那些遇到过的问题

在C++中重复静态变量初始化

Con*_*ord 5 c++ linux static dlopen

我使用类"MyClass"构建一个共享库"libMyLibrary.so",该类包含"MyClass"类型的静态变量.然后我构建了一个可执行文件"MyLibraryTest",我链接到"libMyLibrary.so".主程序使用"dlopen"动态加载作为参数给出的".so".

在构建时,库和可执行文件在目录中生成,例如"buildDir/bin".然后我将库安装到"installDir/lib",将可执行文件安装到"installDir/bin"(从可执行文件中删除运行时路径).

当我用LD_LIBRARY_PATH = buildDir运行"buildDir/MyLibraryTest buildDir/MyLibrary.so"时,一切都很好.

但是当我使用LD_LIBRARY_PATH = installDir/lib运行"buildDir/MyLibraryTest installDir/lib/MyLibrary.so"时,会发生一件非常奇怪的事情: - 静态变量的构造函数被调用两次(一次在dlopen之前,一次在dlopen期间) - 最后执行时,析构函数被调用两次,这导致崩溃.

这是我的代码:

MyClass.h

#ifndef _MyClass_h__
#define _MyClass_h__

#include <string>

class MyClass
{
private:
    static MyClass myStaticObjOfMyClass;
public:
    MyClass(const std::string& name, bool trace);
    virtual ~MyClass();
private:
    std::string myName;
    bool myTrace;
};

#endif // _MyClass_h__
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MyClass.cpp

#include "MyClass.h"
#include <iostream>

MyClass MyClass::myStaticObjOfMyClass("myStaticObjOfMyClass", true);

MyClass::MyClass(const std::string& name, bool trace) : myName(name), myTrace(trace)
{
    if (myTrace) std::cout << "MyClass::MyClass(name=" << myName << ", address=" << this << ")" << std::endl;
}

MyClass::~MyClass()
{
    if (myTrace) std::cout << "MyClass::~MyClass(name=" << myName << ", address=" << this << ")" << std::endl;
}
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MyLibraryTest.cpp

#include <MyClass.h>
#include <iostream>
#include <string>
#include <dlfcn.h>

int main(int argc, char* argv[])
{
    const std::string sharedLibraryFullName((const char*)argv[1]);

    // std::cout << "Try to load library " << sharedLibraryFullName << std::endl;
    void* handle = NULL;
    std::cout << "dlopen(" << sharedLibraryFullName << ")" << std::endl;
    handle = dlopen(sharedLibraryFullName.c_str(), RTLD_LAZY | RTLD_GLOBAL);
    if (handle == NULL)
    {
        std::cout << "ERROR : Could not load shared library " << sharedLibraryFullName << std::endl;
    }
    else
    {
        std::cout << "OK, shared library " << sharedLibraryFullName << " is now loaded" << std::endl;
    }
}
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以下是编译和链接命令:

/usr/local/bin/g++  -DMyLibrary_DEFINED -DMyLibrary_EXPORTS  -O3 -DNDEBUG -fPIC   -o CMakeFiles/MyLibrary.dir/MyClass.cpp.o -c MyClass.cpp
/usr/local/bin/g++ -fPIC -O3 -DNDEBUG  -shared -Wl,-soname,libMyLibrary.so -o ../bin/libMyLibrary.so CMakeFiles/MyLibrary.dir/MyClass.cpp.o
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最后这里是第二种情况(静态变量的重复初始化):

MyClass::MyClass(name=myStaticObjOfMyClass, address=0x7fa710cabb40)
dlopen(/tmp/Install/MyLibraryTest/lib/libMyLibrary.so)
MyClass::MyClass(name=myStaticObjOfMyClass, address=0x7fa710cabb40)
OK, shared library /tmp/Install/MyLibraryTest/lib/libMyLibrary.so is now loaded
MyClass::~MyClass(name=myStaticObjOfMyClass, address=0x7fa710cabb40)
MyClass::~MyClass(name=??ObjOfMyClass, address=0x7fa710cabb40)
*** glibc detected *** /tmp/Build/MyLibraryTest/Release/bin/MyLibraryTest: double free or corruption (fasttop): 0x0000000000cfb330 ***
======= Backtrace: =========
/lib64/libc.so.6[0x322f275dee]
/lib64/libc.so.6[0x322f278c3d]
/lib64/libc.so.6(__cxa_finalize+0x9d)[0x322f235d2d]
/tmp/Build/MyLibraryTest/Release/bin/libMyLibrary.so(+0x1076)[0x7fa710aab076]
======= Memory map: ========
00400000-00402000 r-xp 00000000 fd:00 1325638                            /tmp/Build/MyLibraryTest/Release/bin/MyLibraryTest
00601000-00602000 rw-p 00001000 fd:00 1325638                            /tmp/Build/MyLibraryTest/Release/bin/MyLibraryTest
00ce9000-00d1b000 rw-p 00000000 00:00 0                                  [heap]
322ee00000-322ee20000 r-xp 00000000 fd:00 545634                         /lib64/ld-2.12.so
322f020000-322f021000 r--p 00020000 fd:00 545634                         /lib64/ld-2.12.so
322f021000-322f022000 rw-p 00021000 fd:00 545634                         /lib64/ld-2.12.so
322f022000-322f023000 rw-p 00000000 00:00 0 
322f200000-322f38a000 r-xp 00000000 fd:00 545642                         /lib64/libc-2.12.so
322f38a000-322f58a000 ---p 0018a000 fd:00 545642                         /lib64/libc-2.12.so
322f58a000-322f58e000 r--p 0018a000 fd:00 545642                         /lib64/libc-2.12.so
322f58e000-322f590000 rw-p 0018e000 fd:00 545642                         /lib64/libc-2.12.so
322f590000-322f594000 rw-p 00000000 00:00 0 
322fa00000-322fa02000 r-xp 00000000 fd:00 545709                         /lib64/libdl-2.12.so
322fa02000-322fc02000 ---p 00002000 fd:00 545709                         /lib64/libdl-2.12.so
322fc02000-322fc03000 r--p 00002000 fd:00 545709                         /lib64/libdl-2.12.so
322fc03000-322fc04000 rw-p 00003000 fd:00 545709                         /lib64/libdl-2.12.so
3230600000-3230683000 r-xp 00000000 fd:00 545684                         /lib64/libm-2.12.so
3230683000-3230882000 ---p 00083000 fd:00 545684                         /lib64/libm-2.12.so
3230882000-3230883000 r--p 00082000 fd:00 545684                         /lib64/libm-2.12.so
3230883000-3230884000 rw-p 00083000 fd:00 545684                         /lib64/libm-2.12.so
7fa70c000000-7fa70c021000 rw-p 00000000 00:00 0 
7fa70c021000-7fa710000000 ---p 00000000 00:00 0 
7fa7102e7000-7fa7102e9000 r-xp 00000000 fd:00 1320668                    /tmp/Install/MyLibraryTest/lib/libMyLibrary.so
7fa7102e9000-7fa7104e8000 ---p 00002000 fd:00 1320668                    /tmp/Install/MyLibraryTest/lib/libMyLibrary.so
7fa7104e8000-7fa7104e9000 rw-p 00001000 fd:00 1320668                    /tmp/Install/MyLibraryTest/lib/libMyLibrary.so
7fa7104e9000-7fa7104ed000 rw-p 00000000 00:00 0 
7fa7104ed000-7fa710503000 r-xp 00000000 fd:00 708322                     /usr/local/lib64/libgcc_s.so.1
7fa710503000-7fa710702000 ---p 00016000 fd:00 708322                     /usr/local/lib64/libgcc_s.so.1
7fa710702000-7fa710703000 rw-p 00015000 fd:00 708322                     /usr/local/lib64/libgcc_s.so.1
7fa710703000-7fa710704000 rw-p 00000000 00:00 0 
7fa710704000-7fa710883000 r-xp 00000000 fd:00 708539                     /usr/local/lib64/libstdc++.so.6.0.21
7fa710883000-7fa710a83000 ---p 0017f000 fd:00 708539                     /usr/local/lib64/libstdc++.so.6.0.21
7fa710a83000-7fa710a8d000 r--p 0017f000 fd:00 708539                     /usr/local/lib64/libstdc++.so.6.0.21
7fa710a8d000-7fa710a8f000 rw-p 00189000 fd:00 708539                     /usr/local/lib64/libstdc++.so.6.0.21
7fa710a8f000-7fa710a94000 rw-p 00000000 00:00 0 
7fa710aa8000-7fa710aaa000 rw-p 00000000 00:00 0 
7fa710aaa000-7fa710aac000 r-xp 00000000 fd:00 1325633                    /tmp/Build/MyLibraryTest/Release/bin/libMyLibrary.so
7fa710aac000-7fa710cab000 ---p 00002000 fd:00 1325633                    /tmp/Build/MyLibraryTest/Release/bin/libMyLibrary.so
7fa710cab000-7fa710cac000 rw-p 00001000 fd:00 1325633                    /tmp/Build/MyLibraryTest/Release/bin/libMyLibrary.so
7fa710cac000-7fa710cad000 rw-p 00000000 00:00 0 
7fff2fc61000-7fff2fc76000 rw-p 00000000 00:00 0                          [stack]
7fff2fde5000-7fff2fde6000 r-xp 00000000 00:00 0                          [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]
./test_dyn_libs.sh: line 21: 30880 Abandon                 (core dumped) ${BuildDir}/MyLibraryTest ${InstallDir}/lib/libMyLibrary.so
--- End of tests
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任何帮助将不胜感激 !!!

Con*_*ord 0

谢谢大家的答案。正如托德所说，我忘记包含 MyLibraryTest 的链接命令。这里是 ：

/usr/local/bin/g++  -O3 -DNDEBUG  -rdynamic CMakeFiles/MyLibraryTest.dir/MyLibraryTest.cpp.o  -o ../bin/MyLibraryTest -Wl,-rpath,/tmp/Build/MyLibraryTest/Release/bin: ../bin/libMyLibrary.so -ldl
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该问题与 RPATH 有关。如果我不再使用 -Wl,-rpath 选项，测试工作正常！

我使用 CMake 来构建我的项目，并发现了这个： https: //cmake.org/Wiki/CMake_RPATH_handling。现在，我在 CMakeLists.txt 中使用以下命令，这会删除 -Wl,-rpath 链接选项。

set (CMAKE_SKIP_RPATH ON)
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