Paul Eggert <eggert@cs.ucla.edu> skribis:

> Ludovic Courtès wrote:
>> I think the problem happens when ‘tail’ opens ‘foo’ right in between of
>> the two notifications: ‘foo’ is still there, and so ‘tail’ doesn’t
>> report anything.
>>
>> Does that make sense?
>
> Yes, though if the link count is indeed zero, I'm surprised that
> 'tail' can open the file -- that sounds like a bug in the kernel.

Attached is a reproducer; just run it in a loop for a couple of seconds:

--8<---------------cut here---------------start------------->8---
$ while ./a.out ; do : ; done
funny, errno = Success, nlink = 0
Aborted (core dumped)
--8<---------------cut here---------------end--------------->8---

I’m not sure if that’s a kernel bug.  Strictly speaking, inotify works
as expected: we get a notification for nlink--, which doesn’t mean the
file has vanished.

The conclusion for ‘tail’ would be to wait for the IN_DELETE_SELF event
before considering the file to be gone.  WDYT?

(That ‘inotify_rm_watch’ returns EINVAL *is* a bug IMO, but not
worrisome.)

Thanks,
Ludo’.