text: /****************************************************************************
   * sched/mqueue/mq_sndinternal.c
   *
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.  The
   * ASF licenses this file to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance with the
   * License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations
   * under the License.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <sys/types.h>
  #include <stdint.h>
  #include <fcntl.h>
  #include <mqueue.h>
  #include <string.h>
  #include <errno.h>
  #include <sched.h>
  #include <debug.h>
  
  #include <nuttx/irq.h>
  #include <nuttx/kmalloc.h>
  #include <nuttx/arch.h>
  #include <nuttx/sched.h>
  #include <nuttx/cancelpt.h>
  
  #include "sched/sched.h"
  #include "mqueue/mqueue.h"
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: nxmq_verify_send
   *
   * Description:
   *   This is internal, common logic shared by both [nx]mq_send and
   *   [nx]mq_timesend.  This function verifies the input parameters that are
   *   common to both functions.
   *
   * Input Parameters:
   *   msgq   - Message queue descriptor
   *   oflags - flags from user set
   *   msg    - Message to send
   *   msglen - The length of the message in bytes
   *   prio   - The priority of the message
   *
   * Returned Value:
   *   One success, 0 (OK) is returned. On failure, a negated errno value is
   *   returned.
   *
   *     EINVAL   Either msg or msgq is NULL or the value of prio is invalid.
   *     EPERM    Message queue opened not opened for writing.
   *     EMSGSIZE 'msglen' was greater than the maxmsgsize attribute of the
   *               message queue.
   *
   ****************************************************************************/
  
  int nxmq_verify_send(FAR struct mqueue_inode_s *msgq, int oflags,
                       FAR const char *msg, size_t msglen, unsigned int prio)
  {
    /* Verify the input parameters */
  
    if (msg == NULL || msgq == NULL || prio > MQ_PRIO_MAX)
      {
        return -EINVAL;
      }
  
    if ((oflags & O_WROK) == 0)
      {
        return -EPERM;
      }
  
    if (msglen > (size_t)msgq->maxmsgsize)
      {
        return -EMSGSIZE;
      }
  
    return OK;
  }
  
  /****************************************************************************
   * Name: nxmq_alloc_msg
   *
   * Description:
   *   The nxmq_alloc_msg function will get a free message for use by the
   *   operating system.  The message will be allocated from the g_msgfree
   *   list.
   *
   *   If the list is empty AND the message is NOT being allocated from the
   *   interrupt level, then the message will be allocated.  If a message
   *   cannot be obtained, the operating system is dead and therefore cannot
   *   continue.
   *
   *   If the list is empty AND the message IS being allocated from the
   *   interrupt level.  This function will attempt to get a message from
   *   the g_msgfreeirq list.  If this is unsuccessful, the calling interrupt
   *   handler will be notified.
   *
   * Input Parameters:
   *   None
   *
   * Returned Value:
   *   A reference to the allocated msg structure.  On a failure to allocate,
   *   this function PANICs.
   *
   ****************************************************************************/
  
  FAR struct mqueue_msg_s *nxmq_alloc_msg(void)
  {
    FAR struct mqueue_msg_s *mqmsg;
    irqstate_t flags;
  
    /* If we were called from an interrupt handler, then try to get the message
     * from generally available list of messages. If this fails, then try the
     * list of messages reserved for interrupt handlers
     */
  
    if (up_interrupt_context())
      {
        /* Try the general free list */
  
        mqmsg = (FAR struct mqueue_msg_s *)sq_remfirst(&g_msgfree);
        if (mqmsg == NULL)
          {
            /* Try the free list reserved for interrupt handlers */
  
            mqmsg = (FAR struct mqueue_msg_s *)sq_remfirst(&g_msgfreeirq);
          }
      }
  
    /* We were not called from an interrupt handler. */
  
    else
      {
        /* Try to get the message from the generally available free list.
         * Disable interrupts -- we might be called from an interrupt handler.
         */
  
        flags = enter_critical_section();
        mqmsg = (FAR struct mqueue_msg_s *)sq_remfirst(&g_msgfree);
        leave_critical_section(flags);
  
        /* If we cannot a message from the free list, then we will have to
         * allocate one.
         */
  
        if (mqmsg == NULL)
          {
            mqmsg = (FAR struct mqueue_msg_s *)
              kmm_malloc((sizeof (struct mqueue_msg_s)));
  
            /* Check if we allocated the message */
  
            if (mqmsg != NULL)
              {
                /* Yes... remember that this message was dynamically
                 * allocated.
                 */
  
                mqmsg->type = MQ_ALLOC_DYN;
              }
          }
      }
  
    return mqmsg;
  }
  
  /****************************************************************************
   * Name: nxmq_wait_send
   *
   * Description:
   *   This is internal, common logic shared by both [nx]mq_send and
   *   [nx]mq_timesend.  This function waits until the message queue is not
   *   full.
   *
   * Input Parameters:
   *   msgq   - Message queue descriptor
   *   oflags - flags from user set
   *
   * Returned Value:
   *   On success, nxmq_wait_send() returns 0 (OK); a negated errno value is
   *   returned on any failure:
   *
   *   EAGAIN   The queue was full and the O_NONBLOCK flag was set for the
   *            message queue description referred to by msgq.
   *   EINTR    The call was interrupted by a signal handler.
   *   ETIMEOUT A timeout expired before the message queue became non-full
   *            (mq_timedsend only).
   *
   * Assumptions/restrictions:
   * - The caller has verified the input parameters using nxmq_verify_send().
   * - Executes within a critical section established by the caller.
   *
   ****************************************************************************/
  
  int nxmq_wait_send(FAR struct mqueue_inode_s *msgq, int oflags)
  {
    FAR struct tcb_s *rtcb;
    int ret;
  
  #ifdef CONFIG_CANCELLATION_POINTS
    /* nxmq_wait_send() is not a cancellation point, but may be called via
     * mq_send() or mq_timedsend() which are cancellation points.
     */
  
    if (check_cancellation_point())
      {
        /* If there is a pending cancellation, then do not perform
         * the wait.  Exit now with ECANCELED.
         */
  
        return -ECANCELED;
      }
  #endif
  
    /* Verify that the queue is indeed full as the caller thinks */
  
    if (msgq->nmsgs >= msgq->maxmsgs)
      {
        /* Should we block until there is sufficient space in the
         * message queue?
         */
  
        if ((oflags & O_NONBLOCK) != 0)
          {
            /* No... We will return an error to the caller. */
  
            return -EAGAIN;
          }
  
        /* Yes... We will not return control until the message queue is
         * available or we receive a signal or at timeout occurs.
         */
  
        else
          {
            /* Loop until there are fewer than max allowable messages in the
             * receiving message queue
             */
  
            while (msgq->nmsgs >= msgq->maxmsgs)
              {
                /* Block until the message queue is no longer full.
                 * When we are unblocked, we will try again
                 */
  
                rtcb           = this_task();
                rtcb->msgwaitq = msgq;
                msgq->nwaitnotfull++;
  
                /* Initialize the errcode used to communication wake-up error
                 * conditions.
                 */
  
                rtcb->errcode = OK;
  
                /* Make sure this is not the idle task, descheduling that
                 * isn't going to end well.
                 */
  
                DEBUGASSERT(NULL != rtcb->flink);
                up_block_task(rtcb, TSTATE_WAIT_MQNOTFULL);
  
                /* When we resume at this point, either (1) the message queue
                 * is no longer empty, or (2) the wait has been interrupted by
                 * a signal.  We can detect the latter case be examining the
                 * per-task errno value (should be EINTR or ETIMEOUT).
                 */
  
                ret = rtcb->errcode;
                if (ret != OK)
                  {
                    return -ret;
                  }
              }
          }
      }
  
    return OK;
  }
  
  /****************************************************************************
   * Name: nxmq_do_send
   *
   * Description:
   *   This is internal, common logic shared by both [nx]mq_send and
   *   [nx]mq_timesend.  This function adds the specified message (msg) to the
   *   message queue (msgq).  Then it notifies any tasks that were waiting
   *   for message queue notifications setup by mq_notify.  And, finally, it
   *   awakens any tasks that were waiting for the message not empty event.
   *
   * Input Parameters:
   *   msgq   - Message queue descriptor
   *   msg    - Message to send
   *   msglen - The length of the message in bytes
   *   prio   - The priority of the message
   *
   * Returned Value:
   *   This function always returns OK.
   *
   ****************************************************************************/
  
  int nxmq_do_send(FAR struct mqueue_inode_s *msgq,
                   FAR struct mqueue_msg_s *mqmsg,
                   FAR const char *msg, size_t msglen, unsigned int prio)
  {
    FAR struct tcb_s *btcb;
    FAR struct mqueue_msg_s *next;
    FAR struct mqueue_msg_s *prev;
    irqstate_t flags;
  
    /* Get a pointer to the message queue */
  
    sched_lock();
  
    /* Construct the message header info */
  
    mqmsg->priority = prio;
    mqmsg->msglen   = msglen;
  
    /* Copy the message data into the message */
  
    memcpy((FAR void *)mqmsg->mail, (FAR const void *)msg, msglen);
  
    /* Insert the new message in the message queue */
  
    flags = enter_critical_section();
  
    /* Search the message list to find the location to insert the new
     * message. Each is list is maintained in ascending priority order.
     */
  
    for (prev = NULL, next = (FAR struct mqueue_msg_s *)msgq->msglist.head;
         next && prio <= next->priority;
         prev = next, next = next->next);
  
    /* Add the message at the right place */
  
    if (prev)
      {
        sq_addafter((FAR sq_entry_t *)prev, (FAR sq_entry_t *)mqmsg,
                    &msgq->msglist);
      }
    else
      {
        sq_addfirst((FAR sq_entry_t *)mqmsg, &msgq->msglist);
      }
  
    /* Increment the count of messages in the queue */
  
    if (msgq->nmsgs++ == 0)
      {
        nxmq_pollnotify(msgq, POLLIN);
      }
  
    leave_critical_section(flags);
  
    /* Check if we need to notify any tasks that are attached to the
     * message queue
     */
  
    if (msgq->ntpid != INVALID_PROCESS_ID)
      {
        struct sigevent event;
        pid_t pid;
  
        /* Remove the message notification data from the message queue. */
  
        memcpy(&event, &msgq->ntevent, sizeof(struct sigevent));
        pid = msgq->ntpid;
  
        /* Detach the notification */
  
        memset(&msgq->ntevent, 0, sizeof(struct sigevent));
        msgq->ntpid = INVALID_PROCESS_ID;
  
        /* Notification the client */
  
        DEBUGVERIFY(nxsig_notification(pid, &event,
                                       SI_MESGQ, &msgq->ntwork));
      }
  
    /* Check if any tasks are waiting for the MQ not empty event. */
  
    flags = enter_critical_section();
    if (msgq->nwaitnotempty > 0)
      {
        /* Find the highest priority task that is waiting for
         * this queue to be non-empty in g_waitingformqnotempty
         * list. sched_lock() should give us sufficient protection since
         * interrupts should never cause a change in this list
         */
  
        for (btcb = (FAR struct tcb_s *)g_waitingformqnotempty.head;
             btcb && btcb->msgwaitq != msgq;
             btcb = btcb->flink)
          {
          }
  
        /* If one was found, unblock it */
  
        DEBUGASSERT(btcb);
  
        btcb->msgwaitq = NULL;
        msgq->nwaitnotempty--;
        up_unblock_task(btcb);
      }
  
    leave_critical_section(flags);
    sched_unlock();
    return OK;
  }
  