Hi,
Bigsy Bohr wrote:
> From the wodim man page:
>
> In any case, the user running wodim needs read and write access to the
> particular device file on a Linux system.
This is still technical reality with Linux kernels.
> It is recommended to be root or
> install the application as suid-root, because certain versions of Linux
> (kernel) limit the set of SCSI commands allowed for non-root users.
According to strace and the option -V of wodim, no SCSI commands were
emitted by the failed run of wodim --devices .
Yes, there are SCSI commands which ioctl(SG_IO) will pass to the
drive only if the emitting process has a superuser-like capability.
But none of the commands related to CD burning is among them.
libburn never encountered the need for superuser powers, beyond the
demand for rw-permissions with the device file.
> Even if
> usage without root identity is possible in many cases, some device drivers
> still may fail, show unexplainable problems and generally the problems
> become harder to debug.
I think this is the result of similar head scratching by the wodim
maintainers as we experience right now.
> The risk for buffer-underruns is also increased. See the
> PROCESS SCHEDULING PRIORITY section below for more details.
Buffer underruns should really be history. man wodim says:
driveropts=option list
...
burnfree
Turn the support for Buffer Underrun Free writing on.
...
This option is deprecated and is mentioned here for docu‐
mentation purposes only. The BURN-Free feature is enabled
by default if the drive supports it.
My Yamaha CD burners from the late 1990s did not have it. My LITE-ON
from 2000 had it. All DVD and BD burners are supposed to have it.
Bigsy Bohr wrote:
> In light of this, it seems possible the newer kernel in Trixie is less
> lenient than older versions when running wodim as an unprivileged user.
In some way this is supposed to be the problem.
But i fail to find the suspicious calls from the strace output in
the source of wodim.
No prctl() calls, no PR_CAPBSET_READ, no openat() calls:
https://codesearch.debian.net/search?q=package%3Acdrkit+prctl
https://codesearch.debian.net/search?q=package%3Acdrkit+PR_CAPBSET_READ&literal=0
https://codesearch.debian.net/search?q=package%3Acdrkit+openat&literal=0
Calls to access() only in genisoimage sources:
https://codesearch.debian.net/search?q=package%3Acdrkit+access\%28&literal=0
So these straced calls obviously are triggered by other calls which
wodim makes.
Have a nice day :)
Thomas
