奇怪的"未定义引用"错误

Question

所以我试图在使用C的Windows API上创建一个非常简单的抽象库.我制作了一个简单的Makefile,当我尝试使用Msys制作项目时,我得到了这个:

winapi.o: In function `get_client_pid':
(long path)/winapi.c:13: undefined reference to `GetExtendedTcpTable'
(long path)/winapi.c:31: undefined reference to `GetExtendedTcpTable'
collect2.exe: error: ld returned 1 exit status
make: *** [lib] Error 1

和get_client_pid()在winapi.c中定义为

#include <stdint.h>
#include <stdio.h>
#include <windows.h>
#include <Iphlpapi.h>

#define true 1
#define false 0


    uint32_t get_client_pid()
    {
        MIB_TCPTABLE_OWNER_PID *tcpTable;
        PDWORD tableSize;
        DWORD ret = GetExtendedTcpTable(tcpTable, 
                                        tableSize, 
                                        true, 
                                        2, 
                                        TCP_TABLE_OWNER_PID_ALL,
                                        0);

        if (ret == NO_ERROR) {
            printf("ERROR get_client_pid: No error with table size at 0?\n");
            return 0;
        }
        if (ret != ERROR_INSUFFICIENT_BUFFER) {
            printf("ERROR get_client_pid: No insufficient buffer with table size at 0?\n");
            return 0;
        }
        printf("TABLE SIZE %d\n", *tableSize);
        tcpTable = malloc(*tableSize);

        ret = GetExtendedTcpTable(  tcpTable,
                                    tableSize, 
                                    true,
                                    2,
                                    TCP_TABLE_OWNER_PID_ALL,
                                    0);

        if (ret != NO_ERROR) {
            printf("ERROR get_client_pid: GetExtendedTcpTable error: %d\n", ret);
            free(tcpTable);
            return 0;
        }

        int i;
        for (i = 0; i < tcpTable->dwNumEntries; i++) {
            MIB_TCPROW_OWNER_PID row = tcpTable->table[i];
            if (row.dwRemotePort == 0x208 && row.dwRemoteAddr == 0x100007F) {
                printf("FOUND PROCESS: %d\n", row.dwOwningPid);
                free(tcpTable);
                return row.dwOwningPid;
            }
        }

        free(tcpTable);
        return 0;
    }

由于这是一个链接器错误,我将添加我的makefile:

current_dir = $(shell pwd)

all: test

test: lib
    gcc -c -g tests.c
    gcc -o tests.exe tests.o -L$(current_dir) -lwinapi

lib:
    gcc -c -g winapi.c
    gcc -shared -o winapi.dll winapi.o -lIphlpapi -luser32

clean:
    rm *.o

我不得不说,我尝试了每个可能的地方插入"-lIphlpapi"以防链接以某种方式错误的顺序,但没有帮助.

Answer 1

MinGW在windef.h中定义WINVER为0x400(Windows NT)，这意味着Windows的一些较新的功能将不会链接。

#ifndef WINVER
#define WINVER 0x0400
/*
 * If you need Win32 API features newer the Win95 and WinNT then you must
 * define WINVER before including windows.h or any other method of including
 * the windef.h header.
 */
#endif

因此，在包含任何 Windows 标头之前，您需要将WINVER自己定义为目标 Windows 版本。

使用以下定义之一：

#define WINVER 0x0500 // Windows 2000
#define WINVER 0x0501 // Windows XP
#define WINVER 0x0502 // Windows Server 2003
#define WINVER 0x0600 // Windows Vista, Windows Server 2008
#define WINVER 0x0601 // Windows 7
#define WINVER 0x0602 // Windows 8
#define WINVER 0x0603 // Windows 8.1
#define WINVER 0x0A00 // Windows 10