This is needed for the change to make "read-tree" just read into the
cache (and then you do a "checkout-cache" to update your current dir
contents).

It's supposed to test the returned file type, not think that read_sha1_file()
tests it. Confusion from "cat-file" command line usage.

Make the warnings have newlines, and don't stop "checkout-cache -a"
just because a file already exists.

I'll also eventually change "read-tree" to only update the cache
information, instead of doing a checkout of the tree. Much nicer.

Like the cache filename finder, it's a generically useful function,
rather than something specific to the current "show-diff" thing.

It finds the cache entry position for a given name, and is
generally useful. Sure, everybody can just scan the active
cache array, but since it's sorted, you actually want to
search it with a binary search, so let's not duplicate that
logic all over the place.

Patches from Dave Jones and Ingo Molnar, but since I don't have any
infrastructure in place to use the old patch applicator scripts I
am trying to build up, I ended up fixing the thing by hand instead.

Credit where credit is due, though. Nice to see that people are
taking a look at the project even in this early stage.

internal format.

This doesn't yet check the reachability information, but we're getting
there.. Slowly.

Not all Linux distributions seem to need it (notably not YDL on ppc64), but
enough ones obviously do.

This is what happens when there are no nice tools to tell you to do things
properly.

It doesn't complain about mine. But it also doesn't yet check for
inter-object reachability etc.

And fix up header declarations.

This allows us to also actually check the sha1 hash using these
routines. Needed for the "fsck" thing.

And fix up the warnings that it pointed out. Let's keep the tree
clean from early on.

Not that the code is very beautiful anyway ;)

New syntax: "cat-file -t <sha1>" shows the tag, while "cat-file <tag> <sha1>"
outputs the file contents after checking that the supplied tag matches.

I needed this to make a "sparse" archive conversion from my old
BitKeeper tree data. The scripts to do the conversion are just
incredibly ugly, but they seem to validate the notion that you
can actually use this silly 'git' thing to save your history in.

The tool interface sucks (especially "committing" information, which is just
me doing everything by hand from the command line), but I think this is in
theory actually a viable way of describing the world. So copyright it.