PHP calls C calls Perl calls Shell

[Anon]

I have a PHP system that runs special Kermit programs to communicate with phone systems. For some reason (apparently after upgrading from version 3.0.12 to 4.0.6) I can no longer execute the system calls from within Perl within PHP.

The PHP script calls a C program that changes the UID to a special UID to run the Perl script. The Perl script then does some pre processing. Included in the preprocessing is a call to '/bin/ps' with the Perl backtick operator. This is where the Perl program dies when run from within PHP. I can run the Perl program from the command line as the special user without any trouble. The first system of exec or backtick within the Perl program causes the Perl program to exit.

Thanks,
Andrej Andrejko

[Anon]

Sounds very interesting! Can you show some sample code (my brain works when I see code, not words :-).

Maybe just tell us the error messages (or the output, if any) if your code is proprietary.

thanks,
-sridhar

[Anon]

Here is the php script code:

if($action == "manualbackup")
{
echo "<pre>\n";
if(system(EscapeShellCmd("/wwwi/app/mitelbkp/perform_backup_suid $id")))
{

}
else
{
echo "\nSystem command failed";
}
echo "</pre>\n";
exit;
}

The source for perform_backup_suid looks like:

#define REAL_PATH "/wwwi/app/mitelbkp/perform_backup"
main(ac, av)
char **av;
{
execv(REAL_PATH, av);
}

perform_backup is a Perl script. Ther Perl script fails here:

$kcount = 10000;
while($kcount > $kermit_limit)
{
#system("ls");

  print("checking number of backups already in progress...");
  # count the number of running kermits
  $kcount = `(/bin/ps auxw | /bin/grep ermit | /bin/grep mitelbkp | /bin/gre

p -v grep | /usr/bin/wc --lines) 2>&1`;
if($? == 0)
{
print("done\n");
}
else
{
print("error\n");
}
chop $kcount;
$kcount =~ /([0-9]+)/;
$kcount = $1;
print "too many running kermits ($kcount already running)\n";
sleep 3;
}

If you uncomment the system("ls") line then the perl script will die at that line. There is no error message in the error_log apache log file.

Erik