fix core dump due to memory corruption

[a8jan]

I was getting quite often core dumps when starting emulator, e.g:

DBG: [Screen] Windowed mode: 1440x1300 -> viewport: 1440x1280
DBG: [Sound] Initialized device to 44100Hz/8bit with 1024B (2048B) buffer
malloc(): unaligned tcache chunk detected
Aborted (core dumped)

finding the cause with help of valgrind:

...
DBG: [Sound] Initialized device to 44100Hz/8bit with 1024B (2048B) buffer
==47796== Invalid write of size 8
==47796==    at 0x48527F7: memset (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==47796==    by 0x14D5AB: Joy4004482::Joy4004482(IifGPIO*, TSettings::SetJoystick*) (Joy4004482.cpp:36)
==47796==    by 0x12C414: TEmulator::SetComputerModel(bool, int, unsigned char*) (Emulator.cpp:1396)
==47796==    by 0x1290E4: TEmulator::ProcessSettings(unsigned char) (Emulator.cpp:372)
==47796==    by 0x11CA2F: main (GPMD85emu.cpp:106)
==47796==  Address 0x125d4310 is 0 bytes after a block of size 144 alloc'd
==47796==    at 0x4849013: operator new(unsigned long) (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==47796==    by 0x12C3F0: TEmulator::SetComputerModel(bool, int, unsigned char*) (Emulator.cpp:1396)
==47796==    by 0x1290E4: TEmulator::ProcessSettings(unsigned char) (Emulator.cpp:372)
==47796==    by 0x11CA2F: main (GPMD85emu.cpp:106)
==47796== 
==47796== Invalid write of size 8
...

To fix it, I changed the way the joy[2] was initialized in Joy4004482 constructor.

-jan

[mborik]

Amazing catch @a8jan
I'm getting faults too, but I won't be able to trace it properly on my M1 Mac.
Now I'm on vacation, so I can't test it.

[mborik]

Q: What's difference between nullptr and NULL?

[mborik]

oh, I see, it's new C++11 keyword. But I think that we could put NULL macro here a update globals.h to work with nullptr (I'll change it when I come back home).

[mborik]

Do you think, that we could set pio and settings same way?

So that throw (plus include) we could omit...? 🤔

[a8jan]

yes, I think we can reduce the constructor code to just initializer

Joy4004482::Joy4004482(IifGPIO *pio, TSettings::SetJoystick* settings) :
	pio(pio),
	settings(settings),
	joy{{ NULL, NULL, false, 0 }, { NULL, NULL, false, 0 }},
	joyCnt(0),
	sameDev(false)
{
}

[mborik]

Confirmed that it works: #25 (comment)