<?php
function custom_form_alter($form_id, &$form) {
  $arg0 = '';
  $nid = '';
  $arg0 = arg(0);
  if ($arg0 == 'node') {
    $nid = arg(1);
  }
  else if ($arg0 == 'comment') {
    $nid = arg(1);
  }
  if ($arg0 != '' && $nid != '' && $form_id == 'comment_form') {
    $case_node = node_load(array('nid' => $nid));
    if (!custom_user_oneof_owner($case_node->assign_to, $case_node->uid, $case_node->pid)) {
      return drupal_access_denied();
    }
  }
}
 
function custom_nodeapi(&$node, $op, $a3 = NULL, $a4 = NULL) {
  switch ($op) {
    case 'view':
      if ($node->case_status_id == 6 && !custom_user_oneof_owner($node->assign_to, $node->uid, $node->pid) && $node->type == 'casetracker_basic_case') {
        return drupal_access_denied();
      }
      break;
  }
}
 
function custom_user_oneof_owner($aid, $cuid, $pid) {
  global $user;
  $project_node = node_load(array('nid' => $pid));
 
  if ($user->uid == $project_node->uid || $user->uid == $cuid || $user->uid == $aid || $user->uid == 1) {
    return true;
  }
  else {
    return false;
  }
}