NU_SUPERV_USER_VARIABLES

    /* Switch to supervisor mode */
    NU_SUPERVISOR_MODE();

#ifdef  NU_ENABLE_STACK_CHECK

    /* Call stack checking function to check for an overflow condition.  */
    TCT_Check_Stack();

#endif

    /* Initialize the number of pointers returned.  */
    pointers =  0;

    /* Protect against access to the list of created mailboxes.  */
    TCT_Protect(&MBD_List_Protect);

    /* Loop until all mailbox pointers are in the list or until the maximum
       list size is reached.  */
    node_ptr =  MBD_Created_Mailboxes_List;
    while ((node_ptr) && (pointers < maximum_pointers))
    {

        /* Place the node into the destination list.  */
        *pointer_list++ =  (NU_MAILBOX *) node_ptr;

        /* Increment the pointers variable.  */
        pointers++;

        /* Position the node pointer to the next node.  */
        node_ptr =  node_ptr -> cs_next;

        /* Determine if the pointer is at the head of the list.  */
        if (node_ptr == MBD_Created_Mailboxes_List)

            /* The list search is complete.  */
            node_ptr =  NU_NULL;
    }

    /* Release protection against access to the list of created mailboxes.  */
    TCT_Unprotect();

    /* Return to user mode */
    NU_USER_MODE();

    /* Return the number of pointers in the list.  */
    return(pointers);
}


/*************************************************************************/
/*                                                                       */
/* FUNCTION                                                              */
/*                                                                       */
/*      MBF_Mailbox_Information                                          */
/*                                                                       */
/* DESCRIPTION                                                           */
/*                                                                       */
/*      This function returns information about the specified mailbox.   */
/*      However, if the supplied mailbox pointer is invalid, the         */
/*      function simply returns an error status.                         */
/*                                                                       */
/* CALLED BY                                                             */
/*                                                                       */
/*      Application                                                      */
/*                                                                       */
/* CALLS                                                                 */
/*                                                                       */
/*      [TCT_Check_Stack]                   Stack checking function      */
/*      TCT_System_Protect                  Protect mailbox              */
/*      TCT_Unprotect                       Release protection           */
/*                                                                       */
/* INPUTS                                                                */
/*                                                                       */
/*      mailbox_ptr                         Pointer to the mailbox       */
/*      name                                Destination for the name     */
/*      suspend_type                        Destination for the type of  */
/*                                            suspension                 */
/*      message_present                     Destination for the message  */
/*                                            present flag               */
/*      tasks_waiting                       Destination for the tasks    */
/*                                            waiting count              */
/*      first_task                          Destination for the pointer  */
/*                                            to the first task waiting  */
/*                                                                       */
/* OUTPUTS                                                               */
/*                                                                       */
/*      NU_SUCCESS                          If a valid mailbox pointer   */
/*                                            is supplied                */
/*      NU_INVALID_MAILBOX                  If mailbox pointer invalid   */
/*                                                                       */
/* HISTORY                                                               */
/*                                                                       */
/*         DATE                    REMARKS                               */
/*                                                                       */
/*      03-01-1993      Created initial version 1.0                      */
/*      04-19-1993      Verified version 1.0                             */
/*      03-01-1994      Changed function interface to                    */
/*                      match the prototype,                             */
/*                      resulting in version 1.1                         */
/*                                                                       */
/*      03-18-1994      Verified version 1.1                             */
/*      11-18-1996      Corrected SPR220.                                */
/*                                                                       */
/*************************************************************************/
STATUS  MBF_Mailbox_Information(NU_MAILBOX *mailbox_ptr, CHAR *name,
                  OPTION *suspend_type, DATA_ELEMENT *message_present,
                  UNSIGNED *tasks_waiting, NU_TASK **first_task)
{

MB_MCB         *mailbox;                    /* Mailbox control block ptr */
int             i;                          /* Working integer variable  */
STATUS          completion;                 /* Completion status         */
NU_SUPERV_USER_VARIABLES

    /* Switch to supervisor mode */
    NU_SUPERVISOR_MODE();

    /* Move input mailbox pointer into internal pointer.  */
    mailbox =  (MB_MCB *) mailbox_ptr;


#ifdef  NU_ENABLE_STACK_CHECK

    /* Call stack checking function to check for an overflow condition.  */
    TCT_Check_Stack();

#endif

    /* Determine if this mailbox id is valid.  */
    if ((mailbox != NU_NULL) && (mailbox -> mb_id == MB_MAILBOX_ID))
    {

        /* Setup protection of the mailbox.  */
        TCT_System_Protect();

        /* The mailbox pointer is valid.  Reflect this in the completion
           status and fill in the actual information.  */
        completion =  NU_SUCCESS;

        /* Copy the mailbox's name.  */
        for (i = 0; i < NU_MAX_NAME; i++)
            *name++ =  mailbox -> mb_name[i];

        /* Determine the suspension type.  */
        if (mailbox -> mb_fifo_suspend)
            *suspend_type =          NU_FIFO;
        else
            *suspend_type =          NU_PRIORITY;

        /* Indicate whether or not there is a message in the mailbox.  */
        *message_present =  mailbox -> mb_message_present;

        /* Retrieve the number of tasks waiting and the pointer to the
           first task waiting.  */
        *tasks_waiting =  mailbox -> mb_tasks_waiting;
        if (mailbox -> mb_suspension_list)

            /* There is a task waiting.  */
            *first_task = (NU_TASK *)
                (mailbox -> mb_suspension_list) -> mb_suspended_task;
        else

            /* There are no tasks waiting.  */
            *first_task =  NU_NULL;

        /* Release protection.  */
        TCT_Unprotect();
    }
    else

        /* Indicate that the mailbox pointer is invalid.   */
        completion =  NU_INVALID_MAILBOX;

    /* Return to user mode */
    NU_USER_MODE();

    /* Return the appropriate completion status.  */
    return(completion);
}