c linux双重破坏静态变量.链接符号重叠

环境:linux x64,编译gcc 4.x

项目具有以下结构:

static library "slib"
-- inside this library, there is static object "sobj"

dynamic library "dlib"
-- links statically "slib"

executable "exe":
-- links "slib" statically
-- links "dlib" dynamically

在程序结束时,“sobj”被破坏了两次.这种行为是预期的,但它在相同的内存地址被破坏了两次,即在析构函数中是相同的“this”,因此存在双重破坏问题.
我认为是由于一些符号重叠.

那个冲突的解决方案是什么?也许一些链接选项?

这里是测试用例:

main_exe.cpp

#include <cstdlib>

#include "static_lib.h"
#include "dynamic_lib.h"

int main(int argc, char *argv[])
{
    stat_useStatic();
    din_useStatic();
    return EXIT_SUCCESS;
}

static_lib.h

#ifndef STATIC_LIB_H
#define STATIC_LIB_H

#include <cstdio>

void stat_useStatic();
struct CTest
{
    CTest(): status(isAlive)
    {
        printf("CTest() this=%d\n",this);
    }
    ~CTest()
    {
        printf("~CTest() this=%d, %s\n",this,status==isAlive?"is Alive":"is Dead");
        status=isDead;
    }
    void use()
    {
        printf("use\n");
    }
    static const int isAlive=12385423;
    static const int isDead=6543421;
    int status;

    static CTest test;
};

#endif

static_lib.cpp

#include "static_lib.h"

CTest CTest::test;

void stat_useStatic()
{
    CTest::test.use();
}

dynamic_lib.h

#ifndef DYNAMIC_LIB_H
#define DYNAMIC_LIB_H

#include "static_lib.h"

#ifdef WIN32
#define DLLExport __declspec(dllexport)
#else
#define DLLExport 
#endif
DLLExport void din_useStatic();


#endif

dynamic_lib.cpp

#include "dynamic_lib.h"

DLLExport void din_useStatic()
{
    CTest::test.use();
}

的CMakeLists.txt

project( StaticProblem )
cmake_minimum_required(VERSION 2.6)
if(WIN32)
else(WIN32)
    ADD_DEFINITIONS(-fPIC)
endif(WIN32)

ADD_LIBRARY( static_lib  STATIC static_lib.cpp static_lib.h)

ADD_LIBRARY( dynamic_lib SHARED dynamic_lib.cpp dynamic_lib.h)
TARGET_LINK_LIBRARIES( dynamic_lib static_lib )

ADD_EXECUTABLE( main_exe main_exe.cpp )
TARGET_LINK_LIBRARIES( main_exe static_lib dynamic_lib )

这个例子可以在Windows上工作,但在linux上是有问题的.
因为它在Windows上可以正常工作,解决方案应该是改变一些链接选项或类似的东西,但不能改变项目结构或不使用静态变量.

输出:

视窗

CTest() this=268472624
CTest() this=4231488
use
use
~CTest() this=4231488, is Alive
~CTest() this=268472624, is Alive

Linux的

CTest() this=6296204
CTest() this=6296204
use
use
~CTest() this=6296204, is Alive
~CTest() this=6296204, is Dead
好的,我找到了解决方案:

http://gcc.gnu.org/wiki/Visibility

例如如果改变

static CTest test;

__attribute__ ((visibility ("hidden"))) static CTest test;

问题会消失
Linux的:

CTest() this=-1646158468
CTest() this=6296196
use
use
~CTest() this=6296196, is Alive
~CTest() this=-1646158468, is Alive

修复前的nm输出为:

0000000000200dd4 B _ZN5CTest4testE

修复后:

0000000000200d7c b _ZN5CTest4testE

差异是将全局符号“B”改为局部符号“b”.

而不是将“attribute((visibility(”hidden“)))添加到符号中,可以使用编译器选项”-fvisibility = hidden“.该选项使gcc的行为更像Windows环境.

翻译自:https://stackoverflow.com/questions/6714046/c-linux-double-destruction-of-static-variable-linking-symbols-overlap

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