lpr: unable to create temporary file / was: Re: [Xprint] Xprint 009.001 test canidate builds...

[Aleksander Adamowski]

Roland Mainz wrote:

>I still cannot reproduce the problem.. nor did David. And I've spend a
>whole day at SuSE last week and we weren't able to reproduce the problem
>there either... ;-(((
>We need something like "truss" or "strace", watch Xprt+lpr (e.g. all
>child processes launched by Xprt) and dump everything to a log... maybe
>that gives a hint what's going wrong...
>  
>
On Mandrake Cooker, I've successfully isolated two issues.

1) during system startup, when the xprint initscript is executed, Xprt 
cannot contact the cups server because the cupsd has'nt managed to start 
yet. Startup scripts of CUPS and XPrint have dangerously close priorities:

# ls /etc/rc5.d/ | grep ^S  | egrep "(xprint|cups)" | sort
S-1xprint@
S60cups@
S61xprint@

I propose to lower the default start priority level of xprint init 
script, from 61 to 50 or even less, so it stars up earlier.
CUPS starts with priority 60 on Mandrake and 55 on Fedora Core 1. Or 
even better, XPrint could retry connecting to the CUPS server in a 
couple of seconds instead of failing instantly.

For example, Xprt could try to connect 3 times, with 5 seconds long 
pause between 1st and 2nd try, and 30 seconds pause between 2nd and 3rd try.

This issue has been causing the syslog message "Xprt_33: lpstat: Unable 
to connect to server: Connection refused". Please, make this message 
more descriptive - it should contain the address of the CUPS server that 
is contacted.

2) I did a "strace -f" of Xprt process and have discovered that XPrint 
first changes its uid to the user that has submitted the job for 
printing and executes lpr:
[pid  7402] setuid32(501)               = 0
[pid  7402] execve("/usr/bin/lpr", ["/usr/bin/lpr", "-P", 
"unix_17p_HPLJ2100", "-#1", "-T", "PS printing testcase"], [/* 55 vars 
*/]) = 0

, and then lpr fails because it tries to write to a temporary directory 
owned by root:
[pid  7402] open("/root/tmp/40f3f94f5c478", O_RDWR|O_CREAT|O_EXCL, 0600) 
= -1 EACCES (Permission denied)
[pid  7402] write(2, "lpr: unable to create temporary "..., 38) = 38

Seems that XPrint executes lpr with the environment configured from the 
root user's settings (I've started xprint using the /etc/init.d/xprint 
restart). I have the root user's TMP, TMPDIR and SCREENDIR variable set 
to /root/tmp. Possiblt the xprint startup script or Xprt binary itself 
can sanitize its environment, especially any variables that can affect 
the local printing system's tools?

The syslog message here is generated by CUPS's lpr, so CUPS (not XPrint) 
guys need to make this error message more descriptive.

-- 
Best Regards,
  Aleksander Adamowski
    GG#: 274614
    ICQ UIN: 19780575 
  http://olo.ab.altkom.pl