c - struct 中 char* 上的 malloc 的段错误

Question

我正在自学 C，为了好玩，我认为编写一个小型 Web 框架会很酷。我目前正在处理的代码用于注册路由/处理程序。

我遇到了 malloc 的段错误，但奇怪的是它只在第四次被调用时出现。我已经在代码中标记了发生段错误的位置。除了用 printf 和 puts 包装代码区域外，我不确定如何调试它。我试过使用 valgrind 来调试它，但是当我运行 valgrind 时段错误实际上并没有发生。不过，Valgrind 确实告诉我，同一 malloc 存在内存泄漏。所以很明显我在那里做错了什么，但我不知道是什么。

仅供引用，destroy_routes 在子进程终止之前被调用。

struct route {
    char *path;
    enum method method;
    int(*handler)(struct request *, int sock);
    struct route *next;
};


static struct route *routes;

void
register_route(char *path, enum method method,
               int(*handler)(struct request *, int))
{
    struct route *route;

    if (routes == NULL)
        routes = route = malloc(sizeof(struct route));
    else {
        route = routes;
        while (route->next)
            route = route->next;

        route->next = malloc(sizeof(struct route));
        route = route->next;
    }

    route->path = malloc((strlen(path) + 1) * sizeof(char)); /* <== HERE is where the segmentation fault occurs only on the fourth time */
    strcpy(route->path, path);

    route->method = method;
    route->handler = handler;

    printf("route created: %s, %i, %p\n", route->path, route->method, (void *)route->handler);
}

void
destroy_routes()
{
    struct route *prev;
    int i = 0;
    while (routes) {
        free(routes->path);
        prev = routes;
        routes = routes->next;
        free(prev);
        i++;
    }
    printf("destroyed %i routes\n", i);
}

void
register_routes()
{
    register_route("/post", GET, &do_something);
    register_route("/post", POST, &do_something_else);
    register_route("/post/:id", GET, &do_something);
    register_route("/post/:id/children", POST, &do_something_else);
}

Answer 1

您没有将 next 指针设置为 NULL。这可能是问题所在。

route->method = method;
route->handler = handler;
route->next = NULL;