On Wed, Apr 23, 2025 at 8:39 AM Christoph Berg <myon@debian.org> wrote:
> This will cause problems when programs are running while packages are
> updated on disk. That program then tries to dlopen 18-0.so when there
> is already 18-1.so installed. Relevant when the first oauth connection
> is made way after startup.
Ugh, good point. This hazard applies to the previous suggestion of
pkglibdir, too, but in that case it would have been silent...
> This is trading one problem for another, but within-a-major ABI
> changes should be much rarer than normal minor updates with
> applications restarting only later.
But the consequences are much worse for a silent ABI mismatch. Imagine
if libpq-oauth examines the wrong pointer inside PGconn for a
security-critical check.
> Alternatively, there could be a dedicated SONAME for the plugin that
> only changes when necessary, but perhaps the simple "18.so" solution
> is good enough.
I don't think SONAME helps us, does it? We're not using it in dlopen().
We could all agree to bump the second number in the filename whenever
there's an internal ABI change. That works from a technical
perspective, but it's hard to test and enforce and... just not forget.
Or, I may still be able to thread the needle with a fuller lookup
table, and remove the dependency on libpq-int.h; it's just not going
to be incredibly pretty. Thinking...
Thanks so much for your continued review!
--Jacob
