我试图执行我自己的 c++ 新 & amp; 删除程序中的运算符 :

#include <stdio.h>
#include <stdlib.h>
#include <new>

using namespace std;

void *operator new(std::size_t size) throw(std::bad_alloc)
{
    printf("My new is called!
");
    return malloc(size);
}

void operator delete(void *ptr) throw ()
{
    printf("My delete is called!
");
    free(ptr);
}

void *operator new(std::size_t size, const std::nothrow_t&) throw()
{
    return malloc(size);
}

void operator delete(void *ptr, const std::nothrow_t&) throw()
{
    free(ptr);
}

void *operator new[](std::size_t size) throw(std::bad_alloc)
{
    return malloc(size);
}

void operator delete[](void *ptr) throw () 
{
    free(ptr);
}

void *operator new[](std::size_t size,
                     const std::nothrow_t&) throw()
{
    return malloc(size);
}

void operator delete[](void *ptr,
                       const std::nothrow_t&) throw()
{
    free(ptr);
}

class Object
{
public:
    Object() {}
    ~Object() {}

private:
    int a;
};

int main()
{
    Object* obj = new Object();
    if (obj)
        delete obj;

    return 0;
}

Then I find that, if the program is built out as: -- an exe, then my new/delete is called as expected -- but,, a shared-object, then symbols of new & delete is to be relocated, so in my env when this so is loaded by dlopen in another program then the new & delete will be mapped to another program s new & delete...

详细信息如铃声般...

1. 建立exe :

   gcc -m32 -c main.cpp gcc -m32 main.o -o main.exe

   $ ./main.exe My new is called! My delete is called!

   $ objdump -d main.exe 080484ac :
   80484ac: 55 push %ebp
   80484ad: 89 e5 mov %esp,%ebp
   80484af: 53 push %ebx
   80484b0: 83 ec 24 sub $0x24,%esp
   80484b3: 83 e4 f0 and $0xfffffff0,%esp
   80484b6: b8 00 00 00 00 mov $0x0,%eax
   80484bb: 83 c0 0f add $0xf,%eax
   80484be: 83 c0 0f add $0xf,%eax
   80484c1: c1 e8 04 shr $0x4,%eax
   80484c4: c1 e0 04 shl $0x4,%eax
   80484c7: 29 c4 sub %eax,%esp
   80484c9: c7 04 24 04 00 00 00 movl $0x4,(%esp)
   80484d0: e8 1f ff ff ff call 80483f4 <_Znwj> --> new: expected!!
   80484d5: 89 c3 mov %eax,%ebx
   80484d7: 89 1c 24 mov %ebx,(%esp)
   80484da: e8 35 00 00 00 call 8048514 <_ZN6ObjectC1Ev>
   80484df: 89 5d f8 mov %ebx,-0x8(%ebp)
   80484e2: 83 7d f8 00 cmpl $0x0,-0x8(%ebp)
   80484e6: 74 22 je 804850a
   80484e8: 8b 45 f8 mov -0x8(%ebp),%eax
   80484eb: 89 45 e8 mov %eax,-0x18(%ebp)
   80484ee: 83 7d e8 00 cmpl $0x0,-0x18(%ebp)
   80484f2: 74 16 je 804850a
   80484f4: 8b 45 e8 mov -0x18(%ebp),%eax
   80484f7: 89 04 24 mov %eax,(%esp)
   80484fa: e8 1b 00 00 00 call 804851a <_ZN6ObjectD1Ev>
   80484ff: 8b 45 e8 mov -0x18(%ebp),%eax
   8048502: 89 04 24 mov %eax,(%esp)
   8048505: e8 0a ff ff ff call 8048414 <_ZdlPv> --> delete: expected

2. 建立共同对象 :

   gcc -m32 -c main.cpp gcc --shared -m32 main.o -o main.so

   $ objdump -d main.so 000006d4 :
   6d4: 55 push %ebp
   6d5: 89 e5 mov %esp,%ebp
   6d7: 53 push %ebx
   6d8: 83 ec 24 sub $0x24,%esp
   6db: 83 e4 f0 and $0xfffffff0,%esp
   6de: b8 00 00 00 00 mov $0x0,%eax
   6e3: 83 c0 0f add $0xf,%eax
   6e6: 83 c0 0f add $0xf,%eax
   6e9: c1 e8 04 shr $0x4,%eax
   6ec: c1 e0 04 shl $0x4,%eax
   6ef: 29 c4 sub %eax,%esp
   6f1: c7 04 24 04 00 00 00 movl $0x4,(%esp)
   6f8: e8 fc ff ff ff call 6f9 ---> new: to be relocated, unexpected :(
   6fd: 89 c3 mov %eax,%ebx
   6ff: 89 1c 24 mov %ebx,(%esp)
   702: e8 fc ff ff ff call 703
   707: 89 5d f8 mov %ebx,-0x8(%ebp)
   70a: 83 7d f8 00 cmpl $0x0,-0x8(%ebp)
   70e: 74 22 je 732
   710: 8b 45 f8 mov -0x8(%ebp),%eax
   713: 89 45 e8 mov %eax,-0x18(%ebp)
   716: 83 7d e8 00 cmpl $0x0,-0x18(%ebp)
   71a: 74 16 je 732
   71c: 8b 45 e8 mov -0x18(%ebp),%eax
   71f: 89 04 24 mov %eax,(%esp)
   722: e8 fc ff ff ff call 723 ---> delete: to be relocated, unexpected :(
   727: 8b 45 e8 mov -0x18(%ebp),%eax
   72a: 89 04 24 mov %eax,(%esp)
   72d: e8 fc ff ff ff call 72e