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE CPP #-}
{-# OPTIONS_GHC -fno-warn-tabs #-}
module Utility.Path (
simplifyPath,
absPathFrom,
parentDir,
upFrom,
dirContains,
absPath,
relPathCwdToFile,
relPathDirToFile,
relPathDirToFileAbs,
segmentPaths,
segmentPaths',
runSegmentPaths,
runSegmentPaths',
relHome,
inPath,
searchPath,
dotfile,
splitShortExtensions,
prop_upFrom_basics,
prop_relPathDirToFile_basics,
prop_relPathDirToFile_regressionTest,
) where
import System.FilePath
import Data.List
import Data.Maybe
#ifdef mingw32_HOST_OS
import Data.Char
#endif
import Control.Applicative
import Prelude
import Utility.Monad
import Utility.UserInfo
import Utility.SystemDirectory
import Utility.Split
import Utility.FileSystemEncoding
{- Simplifies a path, removing any "." component, collapsing "dir/..",
- 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' == ".." && not (null c) && dropTrailingPathSeparator (c !! 0) /= ".." =
norm (drop 1 c) ps
| p' == "." = norm c ps
| otherwise = norm (p:c) ps
where
p' = dropTrailingPathSeparator p
{- Makes a path absolute.
-
- Also simplifies it using simplifyPath.
-
- The first parameter is a base directory (ie, the cwd) to use if the path
- is not already absolute, and should itsef be 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)
{- 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 "." or "foo") -}
upFrom :: FilePath -> Maybe FilePath
upFrom dir
| length dirs < 2 = Nothing
| otherwise = Just $ joinDrive drive $ intercalate s $ init dirs
where
-- on Unix, the drive will be "/" when the dir is absolute,
-- otherwise ""
(drive, path) = splitDrive dir
s = [pathSeparator]
dirs = filter (not . null) $ split s path
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'
|| a' == "." && normalise ("." </> b') == b'
where
a' = norm a
b' = norm b
norm = normalise . simplifyPath
{- Converts a filename into an absolute path.
-
- Also simplifies it using simplifyPath.
-
- Unlike Directory.canonicalizePath, this does not require the path
- already exists. -}
absPath :: FilePath -> IO FilePath
absPath file
-- Avoid unncessarily getting the current directory when the path
-- is already absolute. absPathFrom uses simplifyPath
-- so also used here for consistency.
| isAbsolute file = return $ simplifyPath file
| otherwise = 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 ./
-
- On Windows, if the paths are on different drives,
- a relative path is not possible and the path is simply
- returned as-is.
-}
relPathDirToFileAbs :: FilePath -> FilePath -> FilePath
relPathDirToFileAbs from to
#ifdef mingw32_HOST_OS
| normdrive from /= normdrive to = to
#endif
| otherwise = joinPath $ dotdots ++ uncommon
where
pfrom = sp from
pto = sp to
sp = map dropTrailingPathSeparator . splitPath . dropDrive
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
#ifdef mingw32_HOST_OS
normdrive = map toLower . takeWhile (/= ':') . takeDrive
#endif
prop_relPathDirToFile_basics :: FilePath -> FilePath -> Bool
prop_relPathDirToFile_basics from to
| null from || null to = True
| 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 :: (a -> RawFilePath) -> [RawFilePath] -> [a] -> [[a]]
segmentPaths = segmentPaths' (\_ r -> r)
segmentPaths' :: (Maybe RawFilePath -> a -> r) -> (a -> RawFilePath) -> [RawFilePath] -> [a] -> [[r]]
segmentPaths' f _ [] new = [map (f Nothing) new]
segmentPaths' f _ [i] new = [map (f (Just i)) new] -- optimisation
segmentPaths' f c (i:is) new =
map (f (Just i)) found : segmentPaths' f c is rest
where
(found, rest) = if length is < 100
then partition ini new
else break (not . ini) new
ini f = i' `dirContains` fromRawFilePath (c f)
i' = fromRawFilePath i
{- 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 :: (a -> RawFilePath) -> ([RawFilePath] -> IO [a]) -> [RawFilePath] -> IO [[a]]
runSegmentPaths c a paths = segmentPaths c paths <$> a paths
runSegmentPaths' :: (Maybe RawFilePath -> a -> r) -> (a -> RawFilePath) -> ([RawFilePath] -> IO [a]) -> [RawFilePath] -> IO [[r]]
runSegmentPaths' si c a paths = segmentPaths' si c paths <$> 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.
-
- Note that this will find commands in PATH that are not executable.
-}
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
{- 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