content: {-# LANGUAGE CPP, ForeignFunctionInterface #-}
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  Distribution.Simple.Utils
  -- Copyright   :  Isaac Jones, Simon Marlow 2003-2004
  --                portions Copyright (c) 2007, Galois Inc.
  --
  -- Maintainer  :  cabal-devel@haskell.org
  -- Portability :  portable
  --
  -- A large and somewhat miscellaneous collection of utility functions used
  -- throughout the rest of the Cabal lib and in other tools that use the Cabal
  -- lib like @cabal-install@. It has a very simple set of logging actions. It
  -- has low level functions for running programs, a bunch of wrappers for
  -- various directory and file functions that do extra logging.
  
  {- All rights reserved.
  
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are
  met:
  
      * Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.
  
      * Redistributions in binary form must reproduce the above
        copyright notice, this list of conditions and the following
        disclaimer in the documentation and/or other materials provided
        with the distribution.
  
      * Neither the name of Isaac Jones nor the names of other
        contributors may be used to endorse or promote products derived
        from this software without specific prior written permission.
  
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -}
  
  module Distribution.Simple.Utils (
          -- * logging and errors
          die,
          dieWithLocation,
          topHandler,
          warn, notice, info, debug,
          debugNoWrap, chattyTry,
  
          -- * running programs
          rawSystemExit,
          rawSystemExitCode,
          rawSystemExitWithEnv,
          rawSystemStdout,
          rawSystemStdInOut,
          rawSystemIOWithEnv,
          maybeExit,
          xargs,
          findProgramLocation,
  
          -- * copying files
          createDirectoryIfMissingVerbose,
          copyFileVerbose,
          copyDirectoryRecursiveVerbose,
          copyFiles,
  
          -- * installing files
          installOrdinaryFile,
          installExecutableFile,
          installOrdinaryFiles,
          installDirectoryContents,
  
          -- * File permissions
          setFileOrdinary,
          setFileExecutable,
  
          -- * file names
          currentDir,
  
          -- * finding files
          findFile,
          findFirstFile,
          findFileWithExtension,
          findFileWithExtension',
  
          -- * environment variables
          isInSearchPath,
  
          -- * simple file globbing
          matchFileGlob,
          matchDirFileGlob,
          parseFileGlob,
          FileGlob(..),
  
          -- * temp files and dirs
          withTempFile,
          withTempDirectory,
  
          -- * .cabal and .buildinfo files
          defaultPackageDesc,
          findPackageDesc,
          defaultHookedPackageDesc,
          findHookedPackageDesc,
  
          -- * reading and writing files safely
          withFileContents,
          writeFileAtomic,
          rewriteFile,
  
          -- * Unicode
          fromUTF8,
          toUTF8,
          readUTF8File,
          withUTF8FileContents,
          writeUTF8File,
          normaliseLineEndings,
  
          -- * generic utils
          equating,
          comparing,
          isInfixOf,
          intercalate,
          lowercase,
          wrapText,
          wrapLine,
    ) where
  
  import Control.Monad
      ( when, unless, filterM )
  import Control.Concurrent.MVar
      ( newEmptyMVar, putMVar, takeMVar )
  import Data.List
    ( nub, unfoldr, isPrefixOf, tails, intercalate )
  import Data.Char as Char
      ( toLower, chr, ord )
  import Data.Bits
      ( Bits((.|.), (.&.), shiftL, shiftR) )
  import qualified Data.ByteString.Lazy as BS
  import qualified Data.ByteString.Lazy.Char8 as BS.Char8
  
  import System.Directory
      ( getDirectoryContents, doesDirectoryExist, doesFileExist, removeFile
      , findExecutable )
  import System.Environment
      ( getProgName )
  import System.Cmd
      ( rawSystem )
  import System.Exit
      ( exitWith, ExitCode(..) )
  import System.FilePath
      ( normalise, (</>), (<.>)
      , getSearchPath, takeDirectory, splitFileName
      , splitExtension, splitExtensions, splitDirectories )
  import System.Directory
      ( createDirectory, renameFile, removeDirectoryRecursive )
  import System.IO
      ( Handle, openFile, openBinaryFile, openBinaryTempFile
      , IOMode(ReadMode), hSetBinaryMode
      , hGetContents, stderr, stdout, hPutStr, hFlush, hClose )
  import System.IO.Error as IO.Error
      ( isDoesNotExistError, isAlreadyExistsError
      , ioeSetFileName, ioeGetFileName, ioeGetErrorString )
  import System.IO.Error
      ( ioeSetLocation, ioeGetLocation )
  import System.IO.Unsafe
      ( unsafeInterleaveIO )
  import qualified Control.Exception as Exception
  
  import Distribution.Text
      ( display )
  
  import Control.Exception (evaluate)
  import System.Process (runProcess)
  
  import Control.Concurrent (forkIO)
  import System.Process (runInteractiveProcess, waitForProcess)
  #if __GLASGOW_HASKELL__ >= 702
  import System.Process (showCommandForUser)
  #endif
  
  import Distribution.Compat.CopyFile
           ( copyFile, copyOrdinaryFile, copyExecutableFile
           , setFileOrdinary, setFileExecutable, setDirOrdinary )
  import Distribution.Compat.TempFile
           ( openTempFile, createTempDirectory )
  import Distribution.Compat.Exception
           ( IOException, throwIOIO, tryIO, catchIO, catchExit )
  import Distribution.Verbosity
  
  -- ----------------------------------------------------------------------------
  -- Exception and logging utils
  
  dieWithLocation :: FilePath -> Maybe Int -> String -> IO a
  dieWithLocation filename lineno msg =
    ioError . setLocation lineno
            . flip ioeSetFileName (normalise filename)
            $ userError msg
    where
      setLocation Nothing  err = err
      setLocation (Just n) err = ioeSetLocation err (show n)
  
  die :: String -> IO a
  die msg = ioError (userError msg)
  
  topHandler :: IO a -> IO a
  topHandler prog = catchIO prog handle
    where
      handle ioe = do
        hFlush stdout
        pname <- getProgName
        hPutStr stderr (mesage pname)
        exitWith (ExitFailure 1)
        where
          mesage pname = wrapText (pname ++ ": " ++ file ++ detail)
          file         = case ioeGetFileName ioe of
                           Nothing   -> ""
                           Just path -> path ++ location ++ ": "
          location     = case ioeGetLocation ioe of
                           l@(n:_) | n >= '0' && n <= '9' -> ':' : l
                           _                              -> ""
          detail       = ioeGetErrorString ioe
  
  -- | Non fatal conditions that may be indicative of an error or problem.
  --
  -- We display these at the 'normal' verbosity level.
  --
  warn :: Verbosity -> String -> IO ()
  warn verbosity msg =
    when (verbosity >= normal) $ do
      hFlush stdout
      hPutStr stderr (wrapText ("Warning: " ++ msg))
  
  -- | Useful status messages.
  --
  -- We display these at the 'normal' verbosity level.
  --
  -- This is for the ordinary helpful status messages that users see. Just
  -- enough information to know that things are working but not floods of detail.
  --
  notice :: Verbosity -> String -> IO ()
  notice verbosity msg =
    when (verbosity >= normal) $
      putStr (wrapText msg)
  
  -- | More detail on the operation of some action.
  --
  -- We display these messages when the verbosity level is 'verbose'
  --
  info :: Verbosity -> String -> IO ()
  info verbosity msg =
    when (verbosity >= verbose) $
      putStr (wrapText msg)
  
  -- | Detailed internal debugging information
  --
  -- We display these messages when the verbosity level is 'deafening'
  --
  debug :: Verbosity -> String -> IO ()
  debug verbosity msg =
    when (verbosity >= deafening) $ do
      putStr (wrapText msg)
      hFlush stdout
  
  -- | A variant of 'debug' that doesn't perform the automatic line
  -- wrapping. Produces better output in some cases.
  debugNoWrap :: Verbosity -> String -> IO ()
  debugNoWrap verbosity msg =
    when (verbosity >= deafening) $ do
      putStrLn msg
      hFlush stdout
  
  -- | Perform an IO action, catching any IO exceptions and printing an error
  --   if one occurs.
  chattyTry :: String  -- ^ a description of the action we were attempting
            -> IO ()   -- ^ the action itself
            -> IO ()
  chattyTry desc action =
    catchIO action $ \exception ->
      putStrLn $ "Error while " ++ desc ++ ": " ++ show exception
  
  -- -----------------------------------------------------------------------------
  -- Helper functions
  
  -- | Wraps text to the default line width. Existing newlines are preserved.
  wrapText :: String -> String
  wrapText = unlines
           . map (intercalate "\n"
                . map unwords
                . wrapLine 79
                . words)
           . lines
  
  -- | Wraps a list of words to a list of lines of words of a particular width.
  wrapLine :: Int -> [String] -> [[String]]
  wrapLine width = wrap 0 []
    where wrap :: Int -> [String] -> [String] -> [[String]]
          wrap 0   []   (w:ws)
            | length w + 1 > width
            = wrap (length w) [w] ws
          wrap col line (w:ws)
            | col + length w + 1 > width
            = reverse line : wrap 0 [] (w:ws)
          wrap col line (w:ws)
            = let col' = col + length w + 1
               in wrap col' (w:line) ws
          wrap _ []   [] = []
          wrap _ line [] = [reverse line]
  
  -- -----------------------------------------------------------------------------
  -- rawSystem variants
  maybeExit :: IO ExitCode -> IO ()
  maybeExit cmd = do
    res <- cmd
    unless (res == ExitSuccess) $ exitWith res
  
  printRawCommandAndArgs :: Verbosity -> FilePath -> [String] -> IO ()
  printRawCommandAndArgs verbosity path args
   | verbosity >= deafening = print (path, args)
   | verbosity >= verbose   =
  #if __GLASGOW_HASKELL__ >= 702
                              putStrLn $ showCommandForUser path args
  #else
                              putStrLn $ unwords (path : args)
  #endif
   | otherwise              = return ()
  
  printRawCommandAndArgsAndEnv :: Verbosity
                               -> FilePath
                               -> [String]
                               -> [(String, String)]
                               -> IO ()
  printRawCommandAndArgsAndEnv verbosity path args env
   | verbosity >= deafening = do putStrLn ("Environment: " ++ show env)
                                 print (path, args)
   | verbosity >= verbose   = putStrLn $ unwords (path : args)
   | otherwise              = return ()
  
  -- Exit with the same exitcode if the subcommand fails
  rawSystemExit :: Verbosity -> FilePath -> [String] -> IO ()
  rawSystemExit verbosity path args = do
    printRawCommandAndArgs verbosity path args
    hFlush stdout
    exitcode <- rawSystem path args
    unless (exitcode == ExitSuccess) $ do
      debug verbosity $ path ++ " returned " ++ show exitcode
      exitWith exitcode
  
  rawSystemExitCode :: Verbosity -> FilePath -> [String] -> IO ExitCode
  rawSystemExitCode verbosity path args = do
    printRawCommandAndArgs verbosity path args
    hFlush stdout
    exitcode <- rawSystem path args
    unless (exitcode == ExitSuccess) $ do
      debug verbosity $ path ++ " returned " ++ show exitcode
    return exitcode
  
  rawSystemExitWithEnv :: Verbosity
                       -> FilePath
                       -> [String]
                       -> [(String, String)]
                       -> IO ()
  rawSystemExitWithEnv verbosity path args env = do
      printRawCommandAndArgsAndEnv verbosity path args env
      hFlush stdout
      ph <- runProcess path args Nothing (Just env) Nothing Nothing Nothing
      exitcode <- waitForProcess ph
      unless (exitcode == ExitSuccess) $ do
          debug verbosity $ path ++ " returned " ++ show exitcode
          exitWith exitcode
  
  -- Closes the passed in handles before returning.
  rawSystemIOWithEnv :: Verbosity
                     -> FilePath
                     -> [String]
                     -> [(String, String)]
                     -> Maybe Handle  -- ^ stdin
                     -> Maybe Handle  -- ^ stdout
                     -> Maybe Handle  -- ^ stderr
                     -> IO ExitCode
  rawSystemIOWithEnv verbosity path args env inp out err = do
      printRawCommandAndArgsAndEnv verbosity path args env
      hFlush stdout
      ph <- runProcess path args Nothing (Just env) inp out err
      exitcode <- waitForProcess ph
      unless (exitcode == ExitSuccess) $ do
        debug verbosity $ path ++ " returned " ++ show exitcode
      return exitcode
  
  -- | Run a command and return its output.
  --
  -- The output is assumed to be text in the locale encoding.
  --
  rawSystemStdout :: Verbosity -> FilePath -> [String] -> IO String
  rawSystemStdout verbosity path args = do
    (output, errors, exitCode) <- rawSystemStdInOut verbosity path args
                                                    Nothing False
    when (exitCode /= ExitSuccess) $
      die errors
    return output
  
  -- | Run a command and return its output, errors and exit status. Optionally
  -- also supply some input. Also provides control over whether the binary/text
  -- mode of the input and output.
  --
  rawSystemStdInOut :: Verbosity
                    -> FilePath -> [String]
                    -> Maybe (String, Bool) -- ^ input text and binary mode
                    -> Bool                 -- ^ output in binary mode
                    -> IO (String, String, ExitCode) -- ^ output, errors, exit
  rawSystemStdInOut verbosity path args input outputBinary = do
    printRawCommandAndArgs verbosity path args
  
    Exception.bracket
       (runInteractiveProcess path args Nothing Nothing)
       (\(inh,outh,errh,_) -> hClose inh >> hClose outh >> hClose errh)
      $ \(inh,outh,errh,pid) -> do
  
        -- output mode depends on what the caller wants
        hSetBinaryMode outh outputBinary
        -- but the errors are always assumed to be text (in the current locale)
        hSetBinaryMode errh False
  
        -- fork off a couple threads to pull on the stderr and stdout
        -- so if the process writes to stderr we do not block.
  
        err <- hGetContents errh
        out <- hGetContents outh
  
        mv <- newEmptyMVar
        let force str = (evaluate (length str) >> return ())
              `Exception.finally` putMVar mv ()
            --TODO: handle exceptions like text decoding.
        _ <- forkIO $ force out
        _ <- forkIO $ force err
  
        -- push all the input, if any
        case input of
          Nothing -> return ()
          Just (inputStr, inputBinary) -> do
                  -- input mode depends on what the caller wants
            hSetBinaryMode inh inputBinary
            hPutStr inh inputStr
            hClose inh
            --TODO: this probably fails if the process refuses to consume
            -- or if it closes stdin (eg if it exits)
  
        -- wait for both to finish, in either order
        takeMVar mv
        takeMVar mv
  
        -- wait for the program to terminate
        exitcode <- waitForProcess pid
        unless (exitcode == ExitSuccess) $
          debug verbosity $ path ++ " returned " ++ show exitcode
                         ++ if null err then "" else
                            " with error message:\n" ++ err
                         ++ case input of
                              Nothing       -> ""
                              Just ("",  _) -> ""
                              Just (inp, _) -> "\nstdin input:\n" ++ inp
  
        return (out, err, exitcode)
  
  
  -- | Look for a program on the path.
  findProgramLocation :: Verbosity -> FilePath -> IO (Maybe FilePath)
  findProgramLocation verbosity prog = do
    debug verbosity $ "searching for " ++ prog ++ " in path."
    res <- findExecutable prog
    case res of
        Nothing   -> debug verbosity ("Cannot find " ++ prog ++ " on the path")
        Just path -> debug verbosity ("found " ++ prog ++ " at "++ path)
    return res
  
  
  -- | Like the unix xargs program. Useful for when we've got very long command
  -- lines that might overflow an OS limit on command line length and so you
  -- need to invoke a command multiple times to get all the args in.
  --
  -- Use it with either of the rawSystem variants above. For example:
  --
  -- > xargs (32*1024) (rawSystemExit verbosity) prog fixedArgs bigArgs
  --
  xargs :: Int -> ([String] -> IO ())
        -> [String] -> [String] -> IO ()
  xargs maxSize rawSystemFun fixedArgs bigArgs =
    let fixedArgSize = sum (map length fixedArgs) + length fixedArgs
        chunkSize = maxSize - fixedArgSize
     in mapM_ (rawSystemFun . (fixedArgs ++)) (chunks chunkSize bigArgs)
  
    where chunks len = unfoldr $ \s ->
            if null s then Nothing
                      else Just (chunk [] len s)
  
          chunk acc _   []     = (reverse acc,[])
          chunk acc len (s:ss)
            | len' < len = chunk (s:acc) (len-len'-1) ss
            | otherwise  = (reverse acc, s:ss)
            where len' = length s
  
  -- ------------------------------------------------------------
  -- * File Utilities
  -- ------------------------------------------------------------
  
  ----------------
  -- Finding files
  
  -- | Find a file by looking in a search path. The file path must match exactly.
  --
  findFile :: [FilePath]    -- ^search locations
           -> FilePath      -- ^File Name
           -> IO FilePath
  findFile searchPath fileName =
    findFirstFile id
      [ path </> fileName
      | path <- nub searchPath]
    >>= maybe (die $ fileName ++ " doesn't exist") return
  
  -- | Find a file by looking in a search path with one of a list of possible
  -- file extensions. The file base name should be given and it will be tried
  -- with each of the extensions in each element of the search path.
  --
  findFileWithExtension :: [String]
                        -> [FilePath]
                        -> FilePath
                        -> IO (Maybe FilePath)
  findFileWithExtension extensions searchPath baseName =
    findFirstFile id
      [ path </> baseName <.> ext
      | path <- nub searchPath
      , ext <- nub extensions ]
  
  -- | Like 'findFileWithExtension' but returns which element of the search path
  -- the file was found in, and the file path relative to that base directory.
  --
  findFileWithExtension' :: [String]
                         -> [FilePath]
                         -> FilePath
                         -> IO (Maybe (FilePath, FilePath))
  findFileWithExtension' extensions searchPath baseName =
    findFirstFile (uncurry (</>))
      [ (path, baseName <.> ext)
      | path <- nub searchPath
      , ext <- nub extensions ]
  
  findFirstFile :: (a -> FilePath) -> [a] -> IO (Maybe a)
  findFirstFile file = findFirst
    where findFirst []     = return Nothing
          findFirst (x:xs) = do exists <- doesFileExist (file x)
                                if exists
                                  then return (Just x)
                                  else findFirst xs
  
  
  -- | List all the files in a directory and all subdirectories.
  --
  -- The order places files in sub-directories after all the files in their
  -- parent directories. The list is generated lazily so is not well defined if
  -- the source directory structure changes before the list is used.
  --
  getDirectoryContentsRecursive :: FilePath -> IO [FilePath]
  getDirectoryContentsRecursive topdir = recurseDirectories [""]
    where
      recurseDirectories :: [FilePath] -> IO [FilePath]
      recurseDirectories []         = return []
      recurseDirectories (dir:dirs) = unsafeInterleaveIO $ do
        (files, dirs') <- collect [] [] =<< getDirectoryContents (topdir </> dir)
        files' <- recurseDirectories (dirs' ++ dirs)
        return (files ++ files')
  
        where
          collect files dirs' []              = return (reverse files, reverse dirs')
          collect files dirs' (entry:entries) | ignore entry
                                              = collect files dirs' entries
          collect files dirs' (entry:entries) = do
            let dirEntry = dir </> entry
            isDirectory <- doesDirectoryExist (topdir </> dirEntry)
            if isDirectory
              then collect files (dirEntry:dirs') entries
              else collect (dirEntry:files) dirs' entries
  
          ignore ['.']      = True
          ignore ['.', '.'] = True
          ignore _          = False
  
  ------------------------
  -- Environment variables
  
  -- | Is this directory in the system search path?
  isInSearchPath :: FilePath -> IO Bool
  isInSearchPath path = fmap (elem path) getSearchPath
  
  ----------------
  -- File globbing
  
  data FileGlob
     -- | No glob at all, just an ordinary file
     = NoGlob FilePath
  
     -- | dir prefix and extension, like @\"foo\/bar\/\*.baz\"@ corresponds to
     --    @FileGlob \"foo\/bar\" \".baz\"@
     | FileGlob FilePath String
  
  parseFileGlob :: FilePath -> Maybe FileGlob
  parseFileGlob filepath = case splitExtensions filepath of
    (filepath', ext) -> case splitFileName filepath' of
      (dir, "*") | '*' `elem` dir
                || '*' `elem` ext
                || null ext            -> Nothing
                 | null dir            -> Just (FileGlob "." ext)
                 | otherwise           -> Just (FileGlob dir ext)
      _          | '*' `elem` filepath -> Nothing
                 | otherwise           -> Just (NoGlob filepath)
  
  matchFileGlob :: FilePath -> IO [FilePath]
  matchFileGlob = matchDirFileGlob "."
  
  matchDirFileGlob :: FilePath -> FilePath -> IO [FilePath]
  matchDirFileGlob dir filepath = case parseFileGlob filepath of
    Nothing -> die $ "invalid file glob '" ++ filepath
                  ++ "'. Wildcards '*' are only allowed in place of the file"
                  ++ " name, not in the directory name or file extension."
                  ++ " If a wildcard is used it must be with an file extension."
    Just (NoGlob filepath') -> return [filepath']
    Just (FileGlob dir' ext) -> do
      files <- getDirectoryContents (dir </> dir')
      case   [ dir' </> file
             | file <- files
             , let (name, ext') = splitExtensions file
             , not (null name) && ext' == ext ] of
        []      -> die $ "filepath wildcard '" ++ filepath
                      ++ "' does not match any files."
        matches -> return matches
  
  ----------------------------------------
  -- Copying and installing files and dirs
  
  -- | Same as 'createDirectoryIfMissing' but logs at higher verbosity levels.
  --
  createDirectoryIfMissingVerbose :: Verbosity
                                  -> Bool     -- ^ Create its parents too?
                                  -> FilePath
                                  -> IO ()
  createDirectoryIfMissingVerbose verbosity create_parents path0
    | create_parents = createDirs (parents path0)
    | otherwise      = createDirs (take 1 (parents path0))
    where
      parents = reverse . scanl1 (</>) . splitDirectories . normalise
  
      createDirs []         = return ()
      createDirs (dir:[])   = createDir dir throwIOIO
      createDirs (dir:dirs) =
        createDir dir $ \_ -> do
          createDirs dirs
          createDir dir throwIOIO
  
      createDir :: FilePath -> (IOException -> IO ()) -> IO ()
      createDir dir notExistHandler = do
        r <- tryIO $ createDirectoryVerbose verbosity dir
        case (r :: Either IOException ()) of
          Right ()                   -> return ()
          Left  e
            | isDoesNotExistError  e -> notExistHandler e
            -- createDirectory (and indeed POSIX mkdir) does not distinguish
            -- between a dir already existing and a file already existing. So we
            -- check for it here. Unfortunately there is a slight race condition
            -- here, but we think it is benign. It could report an exeption in
            -- the case that the dir did exist but another process deletes the
            -- directory and creates a file in its place before we can check
            -- that the directory did indeed exist.
            | isAlreadyExistsError e -> (do
                isDir <- doesDirectoryExist dir
                if isDir then return ()
                         else throwIOIO e
                ) `catchIO` ((\_ -> return ()) :: IOException -> IO ())
            | otherwise              -> throwIOIO e
  
  createDirectoryVerbose :: Verbosity -> FilePath -> IO ()
  createDirectoryVerbose verbosity dir = do
    info verbosity $ "creating " ++ dir
    createDirectory dir
    setDirOrdinary dir
  
  -- | Copies a file without copying file permissions. The target file is created
  -- with default permissions. Any existing target file is replaced.
  --
  -- At higher verbosity levels it logs an info message.
  --
  copyFileVerbose :: Verbosity -> FilePath -> FilePath -> IO ()
  copyFileVerbose verbosity src dest = do
    info verbosity ("copy " ++ src ++ " to " ++ dest)
    copyFile src dest
  
  -- | Install an ordinary file. This is like a file copy but the permissions
  -- are set appropriately for an installed file. On Unix it is \"-rw-r--r--\"
  -- while on Windows it uses the default permissions for the target directory.
  --
  installOrdinaryFile :: Verbosity -> FilePath -> FilePath -> IO ()
  installOrdinaryFile verbosity src dest = do
    info verbosity ("Installing " ++ src ++ " to " ++ dest)
    copyOrdinaryFile src dest
  
  -- | Install an executable file. This is like a file copy but the permissions
  -- are set appropriately for an installed file. On Unix it is \"-rwxr-xr-x\"
  -- while on Windows it uses the default permissions for the target directory.
  --
  installExecutableFile :: Verbosity -> FilePath -> FilePath -> IO ()
  installExecutableFile verbosity src dest = do
    info verbosity ("Installing executable " ++ src ++ " to " ++ dest)
    copyExecutableFile src dest
  
  -- | Copies a bunch of files to a target directory, preserving the directory
  -- structure in the target location. The target directories are created if they
  -- do not exist.
  --
  -- The files are identified by a pair of base directory and a path relative to
  -- that base. It is only the relative part that is preserved in the
  -- destination.
  --
  -- For example:
  --
  -- > copyFiles normal "dist/src"
  -- >    [("", "src/Foo.hs"), ("dist/build/", "src/Bar.hs")]
  --
  -- This would copy \"src\/Foo.hs\" to \"dist\/src\/src\/Foo.hs\" and
  -- copy \"dist\/build\/src\/Bar.hs\" to \"dist\/src\/src\/Bar.hs\".
  --
  -- This operation is not atomic. Any IO failure during the copy (including any
  -- missing source files) leaves the target in an unknown state so it is best to
  -- use it with a freshly created directory so that it can be simply deleted if
  -- anything goes wrong.
  --
  copyFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO ()
  copyFiles verbosity targetDir srcFiles = do
  
    -- Create parent directories for everything
    let dirs = map (targetDir </>) . nub . map (takeDirectory . snd) $ srcFiles
    mapM_ (createDirectoryIfMissingVerbose verbosity True) dirs
  
    -- Copy all the files
    sequence_ [ let src  = srcBase   </> srcFile
                    dest = targetDir </> srcFile
                 in copyFileVerbose verbosity src dest
              | (srcBase, srcFile) <- srcFiles ]
  
  -- | This is like 'copyFiles' but uses 'installOrdinaryFile'.
  --
  installOrdinaryFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO ()
  installOrdinaryFiles verbosity targetDir srcFiles = do
  
    -- Create parent directories for everything
    let dirs = map (targetDir </>) . nub . map (takeDirectory . snd) $ srcFiles
    mapM_ (createDirectoryIfMissingVerbose verbosity True) dirs
  
    -- Copy all the files
    sequence_ [ let src  = srcBase   </> srcFile
                    dest = targetDir </> srcFile
                 in installOrdinaryFile verbosity src dest
              | (srcBase, srcFile) <- srcFiles ]
  
  -- | This installs all the files in a directory to a target location,
  -- preserving the directory layout. All the files are assumed to be ordinary
  -- rather than executable files.
  --
  installDirectoryContents :: Verbosity -> FilePath -> FilePath -> IO ()
  installDirectoryContents verbosity srcDir destDir = do
    info verbosity ("copy directory '" ++ srcDir ++ "' to '" ++ destDir ++ "'.")
    srcFiles <- getDirectoryContentsRecursive srcDir
    installOrdinaryFiles verbosity destDir [ (srcDir, f) | f <- srcFiles ]
  
  ---------------------------------
  -- Deprecated file copy functions
  
  {-# DEPRECATED copyDirectoryRecursiveVerbose
        "You probably want installDirectoryContents instead" #-}
  copyDirectoryRecursiveVerbose :: Verbosity -> FilePath -> FilePath -> IO ()
  copyDirectoryRecursiveVerbose verbosity srcDir destDir = do
    info verbosity ("copy directory '" ++ srcDir ++ "' to '" ++ destDir ++ "'.")
    srcFiles <- getDirectoryContentsRecursive srcDir
    copyFiles verbosity destDir [ (srcDir, f) | f <- srcFiles ]
  
  ---------------------------
  -- Temporary files and dirs
  
  -- | Use a temporary filename that doesn't already exist.
  --
  withTempFile :: Bool     -- ^ Keep temporary files?
               -> FilePath -- ^ Temp dir to create the file in
               -> String   -- ^ File name template. See 'openTempFile'.
               -> (FilePath -> Handle -> IO a) -> IO a
  withTempFile keepTempFiles tmpDir template action =
    Exception.bracket
      (openTempFile tmpDir template)
      (\(name, handle) -> do hClose handle
                             unless keepTempFiles $ removeFile name)
      (uncurry action)
  
  -- | Create and use a temporary directory.
  --
  -- Creates a new temporary directory inside the given directory, making use
  -- of the template. The temp directory is deleted after use. For example:
  --
  -- > withTempDirectory verbosity "src" "sdist." $ \tmpDir -> do ...
  --
  -- The @tmpDir@ will be a new subdirectory of the given directory, e.g.
  -- @src/sdist.342@.
  --
  withTempDirectory :: Verbosity
                    -> Bool     -- ^ Keep temporary files?
                    -> FilePath -> String -> (FilePath -> IO a) -> IO a
  withTempDirectory _verbosity keepTempFiles targetDir template =
    Exception.bracket
      (createTempDirectory targetDir template)
      (unless keepTempFiles . removeDirectoryRecursive)
  
  -----------------------------------
  -- Safely reading and writing files
  
  -- | Gets the contents of a file, but guarantee that it gets closed.
  --
  -- The file is read lazily but if it is not fully consumed by the action then
  -- the remaining input is truncated and the file is closed.
  --
  withFileContents :: FilePath -> (String -> IO a) -> IO a
  withFileContents name action =
    Exception.bracket (openFile name ReadMode) hClose
                      (\hnd -> hGetContents hnd >>= action)
  
  -- | Writes a file atomically.
  --
  -- The file is either written sucessfully or an IO exception is raised and
  -- the original file is left unchanged.
  --
  -- On windows it is not possible to delete a file that is open by a process.
  -- This case will give an IO exception but the atomic property is not affected.
  --
  writeFileAtomic :: FilePath -> BS.ByteString -> IO ()
  writeFileAtomic targetPath content = do
    let (targetDir, targetFile) = splitFileName targetPath
    Exception.bracketOnError
      (openBinaryTempFile targetDir $ targetFile <.> "tmp")
      (\(tmpPath, handle) -> hClose handle >> removeFile tmpPath)
      (\(tmpPath, handle) -> do
          BS.hPut handle content
          hClose handle
          renameFile tmpPath targetPath)
  
  -- | Write a file but only if it would have new content. If we would be writing
  -- the same as the existing content then leave the file as is so that we do not
  -- update the file's modification time.
  --
  rewriteFile :: FilePath -> String -> IO ()
  rewriteFile path newContent =
    flip catchIO mightNotExist $ do
      existingContent <- readFile path
      _ <- evaluate (length existingContent)
      unless (existingContent == newContent) $
        writeFileAtomic path (BS.Char8.pack newContent)
    where
      mightNotExist e | isDoesNotExistError e = writeFileAtomic path
                                                (BS.Char8.pack newContent)
                      | otherwise             = ioError e
  
  -- | The path name that represents the current directory.
  -- In Unix, it's @\".\"@, but this is system-specific.
  -- (E.g. AmigaOS uses the empty string @\"\"@ for the current directory.)
  currentDir :: FilePath
  currentDir = "."
  
  -- ------------------------------------------------------------
  -- * Finding the description file
  -- ------------------------------------------------------------
  
  -- |Package description file (/pkgname/@.cabal@)
  defaultPackageDesc :: Verbosity -> IO FilePath
  defaultPackageDesc _verbosity = findPackageDesc currentDir
  
  -- |Find a package description file in the given directory.  Looks for
  -- @.cabal@ files.
  findPackageDesc :: FilePath    -- ^Where to look
                  -> IO FilePath -- ^<pkgname>.cabal
  findPackageDesc dir
   = do files <- getDirectoryContents dir
        -- to make sure we do not mistake a ~/.cabal/ dir for a <pkgname>.cabal
        -- file we filter to exclude dirs and null base file names:
        cabalFiles <- filterM doesFileExist
                         [ dir </> file
                         | file <- files
                         , let (name, ext) = splitExtension file
                         , not (null name) && ext == ".cabal" ]
        case cabalFiles of
          []          -> noDesc
          [cabalFile] -> return cabalFile
          multiple    -> multiDesc multiple
  
    where
      noDesc :: IO a
      noDesc = die $ "No cabal file found.\n"
                  ++ "Please create a package description file <pkgname>.cabal"
  
      multiDesc :: [String] -> IO a
      multiDesc l = die $ "Multiple cabal files found.\n"
                      ++ "Please use only one of: "
                      ++ intercalate ", " l
  
  -- |Optional auxiliary package information file (/pkgname/@.buildinfo@)
  defaultHookedPackageDesc :: IO (Maybe FilePath)
  defaultHookedPackageDesc = findHookedPackageDesc currentDir
  
  -- |Find auxiliary package information in the given directory.
  -- Looks for @.buildinfo@ files.
  findHookedPackageDesc
      :: FilePath                 -- ^Directory to search
      -> IO (Maybe FilePath)      -- ^/dir/@\/@/pkgname/@.buildinfo@, if present
  findHookedPackageDesc dir = do
      files <- getDirectoryContents dir
      buildInfoFiles <- filterM doesFileExist
                          [ dir </> file
                          | file <- files
                          , let (name, ext) = splitExtension file
                          , not (null name) && ext == buildInfoExt ]
      case buildInfoFiles of
          [] -> return Nothing
          [f] -> return (Just f)
          _ -> die ("Multiple files with extension " ++ buildInfoExt)
  
  buildInfoExt  :: String
  buildInfoExt = ".buildinfo"
  
  -- ------------------------------------------------------------
  -- * Unicode stuff
  -- ------------------------------------------------------------
  
  -- This is a modification of the UTF8 code from gtk2hs and the
  -- utf8-string package.
  
  fromUTF8 :: String -> String
  fromUTF8 []     = []
  fromUTF8 (c:cs)
    | c <= '\x7F' = c : fromUTF8 cs
    | c <= '\xBF' = replacementChar : fromUTF8 cs
    | c <= '\xDF' = twoBytes c cs
    | c <= '\xEF' = moreBytes 3 0x800     cs (ord c .&. 0xF)
    | c <= '\xF7' = moreBytes 4 0x10000   cs (ord c .&. 0x7)
    | c <= '\xFB' = moreBytes 5 0x200000  cs (ord c .&. 0x3)
    | c <= '\xFD' = moreBytes 6 0x4000000 cs (ord c .&. 0x1)
    | otherwise   = replacementChar : fromUTF8 cs
    where
      twoBytes c0 (c1:cs')
        | ord c1 .&. 0xC0 == 0x80
        = let d = ((ord c0 .&. 0x1F) `shiftL` 6)
               .|. (ord c1 .&. 0x3F)
           in if d >= 0x80
                 then  chr d           : fromUTF8 cs'
                 else  replacementChar : fromUTF8 cs'
      twoBytes _ cs' = replacementChar : fromUTF8 cs'
  
      moreBytes :: Int -> Int -> [Char] -> Int -> [Char]
      moreBytes 1 overlong cs' acc
        | overlong <= acc && acc <= 0x10FFFF
       && (acc < 0xD800 || 0xDFFF < acc)
       && (acc < 0xFFFE || 0xFFFF < acc)
        = chr acc : fromUTF8 cs'
  
        | otherwise
        = replacementChar : fromUTF8 cs'
  
      moreBytes byteCount overlong (cn:cs') acc
        | ord cn .&. 0xC0 == 0x80
        = moreBytes (byteCount-1) overlong cs'
            ((acc `shiftL` 6) .|. ord cn .&. 0x3F)
  
      moreBytes _ _ cs' _
        = replacementChar : fromUTF8 cs'
  
      replacementChar = '\xfffd'
  
  toUTF8 :: String -> String
  toUTF8 []        = []
  toUTF8 (c:cs)
    | c <= '\x07F' = c
                   : toUTF8 cs
    | c <= '\x7FF' = chr (0xC0 .|. (w `shiftR` 6))
                   : chr (0x80 .|. (w .&. 0x3F))
                   : toUTF8 cs
    | c <= '\xFFFF'= chr (0xE0 .|.  (w `shiftR` 12))
                   : chr (0x80 .|. ((w `shiftR` 6)  .&. 0x3F))
                   : chr (0x80 .|.  (w .&. 0x3F))
                   : toUTF8 cs
    | otherwise    = chr (0xf0 .|.  (w `shiftR` 18))
                   : chr (0x80 .|. ((w `shiftR` 12)  .&. 0x3F))
                   : chr (0x80 .|. ((w `shiftR` 6)  .&. 0x3F))
                   : chr (0x80 .|.  (w .&. 0x3F))
                   : toUTF8 cs
    where w = ord c
  
  -- | Ignore a Unicode byte order mark (BOM) at the beginning of the input
  --
  ignoreBOM :: String -> String
  ignoreBOM ('\xFEFF':string) = string
  ignoreBOM string            = string
  
  -- | Reads a UTF8 encoded text file as a Unicode String
  --
  -- Reads lazily using ordinary 'readFile'.
  --
  readUTF8File :: FilePath -> IO String
  readUTF8File f = fmap (ignoreBOM . fromUTF8)
                 . hGetContents =<< openBinaryFile f ReadMode
  
  -- | Reads a UTF8 encoded text file as a Unicode String
  --
  -- Same behaviour as 'withFileContents'.
  --
  withUTF8FileContents :: FilePath -> (String -> IO a) -> IO a
  withUTF8FileContents name action =
    Exception.bracket
      (openBinaryFile name ReadMode)
      hClose
      (\hnd -> hGetContents hnd >>= action . ignoreBOM . fromUTF8)
  
  -- | Writes a Unicode String as a UTF8 encoded text file.
  --
  -- Uses 'writeFileAtomic', so provides the same guarantees.
  --
  writeUTF8File :: FilePath -> String -> IO ()
  writeUTF8File path = writeFileAtomic path . BS.Char8.pack . toUTF8
  
  -- | Fix different systems silly line ending conventions
  normaliseLineEndings :: String -> String
  normaliseLineEndings [] = []
  normaliseLineEndings ('\r':'\n':s) = '\n' : normaliseLineEndings s -- windows
  normaliseLineEndings ('\r':s)      = '\n' : normaliseLineEndings s -- old osx
  normaliseLineEndings (  c :s)      =   c  : normaliseLineEndings s
  
  -- ------------------------------------------------------------
  -- * Common utils
  -- ------------------------------------------------------------
  
  equating :: Eq a => (b -> a) -> b -> b -> Bool
  equating p x y = p x == p y
  
  comparing :: Ord a => (b -> a) -> b -> b -> Ordering
  comparing p x y = p x `compare` p y
  
  isInfixOf :: String -> String -> Bool
  isInfixOf needle haystack = any (isPrefixOf needle) (tails haystack)
  
  lowercase :: String -> String
  lowercase = map Char.toLower
  
  