Re: how does O_NOCTTY help? [Re: bug in chdir-safer

[Jim Meyering]

Jim Meyering <address@hidden> wrote:
> I wrote:
>> Adding O_DIRECTORY is an improvement, even for systems that do have
>> O_NOFOLLOW, but how does O_NOCTTY help?  Isn't the goal of using O_NOCTTY
>> to avoid provoking a signal upon e.g., read while backgrounded?  But
>> chdir_no_follow never attempts a read; all it does is call fstat and close.
>>
>> Is there some other reason to use O_NOCTTY here?
>
> Just so you know, I do know that O_NOCTTY prevents setting the process's
> controlling terminal.  The question is how can setting the controlling
> terminal cause trouble if we're guaranteed never to read from or write
> to the corresponding file descriptor.

Following up to myself again, and maybe answering my own question :-)

I suppose there'd be no harm, per se, in omitting O_NOCTTY, but that
the omission might make open do a tiny bit of unnecessary work.