对同一文件中定义的函数的未定义引用

Question

我正在编译一个用gsoap生成的代码，我也应该编译/usr/share/gsoap/plugin/中gsoap提供的一些文件。

问题是在链接步骤中，我得到未定义的引用错误：

wsseapi.o: In function `soap_wsse_verify_Timestamp':
wsseapi.cpp:(.text+0xf64): undefined reference to `soap_wsa_sender_fault_subcode'

...同一个符号还有更多。

但是，该符号与使用它的soap_wsse_verify_Timestamp 在同一个文件中定义，当我使用 readelf 检查目标文件时，该符号已在其中定义：

$ readelf -Ws wsseapi.o |grep soap_wsa_sender_fault_subcode
   164: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND soap_wsa_sender_fault_subcode

这是原始文件中的函数定义：

/**
@fn int soap_wsse_verify_Timestamp(struct soap *soap)
@brief Verifies the Timestamp/Expires element against the current time.
@param soap context
@return SOAP_OK or SOAP_FAULT with wsse:FailedAuthentication fault

Sets wsse:FailedAuthentication fault if wsu:Timestamp is expired. The
SOAP_WSSE_CLKSKEW value is used as a margin to mitigate clock skew. Keeps
silent when no timestamp is supplied or no expiration date is included in the
wsu:Timestamp element.
*/
int
soap_wsse_verify_Timestamp(struct soap *soap)
{ _wsu__Timestamp *timestamp = soap_wsse_Timestamp(soap);
  DBGFUN("soap_wsse_verify_Timestamp");
  /* if we have a timestamp with an expiration date, check it */
  if (timestamp && timestamp->Expires)
  { time_t now = time(NULL), expired;
    soap_s2dateTime(soap, timestamp->Expires, &expired);
    if (expired + SOAP_WSSE_CLKSKEW <= now)
    { const char *code = soap_wsu__tTimestampFault2s(soap, wsu__MessageExpired);
      return soap_wsse_sender_fault_subcode(soap, code, "Message has expired", timestamp->Expires);
    }
  }
  return SOAP_OK;
}

和

/**
@fn int soap_wsse_sender_fault_subcode(struct soap *soap, const char *faultsubcode, const char *faultstring, const char *faultdetail)
@brief Sets sender SOAP Fault (sub)code for server fault response.
@param soap context
@param[in] faultsubcode sub code string
@param[in] faultstring fault string
@param[in] faultdetail detail string
@return SOAP_FAULT
*/
int
soap_wsse_sender_fault_subcode(struct soap *soap, const char *faultsubcode, const char *faultstring, const char *faultdetail)
{
#if defined(SOAP_WSA_2003) || defined(SOAP_WSA_2004) || defined(SOAP_WSA_200408) || defined(SOAP_WSA_2005)
  return soap_wsa_sender_fault_subcode(soap, faultsubcode, faultstring, faultdetail);
#else
  return soap_sender_fault_subcode(soap, faultsubcode, faultstring, faultdetail);
#endif
}

终于，

/**
@fn int soap_wsa_sender_fault_subcode(struct soap *soap, const char *faultsubcode, const char *faultstring, const char *faultdetail)
@brief Sets sender SOAP Fault (sub)code for server fault response.
@param soap context
@param[in] faultsubcode sub code string
@param[in] faultstring fault string
@param[in] faultdetail detail string
@return SOAP_FAULT
*/
int
soap_wsa_sender_fault_subcode(struct soap *soap, const char *faultsubcode, const char *faultstring, const char *faultdetail)
{ return soap_wsa_fault_subcode(soap, 1, faultsubcode, faultstring, faultdetail);
}

我的问题是，当符号在同一个文件中定义并且可以在同一个目标文件中找到时，如何会发生未定义的引用错误。

谢谢。

编辑： 这是包含在 cpp 文件顶部的头文件中的定义部分：

int soap_wsa_request(struct soap *soap, const char *id, const char *to, const char *action);
int soap_wsa_add_From(struct soap *soap, const char *endpoint);
int soap_wsa_add_NoReply(struct soap *soap);
int soap_wsa_add_ReplyTo(struct soap *soap, const char *endpoint);
int soap_wsa_add_FaultTo(struct soap *soap, const char *endpoint);
int soap_wsa_add_RelatesTo(struct soap *soap, const char *endpoint);
const char *soap_wsa_From(struct soap *soap);
const char *soap_wsa_ReplyTo(struct soap *soap);
const char *soap_wsa_FaultTo(struct soap *soap);
const char *soap_wsa_RelatesTo(struct soap *soap);

int soap_wsa_check(struct soap *soap);
int soap_wsa_reply(struct soap *soap, const char *id, const char *action);
int soap_wsa_fault_subcode(struct soap *soap, int flag, const char *faultsubcode, const char *faultstring, const char *faultdetail);
int soap_wsa_fault_subcode_action(struct soap *soap, int flag, const char *faultsubcode, const char *faultstring, const char *faultdetail, const char *action);
int soap_wsa_sender_fault_subcode(struct soap *soap, const char *faultsubcode, const char *faultstring, const char *faultdetail);
int soap_wsa_sender_fault_subcode_action(struct soap *soap, const char *faultsubcode, const char *faultstring, const char *faultdetail, const char *action);
int soap_wsa_receiver_fault_subcode(struct soap *soap, const char *faultsubcode, const char *faultstring, const char *faultdetail);
int soap_wsa_receiver_fault_subcode_action(struct soap *soap, const char *faultsubcode, const char *faultstring, const char *faultdetail, const char *action);
int soap_wsa_sender_fault(struct soap *soap, const char *faultstring, const char *faultdetail);
int soap_wsa_receiver_fault(struct soap *soap, const char *faultstring, const char *faultdetail);

更新： 问题似乎是由于 C++ 和 C 之间的链接问题（正如您在答案中看到的那样）。 gsoap 文件中存在一个悖论，因为在 C 源代码中使用了一个自动生成的头文件 wsseapi.c，它使用了 C++ 特性。如果我能解决这个问题，那么我认为编译和链接 wsseapi.c 也可以解决这个问题（正如 cmets 中的某人所提到的，缺失的函数实际上是在 C 源文件中定义的。）

但是，我放弃了整个解决方案，因为我找到了一种更简单的方法来使用 OpenCV 和 ffmpeg 从我的 IP 摄像机获取数据。所以我不会再测试了。

感谢大家的帮助。

Answer 1

我怀疑的问题是您正在尝试将一些 C 代码与 C++ 链接。与 C 相比，这可能会导致由于 C++ 中的名称被破坏而导致的链接错误。

要解决此类问题，您应该将从 C 源文件编译的函数包装在 extern 范围内：

extern "C" {
  int soap_wsa_sender_fault_subcode(struct soap *soap, const char *faultsubcode, const char *faultstring, const char *faultdetail);
}

这将防止封闭的函数被破坏，以便可以正确找到和链接它们在目标文件中的引用。您可以找到更多信息here。

Answer 2

出现此问题是因为您尝试将 C 代码与 C++ 代码链接。

假设你有wssapi.cwssapi.hmain.cpp。在您的main.cpp 中执行此操作

extern "C" {
    #include "wssapi.h"
}

而不仅仅是

#include "wssapi.h"