Windows: Win32 event for sigusr1 linux equivalence

Signed-off-by: John Howard <jhoward@microsoft.com>

system/events_windows.go

@@ -0,0 +1,83 @@
+package system
+
+// This file implements syscalls for Win32 events which are not implemented
+// in golang.
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+const (
+	EVENT_ALL_ACCESS    = 0x1F0003
+	EVENT_MODIFY_STATUS = 0x0002
+)
+
+var (
+	procCreateEvent = modkernel32.NewProc("CreateEventW")
+	procOpenEvent   = modkernel32.NewProc("OpenEventW")
+	procSetEvent    = modkernel32.NewProc("SetEvent")
+	procResetEvent  = modkernel32.NewProc("ResetEvent")
+	procPulseEvent  = modkernel32.NewProc("PulseEvent")
+)
+
+func CreateEvent(eventAttributes *syscall.SecurityAttributes, manualReset bool, initialState bool, name string) (handle syscall.Handle, err error) {
+	namep, _ := syscall.UTF16PtrFromString(name)
+	var _p1 uint32 = 0
+	if manualReset {
+		_p1 = 1
+	}
+	var _p2 uint32 = 0
+	if initialState {
+		_p2 = 1
+	}
+	r0, _, e1 := procCreateEvent.Call(uintptr(unsafe.Pointer(eventAttributes)), uintptr(_p1), uintptr(_p2), uintptr(unsafe.Pointer(namep)))
+	use(unsafe.Pointer(namep))
+	handle = syscall.Handle(r0)
+	if handle == syscall.InvalidHandle {
+		err = e1
+	}
+	return
+}
+
+func OpenEvent(desiredAccess uint32, inheritHandle bool, name string) (handle syscall.Handle, err error) {
+	namep, _ := syscall.UTF16PtrFromString(name)
+	var _p1 uint32 = 0
+	if inheritHandle {
+		_p1 = 1
+	}
+	r0, _, e1 := procOpenEvent.Call(uintptr(desiredAccess), uintptr(_p1), uintptr(unsafe.Pointer(namep)))
+	use(unsafe.Pointer(namep))
+	handle = syscall.Handle(r0)
+	if handle == syscall.InvalidHandle {
+		err = e1
+	}
+	return
+}
+
+func SetEvent(handle syscall.Handle) (err error) {
+	return setResetPulse(handle, procSetEvent)
+}
+
+func ResetEvent(handle syscall.Handle) (err error) {
+	return setResetPulse(handle, procResetEvent)
+}
+
+func PulseEvent(handle syscall.Handle) (err error) {
+	return setResetPulse(handle, procPulseEvent)
+}
+
+func setResetPulse(handle syscall.Handle, proc *syscall.LazyProc) (err error) {
+	r0, _, _ := proc.Call(uintptr(handle))
+	if r0 != 0 {
+		err = syscall.Errno(r0)
+	}
+	return
+}
+
+var temp unsafe.Pointer
+
+// use ensures a variable is kept alive without the GC freeing while still needed
+func use(p unsafe.Pointer) {
+	temp = p
+}