Hi Christian,
Thanks for confirming that behavior. Seems reasonable.
I was wondering...
If this call is equivalent to unshare(2)+{close(2) in a loop},
shouldn't it fail for the same reasons those syscalls can fail?
What about the following errors?:
>From unshare(2):
EPERM The calling process did not have the required privi‐
leges for this operation.
>From close(2):
EBADF fd isn't a valid open file descriptor.
OK, this one can't happen with the current code.
Let's say there are fds 1 to 10, and you call 'close_range(20,30,0)'.
It's a no-op (although it will still unshare if the flag is set).
But souldn't it fail with EBADF?
EINTR The close() call was interrupted by a signal; see sig‐
nal(7).
EIO An I/O error occurred.
ENOSPC, EDQUOT
On NFS, these errors are not normally reported against
the first write which exceeds the available storage
space, but instead against a subsequent write(2),
fsync(2), or close().
Thanks,
Alex
On 12/9/20 11:56 AM, Christian Brauner wrote:
> On Wed, Dec 09, 2020 at 11:44:22AM +0100, Alejandro Colomar (man-pages) wrote:
>> Hey Christian,
>>
>> I have a question for you below.
>>
>> Thanks,
>
> Hey Alex,
>
> Sure!
[...]
>>
>> AFAICS after reading the code, if the unsharing fails,
>> it will not close any file descriptors (please correct me if I'm wrong).
>>
>> Just wanted to be sure that it was the intended behavior with you,
>> and if so, it would be good to document it in the page.
>
> Yes, this is intended because if the unshare fails we haven't yet
> actually started closing anything so we're before the point of no
> return where we ignore failures. So we can let userspace decide whether
> they want to retry without CLOSE_RANGE_UNSHARE.
>
> Christian
>
--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es
