Linux 中的 IS_ERR() 宏

#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
#define IS_ERR_PTR(x) ((unsigned long)(void *)(x) > (unsigned long)-MAX_ERRNO)
#define IS_ERR(x) unlikely(IS_ERR_VALUE((unsigned long)(x)) || IS_ERR_PTR(x))

c
#include 
int main() {
    int *ptr = NULL;
    ptr = (int *)-EINVAL;  // 错误指针
    if (IS_ERR(ptr)) {
        printk("ptr is an error pointer.\n");
    } else {
        printk("ptr is not an error pointer.\n");
    }
    return 0;
}