Remove rule function

[Gustavo Beltrami Rossi]

Hello,

I'm writing a function that remove rules on the fly on pf , but I'm 
getting some errors. Maybe can someone please help me figure out whats 
going on.

My current anchor "test" have the rules:

# pfctl -a test -sr
pass out quick on ne4 inet proto tcp from 192.168.1.10 port = 10000 to any
pass out quick on ne4 inet from 192.168.1.11 to 192.168.1.11
pass out quick on ne4 inet proto tcp from 192.168.1.10 port = 17688 to 
192.168.1.2 port = 5800 keep state label "ptguard" queue mail
pass out quick on ne4 inet proto tcp from 192.168.1.2 port = 5800 to 
192.168.1.10 port = 17688 keep state label "ptguard" queue mail

I want to remove the rules on this anchor that have the label "ptguard".
I wrote a function to remove the rules:
int rem_pf_rule (void)
{
 struct pfioc_rule rem_rule;
 memset (&rem_rule, 0, sizeof(rem_rule));
 if (ioctl(dev, DIOCGETRULES, &rem_rule)) {
   if (errno == EINVAL)
     rem_rule.nr = 0;
 } else {
     syslog(LOG_ERR, "DIOCGETRULES: %m");
     return (-1);
 }
 while (rem_rule.nr > 0) {
   rem_rule.nr--;
   if (ioctl(dev, DIOCGETRULE, &rem_rule)) {
     syslog(LOG_ERR, "DIOCGETRULE: %m");
     return (-1);
   }
   if (strncmp(rem_rule.rule.label, "ptguard", PF_RULE_LABEL_SIZE) == 0) {
     if (rem_rule.rule.states <= 0) {
       /* get a ticket so we can call DIOCCHANGERULE below */
       rem_rule.action = PF_CHANGE_GET_TICKET;
       if (ioctl(dev, DIOCCHANGERULE, &rem_rule))
         syslog(LOG_ERR, "DIOCCHANGERULE: %m");
       rem_rule.action = PF_CHANGE_REMOVE;
       if (ioctl(dev, DIOCCHANGERULE, &rem_rule))
         syslog(LOG_ERR, "DIOCCHANGERULE: %m");
       if (ioctl(dev, DIOCGETRULES, &rem_rule)) {
         if (errno == EINVAL)
           rem_rule.nr = 0;
         else {
           syslog(LOG_ERR, "DIOCGETRULES: %m");
           return (-1);
         }
       }
     } /* rule.state <= 0 */
   } /* rule.label == ptguard */
 } /* while */
 return (0);
}
But I'm getting an error and I can't figure out what is the problem:

Sep 30 15:59:28 fw ptguard[9116]: DIOCGETRULES: Undefined error: 0

Please someone help me out with this problem,
Thanks in advance,
Gustavo Rossi.