MSGSND(2) | NetBSD System Calls Manual | MSGSND(2) |
struct mymsg { long mtype; /* message type */ char mtext[1]; /* body of message */ };
The mtype field is an integer greater than 0 that can be used for selecting messages (see msgrcv(2)). The mtext field is an array of bytes, with size up to the system limit MSGMAX.
If the number of bytes already on the message queue plus msgsz is greater than the maximum number of bytes in the message queue (msg_qbytes, see msgctl(2)), or if the number of messages on all queues system-wide is already equal to the system limit, msgflg determines the action of msgsnd(). If msgflg has IPC_NOWAIT mask set in it, the call will return immediately. If msgflg does not have IPC_NOWAIT set in it, the call will block until:
After a successful call, the data structure associated with the message queue is updated in the following way:
The message queue was removed while msgsnd() was waiting for a resource to become available in order to deliver the message.
The msgsz argument is greater than msg_qbytes or SSIZE_MAX.
April 30, 2010 | NetBSD 5.99 |