地址边界错误 - 为什么链表中的节点没有正确添加？

问：

我正在尝试用 C 语言实现链表，但是我似乎无法弄清楚如何将元素附加到列表中。

#include <malloc.h>
#include <stdio.h>
#include <stdlib.h>

typedef struct element {
    int value;
    struct element* next;
} element;

typedef struct list {
    element* head;
} list;

list* createList(int headValue) {
    list* L = malloc(sizeof(list));
    L->head = malloc(sizeof(element));
    L->head->value = headValue;
    L->head->next = NULL;
    return L;
}

// Returns the new length of the list
int appendToList(list* L, int value) {
    element* first = L->head;
    element* current = first;
    int length = 1;
    
    if (first == NULL) {
        printf("first is NULL\n");
        exit(2);
    }
    while (current != NULL) {
        current = current->next;
        length++;
    }
 
    current = malloc(sizeof(element));
    current->next = NULL;
    current->value = value;
    length++;

    return length;
}

// returns the value at index N (zero based)
//
// If the list has < N elements, returns -1 
int getAtIndexN(list* L, int N) {
    element* current = L->head;
    for (int i=0; i<N; i++) {
        if (current->next == NULL) {
            printf("unable to get to index %d\n", i+1);
            exit(1);
        }
        current = current->next;
    }
    return current->value;
}

int main(int args, char** argv) {
    int initvalues[] = {1,3,4,4};
    list* L = createList(5);
    for (int i=0; i<4; i++) {
        appendToList(L, initvalues[i]);
    }
    
    printf("element at index 1 has value %d\n", L->head->next->value);
    return 0;
}

我调用了 4 次，以便将值附加到列表中，但似乎只有列表的头部被正确添加到列表中。in 的结果为 。我不确定问题出在其他地方还是其他地方。appendToListinitvaluesprintfmain'./a.out' terminated by signal SIGSEGV (Address boundary error)appendToList