int main(int argc, char **argv)
{
int fd1, fd2, *ptr1, *ptr2;
pid_t childpid;
struct stat stat;
if (argc != 2)
err_quit("Usage: test2 <name>");
Shm_unlink(Px_ipc_name(argv[1]));
fd1 = Shm_open(Px_ipc_name(argv[1]), O_RDWR | O_CREAT | O_EXCL, FILE_MODE);
Ftruncate(fd1, sizeof(int));
fd2 = Open("./shm", O_RDONLY);
Fstat(fd2, &stat);
if ((childpid = Fork()) == 0) {
ptr2 = Mmap(NULL, stat.st_size, PROT_READ, MAP_SHARED, fd2, 0);
ptr1 = Mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE, MAP_SHARED, fd1, 0);
printf("child: shm ptr = %p, motd ptr = %p\n", ptr1, ptr2);
sleep(5);
printf("shared memory integer = %d\n", *ptr1);
exit(0);
}
//parent: map in reverse order from child
ptr1 = Mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE, MAP_SHARED, fd1, 0);
ptr2 = Mmap(NULL, stat.st_size, PROT_READ, MAP_SHARED, fd2, 0);
*ptr1 = 777;
Waitpid(childpid, NULL, 0);
exit(0);
}
int
main(int argc, char **argv)
{
if (argc != 2)
err_quit("usage: shmunlink <name>");
Shm_unlink(argv[1]);
exit(0);
}
int unlink_shmfile(const char *name){
// See notes from create_shmfile() on why we do this differently on
// FreeBSD and Linux.
#ifdef LIB_COMPAT_FREEBSD
if(Shm_unlink(name)){
return -1;
}
#else
#ifdef LIB_COMPAT_LINUX
if(Unlink(name)){
return -1;
}
#else
bitch("No support for %s on this OS\n",name);
return -1;
#endif
#endif
return 0;
}
