Autobuy problem resulting in crash

Huor

Ahoy @ all.

I think i found a problem within the hooking of autobuy and want to present a solution. But first wanted to ask if i am on the right way.

Fact is there is a division by zero implemented.

    Archetype::Equipment *eq = Archetype::GetEquipment ((*it4).iArchID);
    if (iRemHoldSize < (eq->fVolume * (*it4).iCount))
    {
      uint iNewCount = iRemHoldSize / (uint)eq->fVolume;
      if (!iNewCount)
      {
        //PrintUserCmdText (iClientID, L"Auto-Buy (%s): FAILED! Insufficient cargo space", (*it4).wscDescription.c_str ());
        continue;
      } 
      else
      {
        (*it4).iCount = iNewCount;
      }
    }

In case there are more items to missing than fitting into cargo. The number of items that can be bought until the cargo limit is reached is calculated. But if the volume of one item is smaller than 1 then the game crashes with a division by zero. Because there is a typecast from eq->fVolume to integer it will be a 0. The calculation should be:

uint iNewCount = (uint)(iRemHoldSize / eq->fVolume);

What ya say?

Huor

Just wanted to say that i have corrected it and now it seems not to crash anymore at this offset.

It seems normally its not common to define goods with less volume than 1 - but its possible and for some items it could make sense…

Huor

Gonna use that as i have seem to find another problem with the autobuy. Its again if the volume is less than 1.

Somewhen later the remaining holdsize is corrected with the following line:

int iCost = ((int)fPrice * (*it4).iCount);
....
iRemHoldSize -= ((int)eq->fVolume * (*it4).iCount);

But it should be more like, because making int of a float less than 1 makes it 0. Multiplying something with 0 is always 0 - hence the remaining cargo hold cannot be corrected properly.

int iCost = (int)(fPrice * (*it4).iCount);
...
iRemHoldSize -= (int)(eq->fVolume * (*it4).iCount);

Didnt tested it yet - but seems to be a reasonable bug…

Cannon

Thanks, I’ll update the flhook trunk shortly.

Do you want write access to SVN?

Huor

Not necessarily
BTW yesterday i had in mind to make an EnumCargo Routine that returns a float value of the remaining hold. Currently its always int (what is not wrong - but not accurate :)). Especially if you have items with a volume lower than 1.
Not really a bug - but maybe an improvement…

Huor

Found another issue which might lead to wrong autobuy. If a ship has no batts/bots defined it can happen that the autobuy buys nearly 4 billion items

here the code:

		foreach(lstCargo, CARGO_INFO, it)
		{
			AUTOBUY_CARTITEM aci;
			if((*it).iArchID == iNanobotsID) {
				aci.iArchID = iNanobotsID;
				aci.iCount = ship->iMaxNanobots - (*it).iCount;
				aci.wscDescription = L"Nanobots";
				lstCart.push_back(aci);
				bNanobotsFound = true;
			} else if((*it).iArchID == iShieldBatsID){
				aci.iArchID = iShieldBatsID;
				aci.iCount = ship->iMaxShieldBats - (*it).iCount;
				aci.wscDescription = L"Shield Batteries";
				lstCart.push_back(aci);
				bShieldBattsFound = true;
			}
		}

Should be changed to:

    foreach (lstCargo, CARGO_INFO, it)
    {
      AUTOBUY_CARTITEM aci;
      if (((*it).iArchID == iNanobotsID) && (ship->iMaxNanobots > 0))
      {
        aci.iArchID = iNanobotsID;
        aci.iCount = ship->iMaxNanobots - (*it).iCount;
        aci.wscDescription = L"Nanobots";
        lstCart.push_back (aci);
        bNanobotsFound = true;
      } 
      else if (((*it).iArchID == iShieldBatsID) && (ship->iMaxShieldBats > 0))
      {
        aci.iArchID = iShieldBatsID;
        aci.iCount = ship->iMaxShieldBats - (*it).iCount;
        aci.wscDescription = L"Shield Batteries";
        lstCart.push_back (aci);
        bShieldBattsFound = true;
      }
    }

    if ((!bNanobotsFound) && (ship->iMaxNanobots > 0))
    {
      // no nanos found -> add all
      AUTOBUY_CARTITEM aci;
      aci.iArchID = iNanobotsID;
      aci.iCount = ship->iMaxNanobots;
      aci.wscDescription = L"Nanobots";
      lstCart.push_back (aci);
    } 

    if ((!bShieldBattsFound) && (ship->iMaxShieldBats > 0))
    { 
      // no batts found -> add all
      AUTOBUY_CARTITEM aci;
      aci.iArchID = iShieldBatsID;
      aci.iCount = ship->iMaxShieldBats;
      aci.wscDescription = L"Shield Batteries";
      lstCart.push_back (aci);
    }
  }