Need freely-distributable C database library

[David Elliott]

I need a database library for a project I am working on.  I hesitate
to call it a "database", because it's more like a simple hierarchical
filesystem inside a file than a database.

The requirements are:

	* Freely distributable

	* Single key per record (keys will look a lot like pathnames
		due to hierarchical nature of the data) with reasonably
		long key length (1024 bytes for entire key is fine)

	* Variable record size - from a few bytes to over a megabyte
		(this leaves out dbm/ndbm on Unix)

	* No restrictions on content - may contain ASCII text, images,
		or binaries

	* An entire database must be able to be fit in a single file
		(no .pag/.dir combinations unless .dir can be
		recreated on the fly)

In other words, except for the last item, I need a Unix filesystem
that can live in a single file.

For now, I am implementing the database as a Unix directory structure,
and will probably keep that as an option later, but I want the data
to be transportable in a single file at some point in the future.