我使用shm_open（）在c语言中申请了一块共享内存，然后使用mmap（）将其转换为Struct MinHeap* 类型。由于MinHeap结构体内部有struct Element elementd[16]，我如何修改元素的值？我按照下面的方法做了，但当程序运行到init_elm（）并试图分配标志时失败。

struct Element{
    int flag;
    int id;
    char name[32];
};

struct MinHeap{
    struct Element elements[16];
    int size;
    int capacity;
};

void init_elm(struct Element* elm){
    elm->flag=FREE;//---------------------------------WRONG HERE
    elm->id=-1;
    strcpy(elm->name,"Unamed");
}

void init_heap(struct MinHeap* heap){
    for(int i=0;i<CAPACITY;i++){
        init_elm(&(heap->elements[i]));
    }
    heap->elements[0].id=INT_MIN;
    heap->capacity=CAPACITY;
    heap->size=0;
}

char* shm_file = SHM_FILE_NAME;
size_t  shm_size = 32*sizeof(struct MinHeap);
key_t shm_fd = shm_open(SHM_FILE_NAME,O_CREAT|O_RDWR, 0666);
ftruncate(shm_fd,shm_size);
struct MinHeap* mhp_p = (struct MinHeap*)mmap(0,shm_size,PROT_READ,MAP_SHARED,shm_fd,0);/*MinHeap pointer to shared memory*/
init_heap(mhp_p);