[extension] Need help:kill player / apply damage to player

NeoTrantor · **Author**

Hi,

I'm trying to write my own extension to simulate a player killing another player.
I have a native to apply damage to an entity but the call to TakeDamage at the end of teh function causes the server to crash! Any help would be appreciated! I tried using virtual functions also but the result is the same.

Tested under linux only:
...

Code:

typedef void (*TakeDamageFunction)(const CTakeDamageInfo &);
TakeDamageFunction g_funcTakeDamage;

...

Code:

// hack: implementation of CTakeDamageInfo constructor

CTakeDamageInfo::CTakeDamageInfo(CBaseEntity *pInflictor, CBaseEntity *pAttacker, const Vector &damageForce, const Vector &damagePosition, float flDamage, int bitsDamageType, int iKillType, Vector *reportedPosition)
{
    m_hInflictor                = pInflictor;
    pAttacker                        = (pAttacker != NULL) ? pAttacker : pInflictor;
    m_vecDamageForce        = damageForce;
    m_vecDamagePosition    = damagePosition;
    m_flDamage                    = flDamage;
    m_bitsDamageType        = bitsDamageType;
    m_iDamageCustom            = iKillType;
    m_flBaseDamage            = BASEDAMAGE_NOT_SPECIFIED;

    if(reportedPosition != NULL)
        m_vecReportedPosition = *reportedPosition;

    m_flMaxDamage                = flDamage;
    m_iAmmoType                    = -1;
}

...

Code:

cell_t ApplyDamage(IPluginContext *pContext, const cell_t *params)
{
    int iParam=1;
    cell_t    nEntity                = params[iParam++];
    cell_t    nAttacker            = params[iParam++];
    cell_t    nInflictor        = params[iParam++];
    float        fDamage                = (float) params[iParam++];
    cell_t    nDamageType        = params[iParam++];

    CBaseEntity    *pEntity        = GetBaseEntityByIndex(nEntity);
    CBaseEntity *pAttacker    = GetBaseEntityByIndex(nAttacker);
    CBaseEntity *pInflictor    = GetBaseEntityByIndex(nInflictor);
    if(pEntity == NULL || pAttacker == NULL || pInflictor == NULL)
        return false;

    Vector vecOrigin(0.0f, 0.0f, 0.0f);
    CTakeDamageInfo TDI(pInflictor, pAttacker, vecOrigin, vecOrigin, fDamage, nDamageType, /*iKillType*/0);

#define USE_VFUNCTS
#ifdef USE_VFUNCTS
        void **this_ptr = *(void ***)&pEntity;
        void **vtable = *(void ***)pEntity;
        void *func = vtable[g_nOnTakeDamageOffset]; 

        class VfuncEmptyClass {};
        union {void (VfuncEmptyClass::*mfpnew)(CTakeDamageInfo const &);
        #ifndef __linux__
                void *addr;    } u;     u.addr = func;
        #else // GCC's member function pointers all contain a this pointer adjustor. You'd probably set it to 0 
                    struct {void *addr; intptr_t adjustor;} s; } u; u.s.addr = func; u.s.adjustor = 0;
        #endif
    
        (reinterpret_cast<VfuncEmptyClass*>(this_ptr)->*u.mfpnew)(TDI);
#else
    #ifdef WIN32
        g_funcTakeDamage(pEntity /*this*/, 0 /*dummy*/, TDI);
    #else
//        (g_funcTakeDamage)(pEntity, TDI);
        (g_funcTakeDamage)(TDI);
    #endif
#endif

    return true;
}

Full sourcecode of extension and test plugin: