IOCP alertable wait (buggy)

iocp.c

#define _WIN32_WINNT _WIN32_WINNT_WIN10
#include <windows.h>

#include <stdio.h>

OVERLAPPED overlapped = {};

VOID
timer_proc(LPVOID arg, DWORD low, DWORD high)
{
	HANDLE cp = (HANDLE)arg;
	ULONG_PTR key = 42;
	
	printf("%s: posting completion: key = %lu, &overlapped = %p\n",
		__func__, (ULONG)key, &overlapped);
	PostQueuedCompletionStatus(cp, 0, 42, &overlapped);
}

int
main(int argc, char** argv)
{
	HANDLE cp;
	HANDLE timer;
	OVERLAPPED_ENTRY oes[10];
	ULONG noes = sizeof(oes) / sizeof(oes[0]);
	ULONG noes_out = 0;
	ULONG i;
	BOOL result;

	cp = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 1);
	if (cp == NULL) {
		printf("CreateIoCompletionPort(cp) -> %lu\n", GetLastError());
		return EXIT_FAILURE;
	}
	
	timer = CreateWaitableTimer(NULL, FALSE, NULL);
	if (timer == NULL) {
		printf("CreateWaitableTimer() -> %lu\n", GetLastError());
		return EXIT_FAILURE;
	}

	LARGE_INTEGER timeout;
	timeout.QuadPart = -10ll * 1000ll * 1000ll; /* 1 sec (relative) */
	if (!SetWaitableTimer(timer, &timeout, 0, timer_proc, cp, FALSE)) {
		printf("SetWaitableTimer() -> %lu\n", GetLastError());
		return EXIT_FAILURE;
	}

	printf("%s: waiting on IOCP\n", __func__);
	result = GetQueuedCompletionStatusEx(
		cp, oes, noes, &noes_out, INFINITE, TRUE);
	if (!result) {
		printf("GetQueuedCompletionStatus() -> %lu\n", GetLastError());
		/* Not exiting, let's see the result anyway. */
	}

	printf("%s: %lu I/O request completed\n", __func__, noes_out);
	for (i = 0; i < noes_out; i++) {
		printf("I/O result %lu: key = %lu, &overlapped = %p\n",
			i, (ULONG)oes[i].lpCompletionKey, oes[i].lpOverlapped);
	}
	return EXIT_SUCCESS;
}