Two Ways To Share

void *bump(void *arg) { *(int *)arg = 2; return NULL; }

int main(void) {
    int *buf = malloc(sizeof(int));
    *buf = 0;

    if (fork() == 0) { *buf = 1; _exit(0); }
    wait(NULL);
    printf("after fork:   %d\n", *buf);

    pthread_t t;
    pthread_create(&t, NULL, bump, buf);
    pthread_join(t, NULL);
    printf("after thread: %d\n", *buf);
}

What does this print?