AlliedModders - [Solved] Call a function by the pointer from FunctionTable

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- - Solved Call a function by the pointer from FunctionTable (https://forums.alliedmods.net/showthread.php?t=322445)

Call a function by the pointer from FunctionTable

I have these functions from datamaps:

DEFINE_THINKFUNC( Detonate )

Code:

CBaseCSGrenadeProjectile - hegrenade_projectile

- InitializeSpawnFromWorld (Offset 0) (Input)(0 Bytes) - InitializeSpawnFromWorld

- CBaseCSGrenadeProjectileDangerSoundThink (Offset 0) (FunctionTable)(0 Bytes)

- m_hThrower (Offset 1292) (Save)(4 Bytes)

- m_bIsLive (Offset 1265) (Save)(1 Bytes)

- m_DmgRadius (Offset 1268) (Save)(4 Bytes)

- CBaseGrenadeSmoke (Offset 0) (FunctionTable)(0 Bytes)

- CBaseGrenadeExplodeTouch (Offset 0) (FunctionTable)(0 Bytes)

- CBaseGrenadeDetonateUse (Offset 0) (FunctionTable)(0 Bytes)

- CBaseGrenadePreDetonate (Offset 0) (FunctionTable)(0 Bytes)

- CBaseGrenadeDetonate (Offset 0) (FunctionTable)(0 Bytes)

I get a void* from CBaseGrenadeDetonate (and it's not nullptr), is there a way to call the function using the pointer?

PHP Code:


		
			
DEFINE_THINKFUNC( Detonate ),

virtual void Detonate( void );

I tried to do it like this, but it crashes the server:

PHP Code:


		
			
typedef void (*Detonate_pointer)();



void* pointer = ...



((Detonate_pointer)pointer ())();

PHP Code:


		
			
void* pointer = ...

CBaseEntity* ptr = ...

reinterpret_cast< void(*)(CBaseEntity*) > (pointer ) (ptr );

UPD:
I got inputfunc_t field value from typedescription_t of the "CBaseGrenadeDetonate", I gues that should be the correct funcion pointer, but have no idea ho I can call it

Re: Call a function by the pointer from FunctionTable

Here is my solution:

PHP Code:


		
			
#define EXTRACT_VOID_FUNCTIONPTR(x)        (*(void **)(&(x)))

void *UTIL_FunctionFromName( datamap_t *pMap, const char *pName )
{
    while ( pMap )
    {
        for ( int i = 0; i < pMap->dataNumFields; i++ )
        {
            Assert( sizeof(pMap->dataDesc[i].inputFunc) == sizeof(void *) );

            if ( pMap->dataDesc[i].flags & FTYPEDESC_FUNCTIONTABLE )
            {
                if ( FStrEq( pName, pMap->dataDesc[i].fieldName ) )
                {
                    return EXTRACT_VOID_FUNCTIONPTR(pMap->dataDesc[i].inputFunc);
                }
            }
        }
        pMap = pMap->baseMap;
    }

    Msg( "Failed to find function %s\n", pName );

    return NULL;
}

typedef void (CBaseEntity::*VALVE_BASEPTR)(void);
typedef void (CBaseEntity::*VALVE_ENTITYFUNCPTR)(CBaseEntity *pOther);

VALVE_BASEPTR CBaseGrenade::func_Detonate = nullptr;
VALVE_ENTITYFUNCPTR CBaseGrenade::func_ExplodeTouch = nullptr;

void CBaseGrenade::detonate()
{
    if(func_Detonate != nullptr)
        return;

    void *ptr = UTIL_FunctionFromName( GetDataDescMap_Real(), "CBaseGrenadeDetonate");
    if(!ptr)
        return;

    memcpy(&func_Detonate, &ptr, sizeof(void *));
    (getBaseEntity()->*func_Detonate)(); //getBaseEntity() returns CBaseEntity*
}

For GetDataDescMap_Real use standard offset from core.games "GetDataDescMap"
It seams to be the only way to detonate grenades without delays and dealing with signatures.