Re: [PATCH] race between util_create_path() and util_delete_path()?

[Lennart Poettering <lennart@poettering.net>]

On Sat, 05.09.09 19:11, Florian Zumbiehl (florz@florz.de) wrote:

> > All Unix locking APIs are broken in one way or the other. But if you
> > use one then at least use fcntl(F_SETLK) which is the least broken.
> 
> What exactly is broken in flock() (that affects this use)?

The simple fact that fcntl() style locks are the ones that are least
broken and using everything else is confusing since the different lock
styles are independant of each other.

So if you do use locking then use fcntl. 

Now, fcntl is broken in many ways. For example it is unusable for
files that are accessible for other users. It is bound to a process
and not to an fd, and hence useless in threads, and in libraries. The
first close() breaks all locks of a process on a file even if it has
more fds open to it.

In this case you might be able to get away with a lot, but still
that leaves that fcntl is POSIX and the least broken and is the only
flavour of locking that should be used these days.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
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