arcgzip.py is an alternative python gzip library, of which focus is on the full support of gzip metadata.

Specifically, this library enables you to ...

• extract all of the meta information defined in RFC-1952.
• create an archive with fine-tuned hearder data.
• handle multiple files in a single gzip archive.

• Python 3.2 or later required (Python 2.7 is also supported)

• Download the source code and run 'setup.py':

  $ python setup.py install

arcgzip.py -l archive.gz         - Show the list of contents.
arcgzip.py -a archive.gz targets - Add target files to the archive.
arcgzip.py -c archive.gz targets - Create a new archive from target files.
arcgzip.py -d archive.gz targets - Extract files from the archive,

--ascii        - Set ASCII text flag.
--crc16        - Add crc16 checksum field to the header.
--comment [S]  - Add file comments for the file.
--content [S]  - Write the string to archive (instead of target files)
--encoding [S] - Specify the encoding of the string (with --content)
--exfield [B]  - Set the base64-encoded data to the extra field.
--level [N]    - Compression level to be used (1-fastest/9-slowest)

• Support stream input.
• Implement iterator interface on GzipFile class.
• Add functional tests for command-line options.
• Improve the output format of 'LIST' mode.

Belows are some thoughts on the design issues of arcgzip.

• Some user may find it useful if arcgzip provides 'no-strict' mode which skips all the CRC16/CRC32/ISIZE checks.
• It might be good idea to provide an accommodating interface to 'exfield' assuming anyone actually makes use of the data field.
• To support stream input, we will need to implement the I/O wrapper that enable seeking (for some extent, at least) by buffering the input bytes. Is there any standard library that can be used to build that feature?
• Currently arcgzip buffers all the file contents in memory while decompressing. It's awkward, but it has an advantage that extracted file object doesn't mess the original file pointer of GzipFile.
• Pickling the GzipInfo array effectively serves as an extrenal index file.