1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
/************************************************************
* sched/mq_notify.c
*
* Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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 <sys/types.h> /* uint32, etc. */
#include <signal.h>
#include <mqueue.h>
#include <sched.h>
#include "os_internal.h"
#include "mq_internal.h"
/************************************************************
* Definitions
************************************************************/
/************************************************************
* Private Type Declarations
************************************************************/
/************************************************************
* Global Variables
************************************************************/
/************************************************************
* Private Variables
************************************************************/
/************************************************************
* Private Functions
************************************************************/
/************************************************************
* Public Functions
************************************************************/
/************************************************************
* Function: 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. One 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:
* None
*
* 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)
{
_TCB *rtcb;
msgq_t *msgq;
int ret = ERROR;
if (mqdes)
{
sched_lock();
/* Get a pointer to the message queue */
msgq = mqdes->msgq;
/* Get the current process ID */
rtcb = (_TCB*)g_readytorun.head;
/* Is there already a notification attached */
if (!msgq->ntmqdes)
{
/* No... Have we been asked to establish one? Make
* sure a good signal number has been provided
*/
if (notification && GOOD_SIGNO(notification->sigev_signo))
{
/* 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;
ret = OK;
}
}
/* Yes... a notification is attached. Does this task own it?
* Is it trying to remove it?
*/
else if ((msgq->ntpid == rtcb->pid) && (!notification))
{
/* Yes... Detach the notification */
msgq->ntpid = INVALID_PROCESS_ID;
msgq->ntsigno = 0;
msgq->ntvalue.sival_ptr = NULL;
msgq->ntmqdes = NULL;
ret = OK;
}
sched_unlock();
}
return ret;
}
|
