取消引用 pcap_t 结构的不完整类型的指针 [英] dereferencing pointer to incomplete type for pcap_t structure

问题描述

我正在用 C 编写代码并使用 libpcap 库.我想查看 pcap_t 结构的字段，但总是有错误:

I am coding in C and using libpcap library. I want to see the fields of a pcap_t structure, but always have the error :

error: dereferencing pointer to incomplete type

最小代码如下:

#include <stdio.h>
#include <pcap/pcap.h>

int main()
{
    char errbuf[PCAP_ERRBUF_SIZE];
    pcap_t *handle;
    handle=pcap_open_live("eth0", 65535, 1, 1, errbuf);

    printf("Handle%d\n", handle->fd);

    pcap_close(handle);
}

编译完成:

gcc test.c -lpcap

根据http://www.opensource.apple.com/source/libpcap/libpcap-9/libpcap/pcap-int.h，pcap_t 结构确实有这个字段.libpcap通常是包含的，所以我完全不明白.

According to http://www.opensource.apple.com/source/libpcap/libpcap-9/libpcap/pcap-int.h, the pcap_t structure does have this field. The libpcap is normally included, so I do not understand at all.

谢谢！

结论: Olaf 似乎是对的:我有这个错误，因为我无法访问 pcap_t 结构.正如 Antti Haapala 所说，pcap_t 结构不是在 pcap/pcap.h 中定义的，而是在另一个文件中.

Conclusion: Olaf seems to be right : I have this error because I am not able to access the pcap_t structure. As Antti Haapala said, pcap_t struct is not defined in pcap/pcap.h but in another file.

我确实设法做我想做的事情，即使无法访问结构的字段.

I did manage to do what I wanted to do anyway, even without access to the fields of the structure.

问题已解决，感谢您的帮助！

Problem solved, thanks for your help !

推荐答案

pcap-int.h 代表 内部.但是，您没有在代码中包含此标头.

the -int in pcap-int.h stands for internal. However you're not including this header in your code.

注意pcap.h 本身不包含这个头文件，也不包含 struct pcap 的完整声明；而只是在 typedef 中使用前向声明:

Notice that pcap.h itself does not include this header, neither does it contain a full declaration of struct pcap; instead just using the forward declaration in typedef:

typedef struct pcap pcap_t;

试试吧:

#include <stdio.h>
#include <pcap/pcap-int.h>
#include <pcap/pcap.h>

int main()
{
    char errbuf[PCAP_ERRBUF_SIZE];
    pcap_t *handle;
    handle=pcap_open_live("eth0", 65535, 1, 1, errbuf);

    printf("Handle%d\n", handle->fd);

    pcap_close(handle);
}

<小时>

唉，这个内部头文件似乎没有安装在 Linux 和 Mac 上.对于一个非常丑陋的黑客，您可以尝试从链接中复制 pcap-int.h.

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