[addicted2sex]

So ? How If can example code

[OvidiuS]

Found in my pastes: http://pastebin.com/HAUQJn7c

[MrKoala]

Hey ovidius,

i found your code snippet too and tried to use it in an metamod plugin but unfortunately i cant get it working.. i am trying to install the hook in ServerActivate_Post and i am using the base offset for tfc linux servers but the MakeHook function aborts because of vtable being NULL

#ifdef _WIN32
#define VirtFuncTakeDamage      10
#elif __linux__
#define VirtFuncTakeDamage      12
#endif
 
#ifdef _WIN32
#define PrivateToEdict(pPrivate) (*(entvars_t **)((char*)pPrivate + 4))->pContainingEntity
#elif __linux__
#define PrivateToEdict(pPrivate) (*(entvars_t **)pPrivate)->pContainingEntity
#endif
 
void *pOrigFuncTakeDamage = NULL;
 
 
#ifdef _WIN32
int __fastcall HookTakeDamage(void *pthis, int i, entvars_t *pevInflictor, entvars_t *pevAttacker, float flDamage, int bitsDamage)
#elif __linux__
int HookTakeDamage(void *pthis, entvars_t *pevInflictor, entvars_t *pevAttacker, float flDamage, int bitsDamage)
#endif
{
        SERVER_PRINT("::TakeDamage prehook!\n");
 
#ifdef _WIN32
        int iOrigRet = reinterpret_cast<int(__fastcall *)(void *, int, entvars_t *, entvars_t *, float, int)>(pOrigFuncTakeDamage)(pthis, 0, pevInflictor, pevAttacker, flDamage, bitsDamage);
#elif __linux__
        int iOrigRet = reinterpret_cast<int(*)(void *, entvars_t *, entvars_t *, float, int)>(pOrigFuncTakeDamage)(pthis, pevInflictor, pevAttacker, flDamage, bitsDamage);
#endif
 
        SERVER_PRINT("::TakeDamage posthook!\n");
 
        return iOrigRet;
}
 
 
void MakeHookTakeDamage()
{
        edict_t *pEdict = CREATE_ENTITY();
 
        CALL_GAME_ENTITY(PLID, "func_breakable", &pEdict->v);
 
        if (pEdict->pvPrivateData == NULL)
        {
                REMOVE_ENTITY(pEdict);
 
                return;
        }
 
#ifdef _WIN32
        void **vtable = *((void***)((char*)pEdict->pvPrivateData));
#elif __linux__
        void **vtable = *((void***)(((char*)pEdict->pvPrivateData) + 0x470)); // 0x470 is the tfc base offset (is this correct for func_breakables too?)
#endif
 
 
 
        REMOVE_ENTITY(pEdict);
 
        if (vtable == NULL)
                return;
       
 
        int **ivtable = (int **)vtable;
 
        pOrigFuncTakeDamage = (void *)ivtable[VirtFuncTakeDamage];
 
#ifdef _WIN32
        DWORD OldFlags;
 
        VirtualProtect(&ivtable[VirtFuncTakeDamage], sizeof(int *), PAGE_READWRITE, &OldFlags);
#elif __linux__
        mprotect(&ivtable[VirtFuncTakeDamage], sizeof(int*), PROT_READ | PROT_WRITE);
#endif
 
        ivtable[VirtFuncTakeDamage] = (int *)HookTakeDamage;
}

Anyone has an idea why this could fail? I tried dumping pvPrivateData but it seems that its size is very small but i dont know why.
Would appreciate any help