001  #!/usr/bin/perl
002  #It's already too late to do that check here, but at least try to print a
003  #warning
004  if ($> != $<)
005  {
006    print "Must not run with Set-UID bit set\n";
007    exit;
008  }

033  #We need to be root at startup so we can bind to the ident port.
034  if ($< != 0)
035  {
036    print "Need to be root to bind to the ident port\n";
037    exit;
038  }
039  chdir("/") or die "Can not change working directory";

057    if ($file =~ /^[^-'][^']*\.hash$/)
058    {
059      $usefile=$file;
060    }

066  open(STR1,"/usr/bin/strings /usr/lib/ispell/'$usefile'|")||die "Can't start strings";

152  ($pnam,$dummy,$myuid,$mygid)=getpwnam("nobody");

158  #Just in case  O_NOFOLLOW is not supported we double check.
159  if (-l "/tmp/rident.pid") {

161     exit;
162  } elsif (sysopen(PID,"/tmp/rident.pid",O_RDONLY | O_NOFOLLOW)) {
163    $oldpid = 0;
164    ($pfuid,$pfgid) = (stat(PID))[4,5] or die "PANIC: Can not stat open pidfile";
165    unless ($pfuid == $myuid || $pfgid == $mygid)
166    {

168      exit;
169    } else {
170      #See if the file was already written.
171      seek(PID,0,SEEK_END);
172      $size=tell(PID);
173      seek(PID,0,SEEK_SET);

175      if ($size > 0 && $size < 100) {

177  	  sysread(PID,$oldpid,$size,0);
178  	  chomp $oldpid;
179  	  unless ($oldpid =~ /^\d+$/)
180  	  {

182  	    exit;
183  	  }
184  	  $oldpid +=0;
185      } else {
186  	  &dprint("* PID file is corrupt\n");
187  	  exit;
188      }
189    }
190    close(PID);
191    #Now let's test if the found pid is really our old instance.
192    $killit=0;
193    if ($oldpid)
194    {

196      open(PS,"/bin/ps -p '$oldpid'|");
197      $killit=0;
198      while (<PS>)
199      {
200         if (/\bridentd\.pl\b/)
201         {
202           $killit=$oldpid;
203         }
204      }
205      unless ($killit)
206      {
207        &dprint("* pid file apears to be old\n");
208      } else {
209        #We need to kill the old process, but we are root and thus to powerfull.
210        $tpid=fork();
211        unless (defined($tpid)) {
212          print "ERR: Forking error\n";
213          exit;
214        }
215        if ($tpid) {
216          #The parent remains root and must wait for the child process.
217          &dprint("* Started background process to kill old instance safely\n");
218          waitpid($tpid,0);
219          &dprint("* Background process finished.\n");
220          sleep(1);
221        } else {
222          unless ($)=$mygid) {print "Cleanup Unable to set group ID to $mygid\n";exit;}
223          unless ($>=$myuid) {print "Cleanup Unable to set user ID to $myuid\n";exit;}
224          kill(9,$killit);
225          exit;
226        }
227      }
228    }
229  }

237  unlink("/tmp/rident.pid");

241  unless (sysopen(PID,"/tmp/rident.pid",O_RDWR | O_CREAT | O_EXCL, 0600)) {
242    print "PANIC: Could not create the pid file /tmp/rident.pid $! $?\n";
243    exit;
244  }

246  $pid=fork();

252  if ($pid)
253  {
254    # parent
255    unless (syswrite(PID,"$pid\n",length("$pid\n"))) {

257      close(PID);
258      kill(9,$pid);
259    }
260    exit;
261  }