Re: [RFC] a corner case of open(2)

From: Cedric Blancher
Date: Tue Apr 26 2016 - 14:05:57 EST


Existing UNIX behaviour is better. Also, for open() a directory,
remember that int fd=open(), fchdir(fd) must work.

Ced

On 26 April 2016 at 19:55, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
> According to POSIX (and behaviour on other Unices) the following
> should succeed: open("/tmp", O_CREAT, 0) does not have O_EXCL and the pathname
> does refer to existing object, so O_CREAT is ignored and the call is
> equivalent to open("/tmp", 0), which succeeds.
>
> We have it rejected with EISDIR. The thing is, the standard behaviour
> is actually less messy wrt code, and do_last()/lookup_open()/atomic_open()
> badly needs untangling.
>
> Another place where we produce a bogus EISDIR is O_CREAT|O_EXCL on
> an existing directory. POSIX (and other Unices) have EEXIST there. In some
> cases we produce EEXIST, in some - EISDIR. Uniform EEXIST is actually easier.
>
> It is a change of user-visible behaviour, but I would be very
> surprised if anything broke from that change. And it would help to simplify
> the awful mess we have in there.
>
> Comments?
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--
Cedric Blancher <cedric.blancher@xxxxxxxxx>
Institute Pasteur