Re: warning: `growisofs' uses 32-bit capabilities (legacy support in use)

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

Jeffrey Walton wrote:
> I'm testing a new dual layer DVD reader/writer. The write failed (a
> separate issue),

If it has an interesting cause, then i would like to learn about it
(with my libburn hat on).


>     capability: warning: `growisofs' uses 32-bit capabilities (legacy support in use)

I am staring at growisofs.c where syscall(SYS_capset,&h,&d) is issued.
First of all i don't understand why growisofs is setting CAP_SYS_RAWIO
at all. I never experienced the need for this in libburn.
man 7 capabilities says:
       CAP_SYS_RAWIO
              ...
              * perform various SCSI device commands;
              ...
but those which are necessary for operating optical drives work fine
without the need for CAP_SYS_RAWIO.
Probably Andy Polyakov just wants to get rid of all possibly set
capabilities except CAP_SYS_RAWIO.
I don't see any "Current:" capabilities set for a normal user in the
output of
  /sbin/capsh --print

Next i wonder why growisofs uses syscall(SYS_capset,...) instead of
capset(2) or cap_set_proc(3) or capsetp(3).


> According to http://fy.chalmers.se/~appro/linux/DVD+RW/,
> cdwrite@other.debian.org is the place for discussions about growisofs.

Andy Polyakov did not show up here since years. If the problem would
hamper burning, i would try to propose a workaround. But since i don't
even understand the motivation of the capabilities manipulation, i
refrain from a proposal.

(One could make experiments whether that code piece is needed at all.)


> It would be nice to see someone with knowledge of the issue to fix it
> once and for all nowadays.

Besides my lack of understanding with that part of growisofs, there is the
problem that a fix would have to be brought to
  http://fy.chalmers.se/~appro/linux/DVD+RW/
so that all distros can get it.


Have a nice day :)

Thomas