在simclist库中除以零

在simclist链接列表库中，我遇到了一个问题，该函数中除以零list_findpos()。通常情况下，我会犹豫要修改广泛使用的第三方库，并且一定有充分的理由来说明它所做的事情（我并没有排除该库的使用不正确）。该函数定义为：

/* set tmp to point to element at index posstart in l */
static inline struct list_entry_s *list_findpos(const list_t *restrict l, int posstart) {
    struct list_entry_s *ptr;
    float x;
    int i;

    /* accept 1 slot overflow for fetching head and tail sentinels */
    if (posstart < -1 || posstart > (int)l->numels) return NULL;

    x = (float)(posstart+1) / l->numels;
    if (x <= 0.25) {
        /* first quarter: get to posstart from head */
        for (i = -1, ptr = l->head_sentinel; i < posstart; ptr = ptr->next, i++);
    } else if (x < 0.5) {
        /* second quarter: get to posstart from mid */
        for (i = (l->numels-1)/2, ptr = l->mid; i > posstart; ptr = ptr->prev, i--);
    } else if (x <= 0.75) {
        /* third quarter: get to posstart from mid */
        for (i = (l->numels-1)/2, ptr = l->mid; i < posstart; ptr = ptr->next, i++);
    } else {
        /* fourth quarter: get to posstart from tail */
    for (i = l->numels, ptr = l->tail_sentinel; i > posstart; ptr = ptr->prev, i--);
    }

    return ptr;
}

如果l->numels为0，则第9行上的表达式是一个问题。否则该代码可以正常运行（没有泄漏或段错误），但是intel检查员说此行上被零除。建议的更改是：

/* set tmp to point to element at index posstart in l */
static inline struct list_entry_s *list_findpos(const list_t *restrict l, int posstart) {
    struct list_entry_s *ptr;
    float x;
    int i;

    /* accept 1 slot overflow for fetching head and tail sentinels */
    if (posstart < -1 || posstart > (int)l->numels) return NULL;

    if (l->numels == 0){ //avoid division-by-zero on first element
       ptr = l->head_sentinel;
    }
    else{
       x = (float)(posstart + 1) / l->numels;
       if (x <= 0.25) {
          /* first quarter: get to posstart from head */
          for (i = -1, ptr = l->head_sentinel; i < posstart; ptr = ptr->next, i++);
       }
       else if (x < 0.5) {
          /* second quarter: get to posstart from mid */
          for (i = (l->numels - 1) / 2, ptr = l->mid; i > posstart; ptr = ptr->prev, i--);
       }
       else if (x <= 0.75) {
          /* third quarter: get to posstart from mid */
          for (i = (l->numels - 1) / 2, ptr = l->mid; i < posstart; ptr = ptr->next, i++);
       }
       else {
          /* fourth quarter: get to posstart from tail */
          for (i = l->numels, ptr = l->tail_sentinel; i > posstart; ptr = ptr->prev, i--);
       }
    }
    return ptr;
}

想知道是否有人可以对使用simclist的经验发表评论？

编辑

list_findpos不是API函数；相反，它是一个内部功能。导致问题的呼叫顺序为：

/* ... */
list_init(...) 
list_attributes_copy(...)
list_append(...) /* <---- list_findpos() is called here, divide by zero */