msgrcv

message queue. msgsend msgrcv. System V IPC system calls in C (Linux)

Hi I'm working with some shared memory where different processes read and write data. I'm using a message queue to store messages of when data has changed between read and write operations. /* struct that defines a message */ struct msgbuf{ long mtype; /* must be positive */ int childId; //ID of child sending message ...

IPC message queue. msgrcv system call. System V. how to get out of loop.

Hi, I have a message queue from which I am getting messages in a loop. The problem is that I don't know how to exit the loop. msgrcv returns type size_t so it keeps going. What value should I compare the return value so I can exit the loop? while(msgrcv(msqid, &msgreceived, sizeof(msgreceived), BUFFER_CHANGED, 0) != -1){ printf("%d %d ...