[Rpm-maint] [rpm-software-management/rpm] Rpm query causes corruption in the file-backed mmaped bdb regions (#232)

[Jeff Johnson]

Once a dbenv is damaged for whatever reason (including reboots, segfaults, bugs, whatever), all future accesses are going to report DB_RUNRECOVERY.

(aside)
The right fix when DB_RUNRECOVERY is  returned: (drum roll please) to run a recovery and repeat the open once.

RPM hysterically (I don't known the current rpm.org implementation, but am about to look) also reopens an rpmdb/dbenv to achieve RDONLY -> RDWR, and unlinks dbenv files (trusting that the .dbenv lock is sufficient protection.

Both the reopen/removal open race windows, where there are no locks held (except .dbenv.lock) because the dbenv is closed, or because the dbenv cannot be shared.

The approaches using DB_PRIVATE, or not using a dbenv as non-root, are all equivalent to not locking.

Off to look at sources and view "endless row of bugs" with BDB ...


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