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80a99f39 | 1 | '\" t |
c11b1abf | 2 | .\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com> |
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80a99f39 | 25 | .\" |
4b8c67d9 | 26 | .TH MQ_SEND 3 2017-09-15 "Linux" "Linux Programmer's Manual" |
80a99f39 MK |
27 | .SH NAME |
28 | mq_send, mq_timedsend \- send a message to a message queue | |
29 | .SH SYNOPSIS | |
30 | .nf | |
31 | .B #include <mqueue.h> | |
68e4db0a | 32 | .PP |
c9e83f06 | 33 | .BI "int mq_send(mqd_t " mqdes ", const char *" msg_ptr , |
c1234a3b | 34 | .BI " size_t " msg_len ", unsigned int " msg_prio ); |
68e4db0a | 35 | .PP |
80a99f39 MK |
36 | .B #include <time.h> |
37 | .B #include <mqueue.h> | |
68e4db0a | 38 | .PP |
c9e83f06 | 39 | .BI "int mq_timedsend(mqd_t " mqdes ", const char *" msg_ptr , |
c1234a3b | 40 | .BI " size_t " msg_len ", unsigned int " msg_prio , |
b9f02710 | 41 | .BI " const struct timespec *" abs_timeout ); |
80a99f39 | 42 | .fi |
68e4db0a | 43 | .PP |
1b2d3fca | 44 | Link with \fI\-lrt\fP. |
68e4db0a | 45 | .PP |
9a30939e MK |
46 | .ad l |
47 | .in -4n | |
48 | Feature Test Macro Requirements for glibc (see | |
49 | .BR feature_test_macros (7)): | |
50 | .in | |
68e4db0a | 51 | .PP |
9a30939e MK |
52 | .BR mq_timedsend (): |
53 | .RS 4 | |
a446ac0c | 54 | _POSIX_C_SOURCE\ >=\ 200112L |
9a30939e MK |
55 | .RE |
56 | .ad | |
80a99f39 MK |
57 | .SH DESCRIPTION |
58 | .BR mq_send () | |
59 | adds the message pointed to by | |
0daa9e92 | 60 | .I msg_ptr |
d9cb0d7d | 61 | to the message queue referred to by the message queue descriptor |
80a99f39 | 62 | .IR mqdes . |
c13182ef | 63 | The |
80a99f39 MK |
64 | .I msg_len |
65 | argument specifies the length of the message pointed to by | |
66 | .IR msg_ptr ; | |
67 | this length must be less than or equal to the queue's | |
68 | .I mq_msgsize | |
69 | attribute. | |
70 | Zero-length messages are allowed. | |
847e0d88 | 71 | .PP |
c13182ef | 72 | The |
80a99f39 | 73 | .I msg_prio |
2fda57bd | 74 | argument is a nonnegative integer that specifies the priority |
80a99f39 | 75 | of this message. |
c13182ef MK |
76 | Messages are placed on the queue in decreasing order of priority, |
77 | with newer messages of the same priority being placed after | |
80a99f39 | 78 | older messages with the same priority. |
c1b9bce2 MK |
79 | See |
80 | .BR mq_overview (7) | |
81 | for details on the range for the message priority. | |
847e0d88 | 82 | .PP |
c13182ef | 83 | If the message queue is already full |
80a99f39 MK |
84 | (i.e., the number of messages on the queue equals the queue's |
85 | .I mq_maxmsg | |
86 | attribute), then, by default, | |
87 | .BR mq_send () | |
c13182ef | 88 | blocks until sufficient space becomes available to allow the message |
80a99f39 | 89 | to be queued, or until the call is interrupted by a signal handler. |
c13182ef | 90 | If the |
80a99f39 MK |
91 | .B O_NONBLOCK |
92 | flag is enabled for the message queue description, | |
93 | then the call instead fails immediately with the error | |
94 | .BR EAGAIN . | |
847e0d88 | 95 | .PP |
80a99f39 MK |
96 | .BR mq_timedsend () |
97 | behaves just like | |
98 | .BR mq_send (), | |
99 | except that if the queue is full and the | |
100 | .B O_NONBLOCK | |
101 | flag is not enabled for the message queue description, then | |
102 | .I abs_timeout | |
3824cf5b MK |
103 | points to a structure which specifies how long the call will block. |
104 | This value is an absolute timeout in seconds and nanoseconds | |
105 | since the Epoch, 1970-01-01 00:00:00 +0000 (UTC), | |
80a99f39 | 106 | specified in the following structure: |
bdd915e2 | 107 | .PP |
bd191423 | 108 | .in +4n |
b8302363 | 109 | .EX |
80a99f39 MK |
110 | struct timespec { |
111 | time_t tv_sec; /* seconds */ | |
112 | long tv_nsec; /* nanoseconds */ | |
113 | }; | |
b8302363 | 114 | .EE |
bd191423 | 115 | .in |
bdd915e2 | 116 | .PP |
80a99f39 MK |
117 | If the message queue is full, |
118 | and the timeout has already expired by the time of the call, | |
119 | .BR mq_timedsend () | |
120 | returns immediately. | |
121 | .SH RETURN VALUE | |
122 | On success, | |
123 | .BR mq_send () | |
124 | and | |
125 | .BR mq_timedsend () | |
126 | return zero; on error, \-1 is returned, with | |
c13182ef | 127 | .I errno |
80a99f39 MK |
128 | set to indicate the error. |
129 | .SH ERRORS | |
130 | .TP | |
131 | .B EAGAIN | |
78ca89ac | 132 | The queue was full, and the |
80a99f39 MK |
133 | .B O_NONBLOCK |
134 | flag was set for the message queue description referred to by | |
135 | .IR mqdes . | |
136 | .TP | |
137 | .B EBADF | |
e186d0ca | 138 | The descriptor specified in |
80a99f39 | 139 | .I mqdes |
e1ca8255 | 140 | was invalid or not opened for writing. |
80a99f39 | 141 | .TP |
80a99f39 | 142 | .B EINTR |
01538d0d MK |
143 | The call was interrupted by a signal handler; see |
144 | .BR signal (7). | |
80a99f39 MK |
145 | .TP |
146 | .B EINVAL | |
c13182ef | 147 | The call would have blocked, and |
80a99f39 MK |
148 | .I abs_timeout |
149 | was invalid, either because | |
150 | .I tv_sec | |
151 | was less than zero, or because | |
c13182ef | 152 | .I tv_nsec |
80a99f39 MK |
153 | was less than zero or greater than 1000 million. |
154 | .TP | |
eab64696 | 155 | .B EMSGSIZE |
0daa9e92 | 156 | .I msg_len |
eab64696 MK |
157 | was greater than the |
158 | .I mq_msgsize | |
159 | attribute of the message queue. | |
160 | .TP | |
80a99f39 MK |
161 | .B ETIMEDOUT |
162 | The call timed out before a message could be transferred. | |
dfc41d9c | 163 | .SH ATTRIBUTES |
7ec57137 PH |
164 | For an explanation of the terms used in this section, see |
165 | .BR attributes (7). | |
166 | .TS | |
167 | allbox; | |
168 | lbw25 lb lb | |
169 | l l l. | |
170 | Interface Attribute Value | |
171 | T{ | |
172 | .BR mq_send (), | |
dfc41d9c | 173 | .BR mq_timedsend () |
7ec57137 PH |
174 | T} Thread safety MT-Safe |
175 | .TE | |
80a99f39 | 176 | .SH CONFORMING TO |
fcabb4b1 | 177 | POSIX.1-2001, POSIX.1-2008. |
5496c8c1 MK |
178 | .SH NOTES |
179 | On Linux, | |
180 | .BR mq_timedsend () | |
181 | is a system call, and | |
182 | .BR mq_send () | |
183 | is a library function layered on top of that system call. | |
47297adb | 184 | .SH SEE ALSO |
80a99f39 MK |
185 | .BR mq_close (3), |
186 | .BR mq_getattr (3), | |
187 | .BR mq_notify (3), | |
188 | .BR mq_open (3), | |
189 | .BR mq_receive (3), | |
190 | .BR mq_unlink (3), | |
1d7c4d16 MK |
191 | .BR mq_overview (7), |
192 | .BR time (7) |