Created attachment 77577 [details] [review]
Fix typo.

I think it's just a typo, check the attached patch.

Sometimes, skipping backwards with a match that yields the empty set will not return 0, but will successfully skip the requested number of items.  The next call to sd_journal_next will then correctly return 0.

To reproduce, find two matches that are independently non-empty, but whose intersection is empty, and then use them with "journalctl -n10" or similar.

For example:

  # journalctl PRIORITY=2
  <some output>
  # journalctl _PID=1
  <some other output>
  # journalctl PRIORITY=2 _PID=1
  <empty>

But

  # journalctl -n10 PRIORITY=2 _PID=1
  <one entry>

You might need to swap the match expressions:

  # journalctl -n10 _PID=1 PRIORITY=2

As mentioned, I think this is just a typo in next_for_match for the DIRECTION_UP case.  The attached patch seems to fix all incorrect behavior that I could find.