Bug#588249: libproc-processtable-perl: length of fname field in ProcessTable is insufficient

[Salvatore Bonaccorso]

severity 588249 wishlist
thanks

Hi 

On Tue, Jul 06, 2010 at 03:41:18PM +0200, J G Miller wrote:
> Package: libproc-processtable-perl
> Version: 0.45-1
> Severity: normal
> 
> Whilst setting up mon (monitoring system) with the ps.monitor script
> which uses Proc::ProcessTable to get a list of the processes on the
> system, I discovered that processes with very long names are being
> truncated, thus causing a false alert in mon.
> 
> Debugging the relevant part of the ps.monitor script --
> 
>   use Proc::ProcessTable;
> 
>   my $process_table = new Proc::ProcessTable('cache_ttys' => 0 );
> 
>   foreach $process ( @{$process_table->table} )
>   {
>    printf ("Examining       ->%s<-\n",               $process->cmndline);
>    printf ("+++ Checking if ->%s<- is required\n\n", $process->fname);
>   }
> 
> reveals that process name in fname is truncated at 15 characters
> 
>    Examining       ->transmission-daemon<-
>    +++ Checking if ->transmission-da<- is required
> 
> Thus it is evident that the width of fname should be increased
> from 16 to 24 if possible.
> 
> Obviously in its current form, checking of process names greater
> than 15 characters will lead to false alarms in mon, and problems
> in other packages which use this functionality.

I think this is indeed not possible, but a comment from someone else
is appreciated to confirm that in case:

This seems to be a limitiation in linux itself, first in os/Linux.c we
have:

    /* scan in pid, and the command, in linux the command is a max of 15 chars
     * plus a terminating NULL byte; prs->comm will be NULL terminated since
     * that area of memory is all zerored out when prs is allocated */
    if (sscanf(stat_text, "%d (%15c", &prs->pid, prs->comm) != 2)
        goto done;

In the Linux kernel itself, we have

include/linux/elfcore.h:        char    pr_fname[16];      /* filename of executable */

So probably there is no work around this if you use fname.

So as it is not really caused by fname in Proc::ProcessTable I think
this is more like a wishlist, as it is by 'limitation' in the linux
kernel.

Comments?

Bests
Salvatore
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