bug#33105: cups Can't create temporary file or stopped "Filter failed"

bug#33105: cups Can't create temporary file or stopped "Filter failed"

[Oleg Pykhalov]

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Hello Guix,

I've spotted a bug in CUPS service “Can't create temporary file”.  If I
gave ‘765’ permissions to ‘/var/spool/cups/tmp/’ directory then an error
is “stopped "Filter failed"”.  ‘777’ for /var/spool/cups/tmp/ is
required to print a test page via CUPS WEB interface.


I read gnu/services/cups.scm and found that the /var/spool/cups/
directory should be owned by ‘lp’ user:
--8<---------------cut here---------------start------------->8---
(define %cups-activation
  ;; Activation gexp.
  (with-imported-modules '((guix build utils))
    #~(begin
        (use-modules (guix build utils))
        (define (mkdir-p/perms directory owner perms)
          (mkdir-p directory)
          (chown "/var/run/cups" (passwd:uid owner) (passwd:gid owner))
          ;; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
          (chmod directory perms))
        ;; …
        (let ((user (getpwnam "lp")))
          ;; …
          (mkdir-p/perms "/var/spool/cups/tmp" user #o755) ; <----------
          ;; …
          ))))
--8<---------------cut here---------------end--------------->8---


Maybe we should make /var/spool/cups/tmp directory owned by ‘lp’ user,
too?  WDYT?

Test page was printed successfully with:
--8<---------------cut here---------------start------------->8---
$ sudo ls -ld /var/spool/cups/tmp
drwxr-xr-x 2 lp lp 4096 Oct 20 21:20 /var/spool/cups/tmp
--8<---------------cut here---------------end--------------->8---


From cups-files.conf(5) man page:

TempDir directory
     Specifies the  directory  where  short-term  temporary  files  are
     stored.  The default is "/var/spool/cups/tmp".

User username
     Specifies  the  user name or ID that is used when running external
     programs.  The default is "lp".


Oleg.

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bug#33105: cups Can't create temporary file or stopped "Filter failed"

[Efraim Flashner]

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On Sat, Oct 20, 2018 at 09:36:57PM +0300, Oleg Pykhalov wrote:
> Hello Guix,
> 
> I've spotted a bug in CUPS service “Can't create temporary file”.  If I
> gave ‘765’ permissions to ‘/var/spool/cups/tmp/’ directory then an error
> is “stopped "Filter failed"”.  ‘777’ for /var/spool/cups/tmp/ is
> required to print a test page via CUPS WEB interface.
> 
> 
> I read gnu/services/cups.scm and found that the /var/spool/cups/
> directory should be owned by ‘lp’ user:
> --8<---------------cut here---------------start------------->8---
> (define %cups-activation
>   ;; Activation gexp.
>   (with-imported-modules '((guix build utils))
>     #~(begin
>         (use-modules (guix build utils))
>         (define (mkdir-p/perms directory owner perms)
>           (mkdir-p directory)
>           (chown "/var/run/cups" (passwd:uid owner) (passwd:gid owner))
>           ;; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>           (chmod directory perms))
>         ;; …
>         (let ((user (getpwnam "lp")))
>           ;; …
>           (mkdir-p/perms "/var/spool/cups/tmp" user #o755) ; <----------
>           ;; …
>           ))))
> --8<---------------cut here---------------end--------------->8---
> 
> 
> Maybe we should make /var/spool/cups/tmp directory owned by ‘lp’ user,
> too?  WDYT?

currently /var/spool/cups is root:lp, my first thought is to change it
to lp:lpadmin (not sure where I got lpadmin from) and make it 775.

> 
> Test page was printed successfully with:
> --8<---------------cut here---------------start------------->8---
> $ sudo ls -ld /var/spool/cups/tmp
> drwxr-xr-x 2 lp lp 4096 Oct 20 21:20 /var/spool/cups/tmp
> --8<---------------cut here---------------end--------------->8---
> 
> 
> From cups-files.conf(5) man page:
> 
> TempDir directory
>      Specifies the  directory  where  short-term  temporary  files  are
>      stored.  The default is "/var/spool/cups/tmp".
> 
> User username
>      Specifies  the  user name or ID that is used when running external
>      programs.  The default is "lp".
> 
> 
> Oleg.



-- 
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bug#33105: cups Can't create temporary file or stopped "Filter failed"

[Ludovic Courtès]

Hi Oleg,

Oleg Pykhalov <go.wigust@gmail.com> skribis:

> I read gnu/services/cups.scm and found that the /var/spool/cups/
> directory should be owned by ‘lp’ user:
>
> (define %cups-activation
>   ;; Activation gexp.
>   (with-imported-modules '((guix build utils))
>     #~(begin
>         (use-modules (guix build utils))
>         (define (mkdir-p/perms directory owner perms)
>           (mkdir-p directory)
>           (chown "/var/run/cups" (passwd:uid owner) (passwd:gid owner))
>           ;; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>           (chmod directory perms))
>         ;; …
>         (let ((user (getpwnam "lp")))
>           ;; …
>           (mkdir-p/perms "/var/spool/cups/tmp" user #o755) ; <----------
>           ;; …
>           ))))
>
>
>
> Maybe we should make /var/spool/cups/tmp directory owned by ‘lp’ user,
> too?  WDYT?
>
> Test page was printed successfully with:
>
> $ sudo ls -ld /var/spool/cups/tmp
> drwxr-xr-x 2 lp lp 4096 Oct 20 21:20 /var/spool/cups/tmp

I don’t know the answer :-), but from what you’re saying, it looks like
making /var/spool/cups/tmp ‘lp’-owned is the right thing.

If it works for you, I guess you can go ahead!

Ludo’.