Demonstrates progblem in https://openradar.appspot.com/37363662

MIDIPacketNextTest.m

/* Compile this with:

clang -std=c99 -framework CoreMIDI -fed MIDIPacketNextTest.m

Run:

./a.out

*/

#import <CoreMIDI/CoreMIDI.h>

int main(int argc, char *argv[]) {
	
	MIDIPacket *packet1 = malloc(sizeof(MIDIPacket) + 5);
	packet1->timeStamp = 0;
	packet1->data[0] = 0x90; // Note on
	packet1->data[1] = 0x3c;
	packet1->data[2] = 0x40;
	packet1->data[3] = 0xd0; // Channel Pressure
	packet1->data[4] = 0x2a;
	packet1->length = 5;
	
	MIDIPacket *packet2 = malloc(sizeof(MIDIPacket) + 3);
	packet2->timeStamp = 1;
	packet2->data[0] = 0xb0; // Control Change
	packet2->data[1] = 0x1b;
	packet2->data[2] = 0x3f;
	packet2->length = 3;
	
	size_t listSize = sizeof(MIDIPacketList) + packet1->length + packet2->length;
	MIDIPacketList *pktlist = malloc(listSize);
	MIDIPacket *curPacket = MIDIPacketListInit(pktlist);
	curPacket = MIDIPacketListAdd(pktlist, listSize, curPacket, packet1->timeStamp, packet1->length, packet1->data);
	curPacket = MIDIPacketListAdd(pktlist, listSize, curPacket, packet2->timeStamp, packet2->length, packet2->data);
	
	// Get the first packet
	MIDIPacket *packet = (MIDIPacket *)pktlist->packet;
	for (int i = 0; i < pktlist->numPackets; i++) {
		
		// Ignore empty packets
		if (packet->length == 0) { // UBSan flags this for bad pointer alignment on x86_64
			printf("Packet was empty\n");
			packet = MIDIPacketNext(packet);
			continue;
		}
					
		packet = MIDIPacketNext(packet); 
	}
}