LIMITATIONS
===========

Archive:
- Wrong mtime, chown, chgrp for symlinks extracted from the archive. 
  --> lchown, lchgrp are not (yet) implemented in PHP. 
  --> Touch resolves the symlink.
- Cannot write to Gzip filtered files: [ compress.zlib://my_file.tar.gz ].
  --> Zlib doesn't support reading and writing ("r+", "w+") mode.
- Cannot write to Bzip2 filtered files: [ compress.bzip2://my_file.tar.bz2 ].
  --> AFAIK Bzip2 doesn't support reading and writing ("r+", "w+") mode.
  
Tar:
- Make it possible to use a blocksize other than 20 in a tar archive.
- Pax: Writing to archive is not implemented.
- Gnu: Writing to archive is not implemented.

Zip:
- Text or binary-file bit is not set in the (created) archive.
- Extracting of a file is done all in memory. 
  --> Extracting a deflated file without a header is recently fixed in PHP. 
      (Use string filter)
- Check the bitflag, because it is now always 0.
- We use the same version as InfoZip (10). 
- Files are always compressed with the deflate algorithm.
  --> Need to find out the best algorithm. E.g. no compression on small files 
      or files that are already compressed.
- Zip64 is not implemented.

File:
- Common functions from character and blockfile must be moved to ArchiveFile.
- Emulated search with whence SEEK_END is not implemented.
  --> Needed for Bzip2, which doesn't support seeking.

Tests:
- Some tests use executables: tar, gzip, bzip2 and will probably not work on 
  other machines or platforms.