Archives based on the zip file format support several features built into
the zip file format. Per-file and whole-archive metadata is stored in
the zip file comment and zip archive comment as a serialized string. Pre-existing
zip comments will be successfully read as a string. Per-file compression
read/write is supported with zlib DEFLATE compression, and read access is supported
with bzip2 compression. There is no limit on the number of files
within a zip-based phar archive. Empty directories are stored in the zip archive
as files with a trailing slash like my/directory/