My favorite pet bug (2004): Yum mishandles Ctrl-C

[Konstantin Ryabitsev]

On 9/6/06, Leszek Matok <Lam at lam.pl> wrote:
> transaction:
> echo "mv -f file.bak file" > backlog
> mv file file.bak
> cp -f file.new file # actual work, this can break
> rm -f file.bak backlog
>
> error recovery on next run:
> if [ -f backlog ]
>         sh backlog
> fi
>
> Do you know a file system that can't do this?

Well, this doesn't work because of %pre, %post, %preun, %postun,
%trigger, etc. If %post touches a file in /etc, you can't restore old
files listed in the %files section and honestly expect everything to
continue to work as if nothing happened. It's for this same reason why
yum doesn't handle package downgrading and rollbacks -- there is no
100% safe way to perform them, so yum doesn't even try.

With the way RPM is designed, unless you can do a filesystem-level
rollback to a pre-transaction state, you shouldn't abort a
transaction. Without that, everything is going to be a fragile hack
that can leave things really, really broken.


Regards,
-- 
Konstantin Ryabitsev
Montréal, Québec