c - 每次调用 strtok_r() 时都会出现段错误，即使在简单的情况下也是如此

Question

我已阅读manual对于 strtok_r，我相对确定我使用正确，但每次都会出现段错误。

所以我决定编写一个快速测试程序，发现这也存在段错误:

//This define probably not necessary
//POSIX_C_SOURCE is defined as 200809L on my system
//It still doesn't work even with this define though..
#define _POSIX_SOURCE 

#include <stdio.h>
#include <string.h>

int main(void)
{
    char input[255];
    char* token;
    char** saveptr;

    memset(input, 0, sizeof(char) * 255);
    fgets(input, sizeof(input), stdin);
    token = strtok_r(input, ":", saveptr);
}

来自 valgrind 的回溯:

==15796== Command: ./a.out
==15796== 
==15796== Use of uninitialised value of size 8
==15796==    at 0x4EDABA4: strtok_r (strtok_r.c:73)
==15796==    by 0x10878B: main (in /home/pluh/a.out)
==15796== 
==15796== Invalid write of size 8
==15796==    at 0x4EDABA4: strtok_r (strtok_r.c:73)
==15796==    by 0x10878B: main (in /home/pluh/a.out)
==15796==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
==15796== 
==15796== 
==15796== Process terminating with default action of signal 11 (SIGSEGV)

我只在标准输入中放入“test”，所以我知道它没有溢出。我在这里做错了什么吗？这是我能想到的最简单的使用场景，但仍然失败。

Answer 1

试试这个方法:

int main(void)
{
    char input[255];
    char* token;
    char* saveptr;

    fgets(input, sizeof(input), stdin);
    token = strtok_r(input, ":", &saveptr);

    printf("%s, %s\n",token,saveptr);
}