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Diffstat (limited to 'nuttx/sched/mqueue/mq_notify.c')
-rw-r--r-- | nuttx/sched/mqueue/mq_notify.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/nuttx/sched/mqueue/mq_notify.c b/nuttx/sched/mqueue/mq_notify.c new file mode 100644 index 000000000..ffb159af0 --- /dev/null +++ b/nuttx/sched/mqueue/mq_notify.c @@ -0,0 +1,211 @@ +/************************************************************************ + * sched/mqueue/mq_notify.c + * + * Copyright (C) 2007, 2009, 2011, 2013 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ************************************************************************/ + +/************************************************************************ + * Included Files + ************************************************************************/ + +#include <nuttx/config.h> + +#include <signal.h> +#include <mqueue.h> +#include <sched.h> +#include <errno.h> + +#include "os_internal.h" +#include "mqueue/mqueue.h" + +/************************************************************************ + * Definitions + ************************************************************************/ + +/************************************************************************ + * Private Type Declarations + ************************************************************************/ + +/************************************************************************ + * Global Variables + ************************************************************************/ + +/************************************************************************ + * Private Variables + ************************************************************************/ + +/************************************************************************ + * Private Functions + ************************************************************************/ + +/************************************************************************ + * Public Functions + ************************************************************************/ + +/************************************************************************ + * Name: mq_notify + * + * Description: + * If "notification" is not NULL, this function connects the task with + * the message queue such that the specified signal will be sent to the + * task whenever the message changes from empty to non-empty. Only one + * notification can be attached to a message queue. + * + * If "notification" is NULL, the attached notification is detached (if + * it was held by the calling task) and the queue is available to attach + * another notification. + * + * When the notification is sent to the registered process, its + * registration will be removed. The message queue will then be + * available for registration. + * + * Parameters: + * mqdes - Message queue descriptor + * notification - Real-time signal structure containing: + * sigev_notify - Should be SIGEV_SIGNAL (but actually ignored) + * sigev_signo - The signo to use for the notification + * sigev_value - Value associated with the signal + * + * Return Value: + * On success mq_notify() returns 0; on error, -1 is returned, with + * errno set to indicate the error. + * + * EBADF The descriptor specified in mqdes is invalid. + * EBUSY Another process has already registered to receive notification + * for this message queue. + * EINVAL sevp->sigev_notify is not one of the permitted values; or + * sevp->sigev_notify is SIGEV_SIGNAL and sevp->sigev_signo is not a + * valid signal number. + * ENOMEM + * Insufficient memory. + * + * Assumptions: + * + * POSIX Compatibility: + * int mq_notify(mqd_t mqdes, const struct sigevent *notification); + * + * The notification will be sent to the registered task even if another + * task is waiting for the message queue to become non-empty. This is + * inconsistent with the POSIX specification which says, "If a process + * has registered for notification of message a arrival at a message + * queue and some process is blocked in mq_receive() waiting to receive + * a message when a message arrives at the queue, the arriving message + * message shall satisfy mq_receive()... The resulting behavior is as if + * the message queue remains empty, and no notification shall be sent." + * + ************************************************************************/ + +int mq_notify(mqd_t mqdes, const struct sigevent *notification) +{ + struct tcb_s *rtcb; + msgq_t *msgq; + int errval; + + /* Was a valid message queue descriptor provided? */ + + if (!mqdes) + { + /* No.. return EBADF */ + + errval = EBADF; + goto errout; + } + + /* Get a pointer to the message queue */ + + sched_lock(); + msgq = mqdes->msgq; + + /* Get the current process ID */ + + rtcb = (struct tcb_s*)g_readytorun.head; + + /* Is there already a notification attached */ + + if (!msgq->ntmqdes) + { + /* No... Have we been asked to establish one? */ + + if (notification) + { + /* Yes... Was a valid signal number supplied? */ + + if (!GOOD_SIGNO(notification->sigev_signo)) + { + /* No... Return EINVAL */ + + errval = EINVAL; + goto errout; + } + + /* Yes... Assign it to the current task. */ + + msgq->ntvalue.sival_ptr = notification->sigev_value.sival_ptr; + msgq->ntsigno = notification->sigev_signo; + msgq->ntpid = rtcb->pid; + msgq->ntmqdes = mqdes; + } + } + + /* Yes... a notification is attached. Does this task own it? + * Is it trying to remove it? + */ + + else if ((msgq->ntpid != rtcb->pid) || (notification)) + { + /* This thread does not own the notification OR it is + * not trying to remove it. Return EBUSY. + */ + + errval = EBUSY; + goto errout; + } + else + { + /* Yes, the notification belongs to this thread. Allow the + * thread to detach the notification. + */ + + msgq->ntpid = INVALID_PROCESS_ID; + msgq->ntsigno = 0; + msgq->ntvalue.sival_ptr = NULL; + msgq->ntmqdes = NULL; + } + + sched_unlock(); + return OK; + +errout: + set_errno(errval); + sched_unlock(); + return ERROR; +} |