如题，编译可以通过，运行不对，，代码如下：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

#define TM_L 14

typedef struct _calllist calllist;

struct _calllist
{
    long id;
    int type;
    long telnum;
    char btime[TM_L];
    long tcount;
    float charge_rate;
    float charge_sum;
};

typedef struct _calllist calllist;
int selectdb(calllist **cl,int f)
{
    printf ("hehihei");
    int i = sizeof(calllist);
    long length = lseek(f,0,SEEK_END);
    if (length < i)
    {
        puts("empty");
        return -1;
    }
    if (*cl != NULL)
    {
        free(*cl);
    }
    *cl = malloc(length);
    lseek(f,0,SEEK_SET);
    if (read(f, *cl, length) != length)
    {
        perror("error");
        return -2;
    }
    printf ("haha");
    return 0;
}
int insertdb(calllist * cr,int f,calllist *cl)
{
    printf ("dfjdk");
    int i;
    i = sizeof(calllist);
    int length = lseek(f,0,SEEK_END);
    cr -> id = (cl + length/i - 1) -> id + 1;
    
    printf ("1");
    lseek(f,0,SEEK_END);
    if (write(f,cr,i) != i)
    {
        perror("error");
        return -1;
    }
    printf ("4");
    return 0;
}


void printdb(calllist * cl,int f)
{
    int i = sizeof(calllist);
    long length = lseek(f,0,SEEK_END);
    int j;
    char btime[TM_L + 1] = {0};
    
    for (j = 0; j<length/i; j++)
    {
        memcpy(btime, (cl+j) -> btime,TM_L);
        printf ("ahha");
        printf ("%ld,%d,%ld,%14s,%ld,%1.2f,%1.2f\n",
            (cl+j) -> id,
            (cl+j) -> type,
            (cl+j) -> telnum,
            btime,
            (cl+j) -> tcount,
            (cl+j) -> charge_rate,
            (cl+j) -> charge_sum);

    }
}


int main()
{
    int f;
    int res;
    calllist cr = {1,0,12354,"34343434343444",30,3.55,3.44};
    
    calllist *cl;
    cl = NULL;
    
    f = open("listdb",O_RDWR | O_CREAT,0664);
    if (f == -1)
    {
        perror("error");
        return 1;
    }
    puts("the original file:");
    res = selectdb(&cl,f);
    if (res == -2)
    {
        return 1;
    }
    else if(res == 0)
    {
        printdb(cl,f);
    }
    puts("insert hou file:");
    insertdb(&cr,f,cl);
    printf ("djfkd");
    res = selectdb(&cl,f);
    if (res == -2)
    {
        return 1;
    }
    else if(res == 0)
    {
        printdb(cl,f);
    }
    close(f);    
    return 0;
}

运行显示：Segmentation fault（core dumped），应该是insert函数不对，这是为什么啊，，希望大家帮忙看看

恩恩，，应该就是这的问题，，那这样的话应该咋改比较好呢