#include <stdio.h>
#include <stdlib.h>
#include <sys/file.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
	int k=0;
	k=atoi(argv[1]);
	struct flock fl;
	int fd;
	char *buf=malloc(sizeof(char)*512);

	fl.l_type   = F_WRLCK;  /* F_RDLCK, F_WRLCK, F_UNLCK    */
	fl.l_whence = SEEK_SET; /* SEEK_SET, SEEK_CUR, SEEK_END */
	fl.l_start  = 0;        /* Offset from l_whence         */
	fl.l_len    = 0;        /* length, 0 = to EOF           */
	fl.l_pid    = getpid(); /* our PID                      */

	int chPid=fork();
	if(chPid)
	{


		fd = open("FILENAME.txt", O_RDWR);
		fcntl(fd, F_SETLKW, &fl);  /* F_GETLK, F_SETLK, F_SETLKW */

		int st=0;
		read(fd,buf,512);
		st=atoi(buf);
		st++;
		printf("This is child :%d\n",st);

		fl.l_type   = F_UNLCK;  /* tell it to unlock the region */
		fcntl(fd, F_SETLK, &fl); /* set the region to unlocked */
		close(fd);
	}
	int fd2=open("FILENAME.txt", O_RDWR);
	while(fcntl(fd2, F_SETLKW, &fl)<0)
	{
		//printf("ni še");
		sleep(1);
	}
	read(fd2,buf,512);
	int st2=atoi(buf);
	printf("This is parent :%d\n",st2);

	//printf("Tuki še dela\n");


	return 0;
}