[cups.general] Odd behavior with CUPS 1.2.x and the way backends are executed

[Dominik L. Borkowski]

Hello,

Long story short, our installation of the PDF Distiller script has quit after 
an upgrade of CUPS from 1.1.23 to 1.2.7. After some debugging, it seems to be 
the problem is that CUPS 1.2.x no longer runs our backend scripts as root, 
which means that the script cannot copy/chown files properly.

Our cupsd.conf has not changed, and it's currently set up with the following:
--
User lp
Group sys
--

Here is a sample output of the following line in the pdf backend script:

echo    " Vitals     : USER=$USER, UID=$UID, GID=$GID, id reports:" `id` 
>>$LOGFILE


CUPS 1.2.7:
 Vitals     : USER=root, UID=4, GID=, id reports: uid=4(lp) gid=3(sys) 

CUPS 1.1.23:
 Vitals     : USER=root, UID=0, GID=, id reports: uid=0(root) gid=0(root) 
groups=3(sys)

In theory, CUPS 1.2.7 does the right thing - it uses the defined User/Group 
settings. That would be fine, if they actually worked as expected. However, 
it seems that SystemGroup affects what uid reports, and we can't ever set uid 
to 0.

scenario #1:  - correct
User lp
Group sys
SystemGroup printadm
Vitals     : USER=root, UID=4, GID=, id reports: uid=4(lp) gid=3(sys) groups=3
(sys)

scenario #2: - incorrect
User root
Group sys
SystemGroup printadm
Vitals     : USER=root, UID=4, GID=, id reports: uid=4(lp) gid=3(sys) groups=3
(sys)

scenario #3: - correct
User lp
Group lp
SystemGroup printadm
 Vitals     : USER=root, UID=4, GID=, id reports: uid=4(lp) gid=7(lp) groups=7
(lp)

scenario #4: - incorrect
User root
Group lp
SystemGroup printadm
 Vitals     : USER=root, UID=4, GID=, id reports: uid=4(lp) gid=7(lp) groups=7
(lp)

scenario #5: -  what? sys gid is 3, not 98
User lp
Group sys
SystemGroup printadm sys
Vitals     : USER=root, UID=4, GID=, id reports: uid=4(lp) gid=98(nobody) 
groups=98(nobody)

scenario #6: -  now that's inconsistent with scenario #5
User lp
Group sys
SystemGroup printadm root
 Vitals     : USER=root, UID=4, GID=, id reports: uid=4(lp) gid=3(sys) 
groups=3(sys)


Any thoughts? If it's documented in the Changelog, I have not been able to 
find it. I'd appreciate any input.

sincerely,
-- 
Dominik L. Borkowski - Senior Systems Administrator
Virginia Bioinformatics Institute - www.vbi.vt.edu