1#include <sys/ipc.h>
 2#include <sys/stat.h>
 3
 4key_t ftok(const char *path, int id)
 5{
 6	struct stat st;
 7	if (stat(path, &st) < 0) return -1;
 8
 9	return ((st.st_ino & 0xffff) | ((st.st_dev & 0xff) << 16) | ((id & 0xffu) << 24));
10}