git-annex/Utility/Path/AbsRel.hs
2023-10-26 14:00:02 -04:00

86 lines
2.5 KiB
Haskell

{- absolute and relative path manipulation
-
- Copyright 2010-2021 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE OverloadedStrings #-}
{-# OPTIONS_GHC -fno-warn-tabs #-}
module Utility.Path.AbsRel (
absPathFrom,
absPath,
relPathCwdToFile,
relPathDirToFile,
relPathDirToFileAbs,
relHome,
) where
import System.FilePath.ByteString
import qualified Data.ByteString as B
import Control.Applicative
import Prelude
import Utility.Path
import Utility.UserInfo
import Utility.FileSystemEncoding
import qualified Utility.RawFilePath as R
{- 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 itself be absolute.
-
- Does not attempt to deal with edge cases or ensure security with
- untrusted inputs.
-}
absPathFrom :: RawFilePath -> RawFilePath -> RawFilePath
absPathFrom dir path = simplifyPath (combine dir path)
{- Converts a filename into an absolute path.
-
- Also simplifies it using simplifyPath.
-
- Unlike Directory.canonicalizePath, this does not require the path
- already exists. -}
absPath :: RawFilePath -> IO RawFilePath
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 <- R.getCurrentDirectory
return $ absPathFrom cwd file
{- Constructs the minimal relative path from the CWD to a file.
-
- For example, assuming CWD is /tmp/foo/bar:
- relPathCwdToFile "/tmp/foo" == ".."
- relPathCwdToFile "/tmp/foo/bar" == ""
- relPathCwdToFile "../bar/baz" == "baz"
-}
relPathCwdToFile :: RawFilePath -> IO RawFilePath
relPathCwdToFile f
-- Optimisation: Avoid doing any IO when the path is relative
-- and does not contain any ".." component.
| isRelative f && not (".." `B.isInfixOf` f) = return f
| otherwise = do
c <- R.getCurrentDirectory
relPathDirToFile c f
{- Constructs a minimal relative path from a directory to a file. -}
relPathDirToFile :: RawFilePath -> RawFilePath -> IO RawFilePath
relPathDirToFile from to = relPathDirToFileAbs <$> absPath from <*> absPath to
{- Converts paths in the home directory to use ~/ -}
relHome :: FilePath -> IO String
relHome path = do
let path' = toRawFilePath path
home <- toRawFilePath <$> myHomeDir
return $ if dirContains home path'
then fromRawFilePath ("~/" <> relPathDirToFileAbs home path')
else path