我有以下三个项目:
现在,在Windows上构建这些内容一切正常。
在Linux上,我遇到了一个问题。
如何解决这个问题?
编辑:
下面是使用CMake的可编译示例。
CMakeLists.txt
Host
:一个可执行文件,导出一个全局变量(声明为extern)Plugin
:运行时库,由Host
加载并引用全局变量Tool
:一个可执行文件,链接到Plugin
并使用一些其功能。它不以任何方式引用全局变量。Tool
将仅链接到Plugin
的导出库,并且不会尝试解析全局变量。在Linux上,我遇到了一个问题。
Tool
尝试链接到Plugin
的.so库(因为没有导出库),并找到Host
中对全局变量的引用,但无法解析。如何解决这个问题?
编辑:
下面是使用CMake的可编译示例。
CMakeLists.txt
SET(CMAKE_RUNTIME_OUTPUT_DIRECTORY_DEBUG "${CMAKE_CURRENT_SOURCE_DIR}/bin")
SET(CMAKE_LIBRARY_OUTPUT_DIRECTORY_DEBUG "${CMAKE_CURRENT_SOURCE_DIR}/bin")
SET(CMAKE_POSITION_INDEPENDENT_CODE ON)
ADD_SUBDIRECTORY(Host)
ADD_SUBDIRECTORY(Plugin)
ADD_SUBDIRECTORY(Tool)
Host/Host.h
#ifndef HOST_H
#define HOST_H
#ifdef _MSC_VER
#ifdef COMPILE_HOST
#define HOST_EXPORT __declspec(dllexport)
#else
#define HOST_EXPORT __declspec(dllimport)
#endif
#else
#define HOST_EXPORT
#endif
class HOST_EXPORT Host
{
public:
int getAnswer();
};
extern HOST_EXPORT Host g_host;
#endif
Host/Host.cpp
#include "Host.h"
#include "../Plugin/Plugin.h"
#include <iostream>
Host g_host;
int Host::getAnswer()
{
return 42;
}
int main()
{
std::cout << g_host.getAnswer() << std::endl;
// load plugin and use it
}
Host/CMakeLists.txt
PROJECT(Host)
ADD_EXECUTABLE(Host Host.cpp Host.h)
ADD_DEFINITIONS(-DCOMPILE_HOST)
SET_TARGET_PROPERTIES(Host PROPERTIES ENABLE_EXPORTS ON)
Plugin/Plugin.h
#ifndef PLUGIN_H
#define PLUGIN_H
class Plugin
{
public:
Plugin();
};
#endif
Plugin/Plugin.cpp
#include "Plugin.h"
#include "../Host/Host.h"
#include <iostream>
Plugin::Plugin()
{
std::cout << g_host.getAnswer() << std::endl;
}
Plugin/PluginFunc.h
#ifndef PLUGINFUNC_H
#define PLUGINFUNC_H
#ifdef _MSC_VER
#define PLUGIN_EXPORT __declspec(dllexport)
#else
#define PLUGIN_EXPORT
#endif
namespace plug
{
int PLUGIN_EXPORT getRandomNumber();
}
#endif
Plugin/PluginFunc.cpp
#include "PluginFunc.h"
int plug::getRandomNumber()
{
return 4;
}
Plugin/CMakeLists.txt
PROJECT(Plugin)
ADD_LIBRARY(Plugin SHARED Plugin.cpp Plugin.h PluginFunc.cpp PluginFunc.h)
TARGET_LINK_LIBRARIES(Plugin Host)
Tool/Tool.cpp
#include "../Plugin/PluginFunc.h"
#include <iostream>
int main()
{
std::cout << plug::getRandomNumber() << std::endl;
}
Tool/CMakeLists.txt
PROJECT(Tool)
ADD_EXECUTABLE(Tool Tool.cpp)
TARGET_LINK_LIBRARIES(Tool Plugin)
在Windows上,它能够构建和运行。Host.exe 显示“42”,Tool.exe 显示“4”。
在Linux上,我遇到了以下链接错误:
usr@debian64:~/vbox/testlink/build$ make
Scanning dependencies of target Host
[ 25%] Building CXX object Host/CMakeFiles/Host.dir/Host.o
Linking CXX executable Host
[ 25%] Built target Host
Scanning dependencies of target Plugin
[ 50%] Building CXX object Plugin/CMakeFiles/Plugin.dir/Plugin.o
[ 75%] Building CXX object Plugin/CMakeFiles/Plugin.dir/PluginFunc.o
Linking CXX shared library libPlugin.so
[ 75%] Built target Plugin
Scanning dependencies of target Tool
[100%] Building CXX object Tool/CMakeFiles/Tool.dir/Tool.o
Linking CXX executable Tool
../Plugin/libPlugin.so: undefined reference to `Host::getAnswer()'
../Plugin/libPlugin.so: undefined reference to `g_host'
collect2: error: ld returned 1 exit status
make[2]: *** [Tool/Tool] Error 1
make[1]: *** [Tool/CMakeFiles/Tool.dir/all] Error 2
make: *** [all] Error 2