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Portions of this text are reprinted and reproduced in electronic form in the Sun OS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html. 9 .\" This notice shall appear on any product containing this material. 10 .\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). 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If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner] 13 .TH MQ_SEND 3C "Oct 23, 2014" 14 .SH NAME 15 mq_send, mq_timedsend, mq_reltimedsend_np \- send a message to a message queue 16 .SH SYNOPSIS 17 .LP 18 .nf 19 #include <mqueue.h> 20 21 \fBint\fR \fBmq_send\fR(\fBmqd_t\fR \fImqdes\fR, \fBconst char *\fR\fImsg_ptr\fR, \fBsize_t\fR \fImsg_len\fR, 22 \fBunsigned\fR \fImsg_prio\fR); 23 .fi 24 25 .LP 26 .nf 27 #include <mqueue.h> 28 #include <time.h> 29 30 \fBint\fR \fBmq_timedsend\fR(\fBmqd_t\fR \fImqdes\fR, \fBconst char *\fR\fImsg_ptr\fR, 31 \fBsize_t\fR \fImsg_len\fR, \fBunsigned\fR \fImsg_prio\fR, 32 \fBconst struct timespec *restrict\fR \fIabs_timeout\fR); 33 .fi 34 35 .LP 36 .nf 37 \fBint\fR \fBmq_reltimedsend_np\fR(\fBmqd_t\fR \fImqdes\fR, \fBconst char *\fR\fImsg_ptr\fR, 38 \fBsize_t\fR \fImsg_len\fR, \fBunsigned\fR \fImsg_prio\fR, 39 \fBconst struct timespec *restrict\fR \fIrel_timeout\fR); 40 .fi 41 42 .SH DESCRIPTION 43 .sp 44 .LP 45 The \fBmq_send()\fR function adds the message pointed to by the argument 46 \fImsg_ptr\fR to the message queue specified by \fImqdes\fR. The \fImsg_len\fR 47 argument specifies the length of the message in bytes pointed to by 48 \fImsg_ptr\fR. The value of \fImsg_len\fR is less than or equal to the 49 \fImq_msgsize\fR attribute of the message queue, or \fBmq_send()\fR fails. 50 .sp 51 .LP 52 If the specified message queue is not full, \fBmq_send()\fR behaves as 53 if the message is inserted into the message queue at the position 54 indicated by the \fImsg_prio\fR argument. A message with a larger 55 numeric value of \fImsg_prio\fR is inserted before messages with lower 56 values of \fImsg_prio\fR. A message will be inserted after other 57 messages in the queue, if any, with equal \fImsg_prio\fR. The value of 58 \fImsg_prio\fR must range from zero to \fBMQ_PRIO_MAX - 1\fR. 59 .sp 60 .LP 61 If the specified message queue is full and \fBO_NONBLOCK\fR is not set in the 62 message queue description associated with \fImqdes\fR (see \fBmq_open\fR(3C) 63 and \fBmq_setattr\fR(3C)), \fBmq_send()\fR blocks until space becomes available 64 to enqueue the message, or until \fBmq_send()\fR is interrupted by a signal. If 65 more than one thread is waiting to send when space becomes available in the 66 message queue, then the thread of the highest priority which has been waiting 67 the longest is unblocked to send its message. Otherwise, it is unspecified 68 which waiting thread is unblocked. If the specified message queue is full and 69 \fBO_NONBLOCK\fR is set in the message queue description associated with 70 \fImqdes\fR, the message is not queued and \fBmq_send()\fR returns an error. 71 .sp 72 .LP 73 The \fBmq_timedsend()\fR function adds a message to the message queue specified 74 by \fImqdes\fR in the manner defined for the \fBmq_send()\fR function. However, 75 if the specified message queue is full and \fBO_NONBLOCK\fR is not set in the 76 message queue description associated with \fImqdes\fR, the wait for sufficient 77 room in the queue is terminated when the specified timeout expires. If 78 \fBO_NONBLOCK\fR is set in the message queue description, this function is 79 equivalent to \fBmq_send()\fR. 80 .sp 81 .LP 82 The \fBmq_reltimedsend_np()\fR function is identical to the 83 \fBmq_timedsend()\fR function, except that the timeout is specified as a 84 relative time interval. 85 .sp 86 .LP 87 For \fBmq_timedsend()\fR, the timeout expires when the absolute time specified 88 by \fIabs_timeout\fR passes, as measured by the \fBCLOCK_REALTIME\fR clock 89 (that is, when the value of that clock equals or exceeds \fIabs_timeout\fR), or 90 if the absolute time specified by \fIabs_timeout\fR has already been passed at 91 the time of the call. 92 .sp 93 .LP 94 For \fBmq_reltimedsend_np()\fR, the timeout expires when the time interval 95 specified by \fIrel_timeout\fR passes, as measured by the \fBCLOCK_REALTIME\fR 96 clock, or if the time interval specified by \fIrel_timeout\fR is negative at 97 the time of the call. 98 .sp 99 .LP 100 The resolution of the timeout is the resolution of the \fBCLOCK_REALTIME\fR 101 clock. The \fBtimespec\fR argument is defined in the <\fBtime.h\fR> header. 102 .sp 103 .LP 104 Under no circumstance does the operation fail with a timeout if there is 105 sufficient room in the queue to add the message immediately. The validity of 106 the timeout parameter need not be checked when there is sufficient room in the 107 queue. 108 .SH RETURN VALUES 109 .sp 110 .LP 111 Upon successful completion, \fBmq_send()\fR, \fBmq_timedsend()\fR, and 112 \fBmq_reltimedsend_np()\fR return \fB0\fR. Otherwise, no message is enqueued, 113 the functions return \fB\(mi1\fR, and \fBerrno\fR is set to indicate the error. 114 .SH ERRORS 115 .sp 116 .LP 117 The \fBmq_send()\fR, \fBmq_timedsend()\fR, and \fBmq_reltimedsend_np()\fR 118 functions will fail if: 119 .sp 120 .ne 2 121 .na 122 \fB\fBEAGAIN\fR \fR 123 .ad 124 .RS 13n 125 The \fBO_NONBLOCK\fR flag is set in the message queue description associated 126 with \fImqdes\fR, and the specified message queue is full. 127 .RE 128 129 .sp 130 .ne 2 131 .na 132 \fB\fBEBADF\fR \fR 133 .ad 134 .RS 13n 135 The \fImqdes\fR argument is not a valid message queue descriptor open for 136 writing. 137 .RE 138 139 .sp 140 .ne 2 141 .na 142 \fB\fBEINTR\fR \fR 143 .ad 144 .RS 13n 145 A signal interrupted the function call. 146 .RE 147 148 .sp 149 .ne 2 150 .na 151 \fB\fBEINVAL\fR\fR 152 .ad 153 .RS 13n 154 The value of \fImsg_prio\fR was outside the valid range. 155 .RE 156 157 .sp 158 .ne 2 159 .na 160 \fB\fBEINVAL\fR\fR 161 .ad 162 .RS 13n 163 The process or thread would have blocked, and the timeout parameter specified a 164 nanoseconds field value less than zero or greater than or equal to 1,000 165 million. 166 .RE 167 168 .sp 169 .ne 2 170 .na 171 \fB\fBEMSGSIZE\fR \fR 172 .ad 173 .RS 13n 174 The specified message length, \fImsg_len\fR, exceeds the message size attribute 175 of the message queue. 176 .RE 177 178 .sp 179 .ne 2 180 .na 181 \fB\fBETIMEDOUT\fR\fR 182 .ad 183 .RS 13n 184 The \fBO_NONBLOCK\fR flag was not set when the message queue was opened, but 185 the timeout expired before the message could be added to the queue. 186 .RE 187 188 .SH ATTRIBUTES 189 .sp 190 .LP 191 See \fBattributes\fR(5) for descriptions of the following attributes: 192 .sp 193 194 .sp 195 .TS 196 box; 197 l | l 198 l | l . 199 ATTRIBUTE TYPE ATTRIBUTE VALUE 200 _ 201 Interface Stability Committed 202 _ 203 MT-Level MT-Safe 204 _ 205 Standard See below. 206 .TE 207 208 .sp 209 .LP 210 For \fBmq_send()\fR and \fBmq_timedsend()\fR, see \fBstandards\fR(5). 211 .SH SEE ALSO 212 .sp 213 .LP 214 \fBsysconf\fR(3C), \fBmqueue.h\fR(3HEAD), \fBmq_open\fR(3C), 215 \fBmq_receive\fR(3C), \fBmq_setattr\fR(3C), \fBattributes\fR(5), 216 \fBstandards\fR(5)