[Bug 31507] midiInOpen x64 crash due to callback address 32-bit truncation

http://bugs.winehq.org/show_bug.cgi?id=31507

--- Comment #5 from Nikolay Sivov  2012-08-19 20:10:17 CDT ---
Hi, George.

I think I found a problem you're seeing, pointer truncation happens in wine
sound driver at MIDI_NotifyClient():

---
static void MIDI_NotifyClient(UINT wDevID, WORD wMsg,
                  DWORD_PTR dwParam1, DWORD_PTR dwParam2)
{
    DWORD         dwCallBack;
...
    case MIM_OPEN:
    case MIM_CLOSE:
    case MIM_DATA:
    case MIM_LONGDATA:
    case MIM_ERROR:
    case MIM_LONGERROR:
    case MIM_MOREDATA:
    if (wDevID > MIDM_NumDevs) return;

dwCallBack = MidiInDev[wDevID].midiDesc.dwCallback;
    uFlags = MidiInDev[wDevID].wFlags;
    hDev = MidiInDev[wDevID].midiDesc.hMidi;
    dwInstance = MidiInDev[wDevID].midiDesc.dwInstance;
    break;
...
    DriverCallback(dwCallBack, uFlags, hDev, wMsg, dwInstance, dwParam1,
dwParam2);
}
---

So it gets truncated with a cast to DWORD it seems. You could easily check that
modifying local dwCallBack variable to be DWORD_PTR, and you need to modify a
driver you're using - winealsa or wineoss.

I'll send a patch for that later today if this change helps you.