> On Sep 7, 2019, at 9:58 AM, Linus Torvalds <torva...@linux-foundation.org>
> wrote:
>
>> On Sat, Sep 7, 2019 at 5:40 AM Jeff Layton <jlay...@kernel.org> wrote:
>>
>> After thinking about this a bit, I wonder if we might be better served
>> with a new set of OA2_* flags instead of repurposing the O_* flags?
>
> I'd hate to have yet _another_ set of translation functions, and
> another chance of people just getting it wrong either in user space or
> the kernel.
>
> So no. Let's not make another set of flags that has no sane way to
> have type-safety to avoid more confusion.
>
> The new flags that _only_ work with openat2() might be named with a
> prefix/suffix to mark that, but I'm not sure it's a huge deal.
>
>
I agree with the philosophy, but I think it doesn’t apply in this case. Here
are the flags:
O_RDONLY, O_WRONLY, O_RDWR: not even a proper bitmask. The kernel already has
the FMODE_ bits to make this make sense. How about we make the openat2
permission bits consistent with the internal representation and let the O_
permission bits remain as an awful translation. The kernel already translates
like this, and it already sucks.
O_CREAT, O_TMPFILE, O_NOCTTY, O_TRUNC: not modes on the fd at all. These
affect the meaning of open(). Heck, for openat2, NOCTTY should be this default.
O_EXCL: hopelessly overloaded.
O_APPEND, O_DIRECT, O_SYNC, O_DSYNC, O_LARGEFILE, O_NOATIME, O_PATH,
O_NONBLOCK: genuine mode bits
O_CLOEXEC: special because it affects the fd, not the struct file.
Linus, you rejected resolveat() because you wanted a *nice* API that people
would use and that might even be adopted by other OSes. Let’s please not make
openat2() be a giant pile of crap in the name of consistency with open().
open(), frankly, is horrible.