svn commit: r365643 - head/bin/cp

[Kyle Evans]

On Sat, Sep 19, 2020 at 6:19 PM Rick Macklem <rmacklem at uoguelph.ca> wrote:
>
> Alan Somers wrote:
> >On Fri, Sep 11, 2020 at 3:52 PM Rick Macklem <rmacklem at uoguelph.ca<mailto:rmacklem at uoguelph.ca>> wrote:
> >Konstantin Belousov wrote:
> >>On Fri, Sep 11, 2020 at 08:49:36PM +0000, Alan Somers wrote:
> >>> Author: asomers
> >>> Date: Fri Sep 11 20:49:36 2020
> >>> New Revision: 365643
> >>> URL: https://svnweb.freebsd.org/changeset/base/365643
> >>>
> >>> Log:
> >>>   cp: fall back to read/write if copy_file_range fails
> >>>
> >>>   Even though copy_file_range has a file-system agnostic version, it still
> >>>   fails on devfs (perhaps because the file descriptor is non-seekable?) In
> >>>   that case, fallback to old-fashioned read/write. Fixes
> >>>   "cp /dev/null /tmp/null"
> >>
> >>Devices are seekable.
> >>
> >>The reason for EINVAL is that vn_copy_file_range() checks that both in and out
> >>vnodes are VREG.  For devfs, they are VCHR.
> >
> >I coded the syscall to the Linux man page, which states that EINVAL is returned
> >if either fd does not refer to a regular file.
> >Having said that, I do not recall testing the VCHR case under Linux. (ie. It might
> >actually work and the man page turns out to be incorrect?)
> >
> >I will test this case under Linux when I get home next week, rick
> I'll admit I haven't tested this in Linux to see if they do return EINVAL.
>
> >Since there's no standard, I think it's fine for us to support devfs if possible.
> 1 - I think this is a good question for a mailing list like freebsd-current at .
> 2 - I see Linux as the de-facto standard these days and consider POSIX no
>       longer relevant, but that's just mho.
> 3 - For NFSv4.2, the Copy operation will fail for non-regular files, so if you
>       do this, you will need to handle the fall-back to using the generic code.
>       (Should be doable, but you need to be aware of this case.)
>
> Having said the above, it is up to the "collective" and not me and, as such,
> I suggest #1, to see whether others think doing a non-Linux compatible
> version makes sense for FreeBSD?
>

Testing on Debian I seem to get back an EINVAL, but I think it's maybe
a little surprising:

       EXDEV  The files referred to by file_in and file_out are
              not on the same mounted filesystem.

Thanks,

Kyle Evans