Re: [PATCH RESEND v14 2/6] namei: LOOKUP_IN_ROOT: chroot-like path resolution

On 2019-10-27, Linus Torvalds torvalds@linux-foundation.org wrote:

On Sat, Oct 26, 2019 at 2:58 PM Aleksa Sarai cyphar@cyphar.com wrote:

...

•   /* LOOKUP_IN_ROOT treats absolute paths as being relative-to-dirfd. */
  

•   if (flags & LOOKUP_IN_ROOT)
  

•           while (*s == '/')
  

•                   s++;
  

•   /* Figure out the starting path and root (if needed). */
    if (*s == '/') {
            error = nd_jump_root(nd);
  

So I'm still hung up on this.

I guess I can't help it, but I look at the above, and it makes me go "whoever wrote those tests wasn't thinking".

It just annoys me how it tests for '/' completely unnecessarily.

If LOOKUP_IN_ROOT is true, we know the subsequent test for '/' is not going to match, because we just removed it. So I look at that code and go "that code is doing stupid things".

Okay, fair enough.

That's why I suggested moving the LOOKUP_IN_ROOT check inside the '/' test.

Alternatively, just make the logic be

    if (flags & LOOKUP_IN_ROOT) {
           .. remove '/'s ...
    } else if (*s == '/') {
            .. handl;e root ..

and remove the next "else" clause

I've gone with the latter since I think it reads better.