@seb are you helping on this?
** Changed in: canonical-devices-system-image
Status: New => Confirmed
** Changed in: canonical-devices-system-image
Assignee: (unassigned) => Sebastien Bacher (seb128)
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https://bugs.launchpad.net/bugs/1509423
Title:
cupsd on the phone is unable to run sub processes, they all cause
"Command not found"
Status in Canonical System Image:
Confirmed
Status in cups package in Ubuntu:
New
Bug description:
I have started to test the printing stack of Ubuntu on the phone.
I have a Nexus 4 now to test the printing stack on the phone.
First I have updated the USB-connected phone to the development branch
of the OS via
ubuntu-device-flash touch --channel=devel
with the phone booted into Ubuntu and the screen unlocked.
After the reboot of the phone I have run
phablet-config writable-image
to be able to install packages with apt-get and entered a shell on the
phone via
phablet-shell
In the shell I first installed a level-1 printing stack (See
https://blueprints.launchpad.net/ubuntu/+spec/client-1305-printing-
stack-with-mobile-in-mind for the levels):
sudo apt-get install cups-daemon cups-browsed avahi-daemon
This makes the following new packages getting installed:
The following NEW packages will be installed:
avahi-daemon bc bind9-host cups-browsed cups-daemon libavahi-core7
libavahi-glib1 libbind9-90 libcupsmime1 libdaemon0 libdns100 libgeoip1
libisc95 libisccc90 libisccfg90 liblwres90 libpaper1 ssl-cert
0 upgraded, 18 newly installed, 0 to remove and 0 not upgraded.
Need to get 1,502 kB of archives.
After this operation, 4,698 kB of additional disk space will be used.
The installation was hanging on the postinst of CUPS, so I had to open
a new shell in another terminal and kill the postinst for the
installation process to finish.
sudo apt-get install -f
has re-run the CUPS postinst and this time it finished.
As the phone apps do not yet have a print dialog I needed a print
client on the phone, and also some tools for developing and debugging.
So I have installed cups-client, giving me command line printing and
print admin commands, as lp, lpstat, lpinfo, lpadmin, ...:
sudo apt-get install cups-client
[...]
The following NEW packages will be installed:
cups-client cups-common libcupsfilters1 libcupsimage2
0 upgraded, 4 newly installed, 0 to remove and 0 not upgraded.
Need to get 368 kB of archives.
After this operation, 2,810 kB of additional disk space will be used.
PID 1 on the phone is still Upstart, Upstart is configured to start
CUPS on-demand, via
/etc/init/cups.override
cups.override needs to be corrected, as cupsd does not support the
"-x" option any more, so I have removed the "-x 30" from the cupsd
command line. Now cupsd starts when running commands like
lpstat -r
lpstat -v
...
After that I did
sudo start cups-browsed
to start cups-browsed to get the queues from remote CUPS servers
locally available (level 1 printing stack).
lpstat -v
shows my printers shared on remote CUPS servers now.
Note that CUPS admin tasks need "sudo" as the "phablet" user is not in
the "lpadmin" group.
For the printing tests I do the CUPS logging (in
/var/log/cups/error_log) in debug mode, running
sudo cupsctl --debug-logging
sudo cupsctl
shows my settings.
Now I print via
lp -d printer ~/.bashrc
CUPS is now supposed to send the job via IPP (Internet Printing
Protocol) to the remote CUPS server where the printer is actually
connected to. This it does using a backend, a small helper program, in
our case /usr/lib/cups/backend/ipps.
Printing does not work yet:
1. CUPS reports exit status 127 on the ipps backend call ("command not
found", the fact that in error_log you see "file too large" is a CUPS
bug, exit status 127 is "command not found"), but the backend is
called with its full path, the backend is actually present and
executable, no libs missing (checked with "ldd"), the backend works
directly called from the command line.
2. No name resolution in the local network (avahi problem? avahi-
daemon is running). Manual call of the backend only works if the host
name in the device URI is replaced by the corresponding IP address.
So following command prints:
DEVICE_URI=ipps://192.168.0.11:631/printers/printer
CONTENT_TYPE=text/plain /usr/lib/cups/backend/ipps 1 1 1 1 ""
~/.bashrc
Also
sudo DEVICE_URI=ipps://192.168.0.11:631/printers/printer
CONTENT_TYPE=text/plain /usr/lib/cups/backend/ipps 1 1 1 1 ""
~/.bashrc
prints.
To overcome the host name resolution problem I have modified cups-
browsed to create the local queues with IP addresses instead of host
names in the device URIs. So the remeining problem is (1), for which I
have opened this bug report.
The problem is most probably no caused by AppArmor, as I do not see
appropriate "audit" messages in /var/log/syslog and I have done
aa-complain cupsd
to have cupsd in complain mode and not in enforce mode.
As both the ipp/ipps backend and another backend which is a shell
script do not start and give exit status 127, it seems for me that
make cupsd running a command line "strace ipp ..." will also end up in
nothing being executed.
So I tried
strace cupsd -f > log 2>&1 &
and afterwards ran a job
lp -d canon-colour .bashrc
After some time I canceled the job (as it did not get executed due to
the known problem) and stopped CUPS.
The resulting file "log" is attached. The problem happened on
14/Oct/2015:14:55:31, you can search for "14/Oct/2015:14:55:31" in the
log, then for "backend/ipp".
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