The earlier fix answered 503 to every read and write of a settings file
or plugin vault that doesn't decrypt, so a rotated SESSION_SECRET left
the user with no way out: even disconnecting a plugin failed. Now such a
document reads as nothing stored, and the next write first moves it
aside, then saves as usual. The bytes are kept unchanged, so the data can
be restored with the old secret:
- local mode renames the file to `<file>.unreadable-<time>` next to it
- shared mode copies the document to `<id>.unreadable-<time>`, then
deletes the original only if it is still the same document
A settings file too short to hold anything reads as nothing stored and
is written over, as before 585e10041. The 503 is now only for a shared
store that can't be reached or a file that can't be read at all.
Credentials the admin set up for a plugin no longer read the user's
vault, so they keep working when it can't be read, and the credential
list still reports their status.
Linus Rath
Pascal Dietrich
Linus Rath