Win32 CreateThread() Arguments Zero'ed? - c++

Question

Situation
Up until yesterday, my thread code was working fine. Now though, my thread arguments are being zeroed and moved as they are passed into the thread.
Relevant code in main.cpp
//First socket: UDP | Second Socket: TCP
std::pair<SOCKET, SOCKET> ServerSockets = Network::Operations::Server();
SOCKET UDPSocket = ServerSockets.first;
//Need to pass two arguments to the thread, when it only accepts one pointer. So create a struct and send the pointer.
ListenData UDPServ;
UDPServ.pNetwork = &Network;
UDPServ.LocalUDPSocket = UDPSocket;
//Set up the listener.
HANDLE UDPListener = Network::Operations::UDPListen(UDPServ);
At this stage UDPSocket is the correct value (e.g. 103), and pNetwork is also correct.
Relevant code in UDPListen()
static HANDLE UDPListen(ListenData UDPListenData)
{
HANDLE NetworkThread;
NetworkThread = CreateThread(
NULL, //Default security
0, //Default thread stack size
Network::Operations::Listen, //Thread function name
&UDPListenData, //Thread arguments
0, //Default creation flags
NULL);
//CloseHandle(NetworkThread);
return NetworkThread;
}
At this state, the values are as they should be.
Relevant code in Listen()
static DWORD WINAPI Listen(void *param)
{
ListenData *UDPServ = (ListenData*)param;
SOCKET Socket = UDPServ->LocalUDPSocket;
std::vector<Net> *Network = UDPServ->pNetwork;
Now however, UDPSocket is zero, and pNetwork is 103. This is a mystery.
The only code I've really changed is the code to initialise the server, which I modified to incorporate binding a TCP socket. The function used to return a single SOCKET but now returns an std::pair<SOCKET, SOCKET>.

Answer 1

you pass pointer to local data in stack - &UDPListenData - but this data is become undefined just after UDPListen return. you may be need code like
ListenData* UDPServ = new ListenData;
// init UDPServ
HANDLE NetworkThread = CreateThread(
NULL, //Default security
0, //Default thread stack size
Network::Operations::Listen, //Thread function name
UDPServ, //Thread arguments
0, //Default creation flags
NULL);
if (!NetworkThread) delete UDPServ;
//...
static DWORD WINAPI Listen(void *param)
{
ListenData *UDPServ = (ListenData*)param;
SOCKET Socket = UDPServ->LocalUDPSocket;
std::vector<Net> *Network = UDPServ->pNetwork;
//...
delete UDPServ;
}