Revert "Pack: do not leak file handles"

This reverts commit ae872fc.

The fix in ae872fc was not the best idea, because it forced
reading entire input file in memory, which could be infeasible.

Author: Bodigrim

Codec/Archive/Tar/Pack.hs

@@ -44,7 +44,7 @@ import Data.Time.Clock
 import Data.Time.Clock.POSIX
          ( utcTimeToPOSIXSeconds )
 import System.IO
-         ( IOMode(ReadMode), withBinaryFile, hFileSize )
+         ( IOMode(ReadMode), openBinaryFile, hFileSize )
 import System.IO.Unsafe (unsafeInterleaveIO)
 import Control.Exception (throwIO, SomeException)
 import Codec.Archive.Tar.Check.Internal (checkSecurity)
@@ -132,8 +132,9 @@ packFileEntry :: FilePath -- ^ Full path to find the file on the local disk
 packFileEntry filepath tarpath = do
   mtime   <- getModTime filepath
   perms   <- getPermissions filepath
-  content <- BS.readFile filepath
-  let size = BS.length content
+  file    <- openBinaryFile filepath ReadMode
+  size    <- hFileSize file
+  content <- BS.hGetContents file
   return (simpleEntry tarpath (NormalFile content (fromIntegral size))) {
          entryPermissions = if executable perms then executableFilePermissions
                                                 else ordinaryFilePermissions,