Re: [Bug-tar] opening files with O_NONBLOCK causes problems

[Paul Eggert]

On 01/04/12 07:20, Vitezslav Cizek wrote:
> Opening an
> offline file with O_NONBLOCK and issuing a read(2) tells DMF (HSM software)
> to initiate recall of the file, but the O_NONBLOCK tells DMF to not block the
> process

Thanks for reporting the problem.  GNU tar uses O_NONBLOCK for security reasons,
to avoid problems when attackers substitute special files for regular ones
just before tar opens them.  I suppose we could change tar to use fcntl
to disable O_NONBLOCK between the time that tar opens a regular file and
the time it reads or writes to it.  Would that work with DMF?

Is there a manual somewhere that describes DMF and how it deals with O_NONBLOCK?

I have the feeling that tar won't be the only app that runs into this 
problem....