//-lrt kapcsoló
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <unistd.h>
#include <mqueue.h>
#include <stdlib.h>
#include <ctype.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <sched.h>
#include <signal.h>
#include <bits/siginfo.h>

#define MSGSIZE 40
#define MAXMSGS 5
#define VALUE 1234

// Posix message queue demo program

int val, code;
//
void handler(int signo, siginfo_t *info, void *ignored)
{
psignal(signo, "Signal handler:\t\t"); // writes text, and : signo name
val = info->si_value.sival_int; // info comes from notify sigev_value 
code = info->si_code; // This is SI_MESGQ
return;
}

int main(int argc, char **argv)
{
struct sigaction act;
struct sigevent notify;
struct mq_attr attr;
sigset_t set;
char *mqname = "/almafa"; // mqname must start with / !!!!!
char rcv_buf[MSGSIZE];
mqd_t mqdes1, mqdes2;
pid_t pid, cpid;
int status;
//memset(&attr, 0, sizeof( attr));
attr.mq_maxmsg = MAXMSGS; // < /proc/sys/fs/mqueue/msg_max
attr.mq_msgsize = MSGSIZE;// < /proc/sys/fs/mqueue/msgsize_max
mq_unlink(mqname);  // remove if exists
mqdes1 = mq_open(mqname, O_CREAT|O_RDWR, 0600, &attr);
sigemptyset(&set);
act.sa_flags = SA_SIGINFO; // signal info will be transferred via sigev_value
act.sa_mask = set;	// every signal is accepted
act.sa_sigaction = handler;
sigaction(SIGUSR1, &act, 0); // SIGUSR1 could be SIGRTMAX
notify.sigev_notify = SIGEV_SIGNAL; // normal signal, SIGEV_NONE,SIGEV_THREAD
notify.sigev_signo = SIGUSR1; // SIGRTMAX
notify.sigev_value.sival_int = VALUE; // this data is also sent by notification
				// SIGEV_NONE is set, no data send
// This sigev_value.sival_int will be sent to handler siginfo_t si_value field
// The siginfo_t si_code will be SI_MESQ, and si_signo is set to signal number
// si_pid is the pid of sending message, si_uid the user id
mq_notify(mqdes1, &notify); // mq notification is set, so 
printf("\nMain program:\tTesting mq notification!\n\n");
printf("Main program:\tsigev_value=%d\n",notify.sigev_value.sival_int);
if( (pid = fork()) < 0) 
	{
	printf("fork: Error\n");
	printf("Test FAILED\n");
	exit(-1) ;
	}
if(pid == 0) // child
	{
	cpid = getpid() ;
	mqdes2 = mq_open(mqname, O_CREAT|O_RDWR, 0600, &attr);
	// no necessary to use other mq id!
	printf("Child:\t\t\tSending message to empty queue\n");
	printf("Child:\t\t\tAt the same time, sending a notification to the parent!\n");
	mq_send(mqdes2, "Hajra Vasas!", MSGSIZE, 30);
	mq_close(mqdes2);
	printf("Child:\t\t\tFinished!\n");
	exit(0); // child exit
	}
else 
	{ /* parent */
	waitpid( cpid, &status, 0); /* keep child status from init */
	printf("Parent:\t\t\tChild process exited, so message is sent!\n");
	printf("Parent:\t\t\tWaiting for notification\n");
	while(code != SI_MESGQ) // waiting for the handler, code is set
		sleep(1);	// in the handler
	printf("Parent:\t\t\tHandler is OK!\n");
	mq_receive(mqdes1, rcv_buf, MSGSIZE, 0);
	printf("Parent:\t\t\tQueue transition occured - received: %s\n",rcv_buf);
	}
printf("Parent:\t\tsi_code=%d\n",code);
printf("Parent:\t\tsi_value=%d\n",val);
if(code != -3 || val != VALUE) // the value of SI_MESGQ is -3
 {
	printf("\nTest FAILED\n\n");
	return(-1);
 }
mq_close(mqdes1);
mq_unlink(mqname);
printf("\nThe mq sample is finished!\n");
return(0);
}