* Christian Brauner:

quoted

Solaris has an fdwalk function:

  <https://docs.oracle.com/cd/E88353_01/html/E37843/closefrom-3c.html>

So a different way to implement this would expose a nextfd system call

Meh. If nextfd() then I would like it to be able to:
- get the nextfd(fd) >= fd
- get highest open fd e.g. nextfd(-1)

The highest open descriptor isn't istering for fdwalk because nextfd
would just fail.

But then I wonder if nextfd() needs to be a syscall and isn't just
either:
fcntl(fd, F_GET_NEXT)?
or
prctl(PR_GET_NEXT)?

I think the fcntl route is a bit iffy because you might need it to get
the *first* valid descriptor.

quoted

to userspace, so that we can use that to implement both fdwalk and
closefrom.  But maybe fdwalk is just too obscure, given the existence of
/proc.

Yeah we probably don't need fdwalk.

Agreed.  Just wanted to bring it up for completeness.  I certainly don't
want to derail the implementation of close_range.

Thanks,
Florian