Function traverse_role_graph_impl

sql/sql_acl.cc:6568–6698

Traverse the role grant graph and invoke callbacks at the specified points. @param user user or role to start traversal from @param context opaque parameter to pass to callbacks @param offset offset to ACL_ROLE::parent_grantee or to ACL_USER_BASE::role_grants. Depending on this value, traversal will go from roles to

                            this error code
*/
static int traverse_role_graph_impl(ACL_USER_BASE *user, void *context,
       off_t offset,
       int (*on_node) (ACL_USER_BASE *role, void *context),
       int (*on_edge) (ACL_USER_BASE *current, ACL_ROLE *neighbour, void *context))
{
  DBUG_ENTER("traverse_role_graph_impl");
  DBUG_ASSERT(user);
  DBUG_PRINT("enter",("role: '%s'", user->user.str));
  /*
     The search operation should always leave the ROLE_ON_STACK and
     ROLE_EXPLORED flags clean for all nodes involved in the search
  */
  DBUG_ASSERT(!(user->flags & ROLE_ON_STACK));
  DBUG_ASSERT(!(user->flags & ROLE_EXPLORED));
  mysql_mutex_assert_owner(&acl_cache->lock);

  /*
     Stack used to simulate the recursive calls of DFS.
     It uses a Dynamic_array to reduce the number of
     malloc calls to a minimum
  */
  Dynamic_array<NODE_STATE> stack(PSI_INSTRUMENT_MEM, 20,50);
  Dynamic_array<ACL_USER_BASE *> to_clear(PSI_INSTRUMENT_MEM, 20, 50);
  NODE_STATE state;     /* variable used to insert elements in the stack */
  int result= 0;

  state.neigh_idx= 0;
  state.node_data= user;
  user->flags|= ROLE_ON_STACK;

  stack.push(state);
  to_clear.push(user);

  user->flags|= ROLE_OPENED;
  if (on_node && ((result= on_node(user, context)) < 0))
    goto end;

  while (stack.elements())
  {
    NODE_STATE *curr_state= stack.back();

    DBUG_ASSERT(curr_state->node_data->flags & ROLE_ON_STACK);

    ACL_USER_BASE *current= curr_state->node_data;
    ACL_USER_BASE *neighbour= NULL;
    DBUG_PRINT("info", ("Examining role %s", current->user.str));
    /*
      Iterate through the neighbours until a first valid jump-to
      neighbour is found
    */
    bool found= FALSE;
    uint i;
    DYNAMIC_ARRAY *array= (DYNAMIC_ARRAY *)(((char*)current) + offset);

    DBUG_ASSERT(array == &current->role_grants || current->flags & IS_ROLE);
    for (i= curr_state->neigh_idx; i < array->elements; i++)
    {
      neighbour= *(dynamic_element(array, i, ACL_ROLE**));