patching incorrect versions...

[Ryan C. Gordon]

Let's say productX is at version 1.02 on a user's machine. There's a 1.03
patch and then a 1.04 patch.

The foolish user hates loki_update and decides to download the 1.04 patch
directly. Being foolish, he doesn't get the 1.03 patch first. This happens
a lot in the real world, apparently.

loki_patch makes no attempt to verify that 1.04 is the next logical thing
to install, usually leaving half the files updated before it mangles
something and gives up.

The questions:
1) can loki_patch check that the version it is applying is what applies
over the currently installed version? Obviously, loki_update handles this
before running loki_patch, but it's way to easy to circumvent this and
mangle your system.

If nothing else, a workaround is to have a "THIS-IS-VERSION-1.02" file
installed, and make sure it's the first thing in patch.dat (and just
delete it and add THIS-IS-VERSION-1.03, etc...hacky, but it might work).

2) Can loki_patch build patches in a temp directory so that catastrophic
failure (files unexpectedly changed, loki_patch segfaults, out of disk
space, etc) doesn't leave the user with a half-upgraded (read: "ruined")
installation? All patched files (followed by those that are to be deleted)
then get moved into the appropriate place...then again, this can still
fail, but it seems less likely. Thoughts?

--ryan.