[wp-hackers] Upgrade sanity checks

[Otto]

Whenever an upgrade comes out, one of the things that we get a lot of
on the support forums is failed upgrades. The main reasons for these
failures are:

1. Database is setup without correct update permissions, so changes to
table structures fail and upgrade.php isn't smart enough to detect it.

2. Users fail to upload all the files to their site, and so unexpected
errors occur. Usually this is the result of some kind of FTP issue
where they simply fail to overwrite all the files (this happens so
often that we always recommend deleting the old version before
uploading the new one), occasionally it's simple user error.

Now, I've seen a trac ticket for case #1 before (and that can be
solved by better error handling in upgrade.php), so I was thinking
about case #2. Is it possible for the upgrade.php file to perform a
sanity check, and make sure that all the WordPress files are present
and correct?

One way would be to have it load some other file which is a list of
all the WordPress files, then check (and potentially hash) them all to
ensure that they are unchanged. Every time a new release occurred,
that file would need to be generated as part of the release process.
Of course, you would want a failure to not *stop* the upgrade, but to
get confirmation. The best user experience would be to put up a
warning message saying "These WordPress files don't appear to be the
correct versions: (list of files here). Proceed with upgrade anyway?
WARNING: Proceeding may cause unexpected results! Do not proceed
without knowing what you're doing. (Proceed / For the love of god
stop!)"

Just an idea. Bounce it around.

-Otto