metazip 0.1

metazip project is an Apache 2.0 module that allows you to serve dynamically-constructed, uncompressed zip files. Thus, your users can choose to download individual files or entire collections, but you dont have to reserve disk space for both.
Main features:
- Extremely efficient, by hooking into Apaches filter system.
- Works equally well for zip, tar, and other archive files.
- Supports resumption of aborted downloads.
- Lightweight, self-contained C implementation.
- Free, open source license (Apache).
Version restrictions:
- Works for uncompressed archives only.
- Requires command line utility to construct .zip.mz "template" file.
- Currently only supported on Linux with GNU bash, gcc, and make.
metazip works by comparing a real, uncompressed archive to the files it contains. It then constructs a special .mz file that contains the "difference" between the files and the archive. This difference contains the metadata that the archive tool uses to extract the files. metazip does not interpret this metadata; it simply records it in the .mz file. After the .mz file has been created, the original archive file can be deleted. Simply place the newly-created .mz file in the same directory as the files it references. The mz command-line utility takes care of most of the details.
When the .mz file is requested, metazip "glues together" the files and the contents of the .mz file to reconstruct the archive file. Because metazip hooks into Apaches filter system, Apache handles all of the heavy lifting. metazip merely creates some high-level data structures.
Therefore, metazips overhead is practically negligible. In addition, Apaches normal functions for resuming aborted downloads, calculating the content length, setting headers, etc. work identically for static files and for metazips dynamically-generated output.
[Note: The only "catch" is that metazip must be prepared to handle its input in arbitrary-sized chunks (called "bucket brigades" in Apache-speak), even though in practice the input will generally be in one large buffer (because its input is the small .mz file). This is reflected in metazips code structure (in metazip.c), but is completely transparent to you.]