CTD using GetSpellNameByID

[Zoydburg]

This happens when you try to use GetSpellNameByID() with an epmty spell Gem

First-chance exception at 0x01717cb7 (MQ2Main.dll) in eqgame.exe: 0xC0000005: Access violation reading location 0x4152a7d4.

> MQ2Main.dll!GetSpellNameByID(unsigned long dwSpellID=4294967295) Line 866 C++

dwSpellID 4294967295 unsigned long

MQ2Utilities.cpp

Code: Select all

PCHAR GetSpellNameByID(DWORD dwSpellID)
{
    PSPELL pSpell = NULL;
    if (ppSpellMgr == NULL) return "Unknown Spell";
    pSpell =  &(*((PSPELLMGR)pSpellMgr)->Spells[dwSpellID]);
    if (pSpell != NULL) {
>>        if (pSpell->Name != NULL) {
            if (pSpell->Name[0]!='\0') {
                return pSpell->Name;
            }
        }
    }
    return "Unknown Spell";
}

[Zoydburg]

Also get a CTD using GetSpellByID() and a blank spell slot

First-chance exception at 0x0340121c in eqgame.exe: 0xC0000005: Access violation reading location 0x00000210.

> MQ2SpellSet.dll!0340121c()

03401218 jmp 0340121C
0340121A xor eax,eax
>0340121C mov edx,dword ptr [eax+210h]
03401222 push esi
03401223 push edx
03401224 lea eax,[esp+1018h]

code that calls GetSpellByID()

Code: Select all

VOID MemSpellSet(PSPAWNINFO pChar, PCHAR szLine)
{
   for (i=1; i<=9; i++)
   {
	  PSPELL pSpell=GetSpellByID(GetCharInfo()->MemorizedSpells[i-1]);

		sprintf(szMsg,"Spell %s goes in Gem %d",pSpell->Name, i);
		WriteChatColor(szMsg,USERCOLOR_CHAT_CHANNEL);
   }
}

[Amadeus]

What's the syntax of the macro you're using to get this error? I'm not sure I'm following on how you're creating this bug.

[Zoydburg]

Not a macro its a plugin and anytime I use either the GetSpellByID() or GetSpellNameByID() and the spell slot I am searching is blank it CTD's

Code: Select all

GetCharInfo()->MemorizedSpells[i-1]

Returns a -1 if the spell slot it is searching is empty

I tried

Code: Select all

VOID MemSpellSet(PSPAWNINFO pChar, PCHAR szLine)
{
   for (i=1; i<=9; i++)
   {
     PSPELL pSpell=GetSpellByID(GetCharInfo()->MemorizedSpells[i-1]);

      sprintf(szMsg,"Spell %s goes in Gem %d",pSpell->Name, i);
      WriteChatColor(szMsg,USERCOLOR_CHAT_CHANNEL);
   }
}

and

Code: Select all

VOID MemSpellSet(PSPAWNINFO pChar, PCHAR szLine)
{
   CHAR szSpellName[MAX_STRING] = {0};
   for (i=1; i<=9; i++)
   {
     sprintf(szSpellname,"%s",GetSpellNameByID(GetCharInfo()->MemorizedSpells[i-1]));

      sprintf(szMsg,"Spell %s goes in Gem %d",szSpellName, i);
      WriteChatColor(szMsg,USERCOLOR_CHAT_CHANNEL);
   }
}

Posible fix for GetSpellNameByID, I have not tested it but looking at the code this looks like it will fix it

Code: Select all

PCHAR GetSpellNameByID(DWORD dwSpellID)
{
    if(dwSpellID == -1) return "Unknown Spell";
    PSPELL pSpell = NULL;
    if (ppSpellMgr == NULL) return "Unknown Spell";
    pSpell =  &(*((PSPELLMGR)pSpellMgr)->Spells[dwSpellID]);
    if (pSpell != NULL) {
        if (pSpell->Name != NULL) {
            if (pSpell->Name[0]!='\0') {
                return pSpell->Name;
            }
        }
    }
    return "Unknown Spell";
}

[dont_know_at_all]

Not a macro its a plugin and anytime I use either the GetSpellByID() or GetSpellNameByID() and the spell slot I am searching is blank it CTD's

Well, duh. Check for a blank one.

[Zoydburg]

Yes DKAA I did that, but it still should not CTD if someone does not do that it should return Unknown Spell or NULL or something.

[dont_know_at_all]

Please use macros and not plugins.

[Zoydburg]

I was trying to update Digitalxero's MQ2SpellSet when I found this BUG. Though it looks like he updated it lastnight at the same time I was playing with it.

[dont_know_at_all]

Your crash is not a bug.

If you are going to call functions with the wrong data, you're going to get crashes. We have no way of determining if the spell id is valid or not. YOU have to check MemorizedSpells before you use it. It's not guarranteed to be a valid spell ID.

[Amadeus]

Yes, a plugin has to be coded correctly and has to have the check in the plugin's code. The plugin should verify that the spell gem and/or the spell id is valid before it calls the function.