一段应急的C++对象检查代码

一个JNI项目，偶发离奇崩溃，怀疑是野指针类的问题。开address sanitizer本地难复现，测试版开as太卡，大部分测试机还是6、7的系统。

还好大部分都对象都派生自引用计数的基类，于是按fail-fast的思路憋出了以下代码，在加减引用和怀疑区域手动插桩检查。

附上代码，无关部分做了简化

#include <type_traits>
#include <stdio.h>
#include <assert.h>

#define LOG(...) do { fprintf(stderr, __VA_ARGS__); fflush(stderr); } while (false)

class Object
{
public:
    Object()
        : _falgs(0xcafecafe)
    {
    }
    virtual ~Object()
    {
        _falgs = 0xdeaddead;
    }
    // is not strict but help avoid most of error
    bool isValid() const
    {
        return static_cast<const void *>(this) && (_falgs == 0xcafecafe);
    }

private:
    int _falgs;
};

class ObjectCheck
{
public:
    template <typename T>
    static bool Check(T obj)
    {
        return doCheck<T>(obj);
    }

    template <typename T>
    static bool CheckNullable(T obj)
    {
        return obj == nullptr || doCheck<T>(obj);
    }

private:
    template <typename T>
    static bool doCheck(typename std::enable_if<std::is_base_of<Object, typename std::remove_pointer<T>::type>::value && !std::is_void<typename std::remove_pointer<T>::type>::value, T>::type obj)
    {
        LOG("dynamic_cast && isValid %p %p ", dynamic_cast<T>(reinterpret_cast<Object*>(obj)), obj);
        return (obj == dynamic_cast<T>(reinterpret_cast<Object*>(obj)) && obj->isValid());
    }

    template <typename T>
    static bool doCheck(typename std::enable_if<!std::is_base_of<Object, typename std::remove_pointer<T>::type>::value && std::is_polymorphic<typename std::remove_pointer<T>::type>::value, T>::type obj)
    {
        LOG("dynamic_cast %p %p ", dynamic_cast<T>(obj), obj);
        return (obj == dynamic_cast<T>(obj));
    }

    template <typename T>
    static bool doCheck(typename std::enable_if<std::is_void<typename std::remove_pointer<T>::type>::value, T>::type obj)
    {
        LOG("static_cast void* ");
        return (obj == static_cast<void *>(obj));
    }
};

class Dummy
{
public:
    virtual ~Dummy() = default;
    int dummy;
};
class SubObject : public Object
{
public:
    int dummy;
};

int main()
{
    void *t1 = nullptr;
    Object *t2 = nullptr;
    Dummy *t3 = nullptr;
    SubObject *t4 = nullptr;
    Object *t5 = new Object();
    Dummy *t6 = new Dummy();
    SubObject *t7 = new SubObject();
    SubObject *t8 = reinterpret_cast<SubObject *>(t6);
    SubObject *t9 = reinterpret_cast<SubObject *>(t5);
    SubObject *t10 = new SubObject();
    delete t10;

    LOG("result %d \n", ObjectCheck::CheckNullable(t1));
    LOG("result %d \n", ObjectCheck::CheckNullable(t2));
    LOG("result %d \n", ObjectCheck::CheckNullable(t3));
    LOG("result %d \n", ObjectCheck::CheckNullable(t4));
    LOG("result %d \n", ObjectCheck::Check(t5));
    LOG("result %d \n", ObjectCheck::Check(t6));
    LOG("result %d \n", ObjectCheck::Check(t7));
    LOG("result %d \n", ObjectCheck::Check(t8));
    LOG("result %d \n", ObjectCheck::Check(t9));
    LOG("result %d \n", ObjectCheck::Check(t10));
}

输出

result 1 
result 1 
result 1 
result 1 
dynamic_cast && isValid 0x7fca1cc02b40 0x7fca1cc02b40 result 1 
dynamic_cast 0x7fca1cc02b50 0x7fca1cc02b50 result 1 
dynamic_cast && isValid 0x7fca1cc02b60 0x7fca1cc02b60 result 1 
dynamic_cast && isValid 0x0 0x7fca1cc02b50 result 0 
dynamic_cast && isValid 0x0 0x7fca1cc02b40 result 0 
[1]    30935 segmentation fault  ./a.out