I got an assignment to create a message queue in Linux. I need to use msgnd() and msgrcv() functions. Everything works if my message structure has two fields mtype and mtext[] but I need to add one more field an int mpid. But when I read the value from mpid it is just garbage from the memory. I searched for answers or examples but I only found structures with two fields. Can I even add more?
struct myBuff{
long mtype;
char mtext[255];
int mpid;
};
code for the sender
void add_message(int id, struct myBuff buff){
int size = strlen(buff.mtext) + 1 + sizeof(int)
if (size > 255 + sizeof(int))
exit(EXIT_FAILURE);
msgsnd(id, (struct msgbuf*)&buff, size, 0 | MSG_NOERROR);
}
code for the receiver
void check_message(int id, struct myBuff* buff)
{
msgrcv(id, (struct msgbuf*)buff, 255 + sizeof(int), buff->mtype, 0 | MSG_NOERROR);
}
