farmOS/modules/farm/farm_access/farm_access.module

<?php
/**
 * @file
 * Farm Access module.
 */

/**
 * Implements hook_hook_info().
 */
function farm_access_hook_info() {
  $hooks['farm_access_roles'] = array(
    'group' => 'farm_access',
  );
  $hooks['farm_access_perms'] = array(
    'group' => 'farm_access',
  );
  $hooks['farm_access_perms_alter'] = array(
    'group' => 'farm_access',
  );
  return $hooks;
}

/**
 * Load a list of farm roles.
 *
 * @return array
 *   Returns an array of farm role names.
 */
function farm_access_roles() {

  // Invoke hook_farm_access_roles() to get a list of roles.
  return module_invoke_all('farm_access_roles');
}

/**
 * Create farm roles.
 */
function farm_access_roles_create() {

  // Get a list of farm roles.
  $roles = farm_access_roles();

  // Iterate through the roles.
  foreach ($roles as $name) {

    // Load the role by name.
    $role = user_role_load_by_name($name);

    // If the role doesn't exist, create it.
    if (empty($role)) {
      $role = new stdClass();
      $role->name = $name;
      user_role_save($role);
    }
  }
}

/**
 * Synchronize all available farm permissions farm roles.
 */
function farm_access_sync_perms() {

  // Get a list of farm roles.
  $roles = farm_access_roles();

  // Iterate through the available roles.
  foreach ($roles as $role) {

    // Compare current perms to available perms.
    $compare = farm_access_compare_perms($role);

    // Start with a blank array of changes.
    $changes = array();

    // Add perms.
    if (!empty($compare['add'])) {
      foreach ($compare['add'] as $perm) {
        $changes[$perm] = TRUE;
      }
    }

    // Remove perms.
    if (!empty($compare['remove'])) {
      foreach ($compare['remove'] as $perm) {
        $changes[$perm] = FALSE;
      }
    }

    // If there are changes to be made...
    if (!empty($changes)) {

      // Load the role.
      $role = user_role_load_by_name($role);

      // If the role does not exist, bail.
      if (empty($role)) {
        return;
      }

      // Apply the changes.
      user_role_change_permissions($role->rid, $changes);
    }
  }
}

/**
 * Gets a list of all available farm permissions.
 *
 * @param string $role
 *    A role name to get current permissions for.
 *
 * @return array
 *   Returns an array of permission strings.
 */
function farm_access_available_perms($role) {

  // Load the permissions provided by this module on behalf of others.
  module_load_include('inc', 'farm_access', 'farm_access.modules');

  // Invoke hook_farm_access_perms() to allow modules to provide permissions.
  $perms = module_invoke_all('farm_access_perms', $role);

  // Unset any that don't exist.
  // This can be an issue with Taxonomies provided by Features.
  $permissions_modules = user_permission_get_modules();
  foreach ($perms as $key => $perm) {
    if (empty($permissions_modules[$perm])) {
      unset($perms[$key]);
    }
  }

  // Allow other modules to alter the permissions for this role.
  drupal_alter('farm_access_perms', $role, $perms);

  // Return them.
  return $perms;
}

/**
 * Gets a list of the permissions currently assigned to farm roles.
 *
 * @param string $role
 *   A role name to get current permissions for.
 *
 * @return array
 *   Returns an array of permission strings.
 */
function farm_access_current_perms($role) {

  // Load the role.
  $role = user_role_load_by_name($role);

  // If the role does not exist, bail.
  if (empty($role)) {
    return array();
  }

  // Load the permissions that are currently assigned to the role.
  $perms = user_role_permissions(array($role->rid => $role->name));

  // Return the permissions for this role, as an array of strings.
  return array_keys($perms[$role->rid]);
}

/**
 * Compares available permissions to actual permissions.
 *
 * @param string $role
 *   A role name to get current permissions for.
 *
 * @return array
 *   Returns an array with two sub-arrays:
 *     'add': a list of permission strings that should be added
 *     'remove': a list of permission strings that should be removed
 */
function farm_access_compare_perms($role) {

  // Get the available perms.
  $available_perms = farm_access_available_perms($role);

  // Get the currently applied perms.
  $current_perms = farm_access_current_perms($role);

  // Determine which perms should be added.
  $compare['add'] = array_diff($available_perms, $current_perms);

  // Determine which perms should be removed.
  $compare['remove'] = array_diff($current_perms, $available_perms);

  // Return the comparison.
  return $compare;
}

/**
 * Generate permission lists for farm entities.
 *
 * This is a helper function to make the task of generating permission lists
 * easier.
 *
 * @param array $types
 *   An array of entity types/bundles to generate permissions for. Example:
 *     $types = array(
 *       'taxonomy' => array(
 *         'farm_areas',
 *       ),
 *     );
 * @param array $ops
 *   An array of strings: 'create', 'view', 'edit', 'delete'
 *   Use this to specify exactly what kinds of permissions should be returned
 *   for each entity type. Only include the ones you want. If none are provided,
 *   all permissions will be returned. Example:
 *     $ops = array(
 *       'create',
 *       'view',
 *       'edit',
 *       'delete',
 *     );
 *
 * @return array
 *   Returns a list of permissions for the given entity type+bundle.
 */
function farm_access_entity_perms(array $types, $ops = array()) {

  // Start with an empty array.
  $perms = array();

  // If the operations array is empty, fill it in.
  if (empty($ops)) {
    $ops = array(
      'create',
      'view',
      'edit',
      'delete',
    );
  }

  // Iterate through the types.
  foreach ($types as $type => $bundles) {

    // Iterate through the bundles.
    foreach ($bundles as $bundle) {

      // Switch through available entity types.
      switch ($type) {

        // Farm Asset.
        case 'farm_asset':

          // Create.
          if (in_array('create', $ops)) {
            $perms[] = 'create ' . $bundle . ' farm assets';
          }

          // View.
          if (in_array('view', $ops)) {
            $perms[] = 'view any ' . $bundle . ' farm assets';
            $perms[] = 'view own ' . $bundle . ' farm assets';
          }

          // Edit.
          if (in_array('edit', $ops)) {
            $perms[] = 'edit any ' . $bundle . ' farm assets';
            $perms[] = 'edit own ' . $bundle . ' farm assets';
          }

          // Delete.
          if (in_array('delete', $ops)) {
            $perms[] = 'delete any ' . $bundle . ' farm assets';
            $perms[] = 'delete own ' . $bundle . ' farm assets';
          }
          break;

        // Farm Plan.
        case 'farm_plan':

          // Create.
          if (in_array('create', $ops)) {
            $perms[] = 'create ' . $bundle . ' farm plans';
          }

          // View.
          if (in_array('view', $ops)) {
            $perms[] = 'view any ' . $bundle . ' farm plans';
            $perms[] = 'view own ' . $bundle . ' farm plans';
          }

          // Edit.
          if (in_array('edit', $ops)) {
            $perms[] = 'edit any ' . $bundle . ' farm plans';
            $perms[] = 'edit own ' . $bundle . ' farm plans';
          }

          // Delete.
          if (in_array('delete', $ops)) {
            $perms[] = 'delete any ' . $bundle . ' farm plans';
            $perms[] = 'delete own ' . $bundle . ' farm plans';
          }
          break;

        // Log.
        case 'log':

          // Create.
          if (in_array('create', $ops)) {
            $perms[] = 'create ' . $bundle . ' log entities';
          }

          // View.
          if (in_array('view', $ops)) {
            $perms[] = 'view any ' . $bundle . ' log entities';
            $perms[] = 'view own ' . $bundle . ' log entities';
          }

          // Edit.
          if (in_array('edit', $ops)) {
            $perms[] = 'edit any ' . $bundle . ' log entities';
            $perms[] = 'edit own ' . $bundle . ' log entities';
          }

          // Delete.
          if (in_array('delete', $ops)) {
            $perms[] = 'delete any ' . $bundle . ' log entities';
            $perms[] = 'delete own ' . $bundle . ' log entities';
          }
          break;

        // Taxonomy.
        case 'taxonomy':

          // Edit.
          if (in_array('edit', $ops)) {
            $perms[] = 'edit terms in ' . $bundle;
          }

          // Delete.
          if (in_array('delete', $ops)) {
            $perms[] = 'delete terms in ' . $bundle;
          }
          break;
      }
    }
  }

  // Return the permissions.
  return $perms;
}

/**
 * Implements hook_modules_enabled().
 */
function farm_access_modules_enabled($modules) {

  // Create new roles.
  farm_access_roles_create();

  // Load a list of modules that implement hook_farm_access_perms() or
  // hook_farm_access_perms_alter().
  $perms_implementations = module_implements('farm_access_perms');
  $alter_implementations = module_implements('farm_access_perms_alter');

  // If one of the modules being enabled implements hook_farm_access_perms() or
  // hook_farm_access_perms_alter(), sync permissions.
  if (array_intersect($modules, $perms_implementations) || array_intersect($modules, $alter_implementations)) {
    farm_access_sync_perms();
  }
}

/**
 * Implements hook_form_alter().
 */
function farm_access_form_alter(&$form, &$form_state, $form_id) {

  // Add our submit function to the core permissions form.
  if ($form_id == 'user_admin_permissions') {

    // Only if the role exists...
    $role = user_role_load_by_name('Farm Manager');
    if (!empty($role)) {
      $form['#submit'][] = 'farm_access_permissions_form_submit';
    }
  }
}

/**
 * Submit function for the core permissions form.
 */
function farm_access_permissions_form_submit($form, &$form_state) {

  // Create new roles.
  farm_access_roles_create();

  // Sync permissions.
  farm_access_sync_perms();

  // Tell the user that we are enforcing the permissions, so there's no
  // confusion.
  drupal_set_message(t('Farm access permissions were automatically assigned.'));
}

/**
 * Implements hook_flush_caches().
 */
function farm_access_flush_caches() {

  // Create new roles.
  farm_access_roles_create();

  // Sync permissions when the cache is cleared.
  farm_access_sync_perms();
}