C11 threads ABI questions - enum values

[Rich Felker]

On Fri, Oct 03, 2014 at 08:39:10PM +0200, Christoph Hellwig wrote:
> On Fri, Oct 03, 2014 at 11:32:48AM -0400, Rich Felker wrote:
> > Indeed, they need to be reserved on the kernel side, and during the
> > discussion on linux-api, almost everybody seemed to be failing to
> > understand why this is needed... :(
> 
> At least of O_SEARCH and O_EXEC I strongly disagreed with the idea that
> they should be implementated in userspace and still do.

I do to, but for now it's the only way possible on Linux. For instance
it seems to be impossible to implement the POSIX rule (at least as I
understand it) that, when using an O_SEARCH or O_EXEC fd, the status
of the +x mode bit at open-time, rather than at the time of the
operation, dictates success or failure. There are a few other corner
cases where you want O_PATH and O_SEARCH/O_EXEC to behave differently,
too: for example, O_PATH|O_NOFOLLOW should open the symlink, while
O_SEARCH|O_NOFOLLOW or O_EXEC|O_NOFOLLOW should fail if the target is
a symlink.

Rich