windows: add FlushConsoleInputBuffer and GetNumberOfConsoleInputEvents

This adds syscall wrappers for FlushConsoleInputBuffer and GetNumberOfConsoleInputEvents on Windows.

Change-Id: I2365aebc42a57f83cfc951e10520270e1f3e0606
GitHub-Last-Rev: 1f711a5f3c2b09b6bc74160f0fc7c54a0247be14
GitHub-Pull-Request: golang/sys#264
Reviewed-on: https://go-review.googlesource.com/c/sys/+/704715
Reviewed-by: Mark Freeman <markfreeman@google.com>
Auto-Submit: Sean Liao <sean@liao.dev>
Reviewed-by: Quim Muntal <quimmuntal@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

windows/syscall_windows.go

@@ -321,6 +321,8 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 //sys	SetConsoleOutputCP(cp uint32) (err error) = kernel32.SetConsoleOutputCP
 //sys	WriteConsole(console Handle, buf *uint16, towrite uint32, written *uint32, reserved *byte) (err error) = kernel32.WriteConsoleW
 //sys	ReadConsole(console Handle, buf *uint16, toread uint32, read *uint32, inputControl *byte) (err error) = kernel32.ReadConsoleW
+//sys	GetNumberOfConsoleInputEvents(console Handle, numevents *uint32) (err error) = kernel32.GetNumberOfConsoleInputEvents
+//sys	FlushConsoleInputBuffer(console Handle) (err error) = kernel32.FlushConsoleInputBuffer
 //sys	resizePseudoConsole(pconsole Handle, size uint32) (hr error) = kernel32.ResizePseudoConsole
 //sys	CreateToolhelp32Snapshot(flags uint32, processId uint32) (handle Handle, err error) [failretval==InvalidHandle] = kernel32.CreateToolhelp32Snapshot
 //sys	Module32First(snapshot Handle, moduleEntry *ModuleEntry32) (err error) = kernel32.Module32FirstW

windows/zsyscall_windows.go

@@ -238,6 +238,7 @@ var (
 	procFindResourceW                                        = modkernel32.NewProc("FindResourceW")
 	procFindVolumeClose                                      = modkernel32.NewProc("FindVolumeClose")
 	procFindVolumeMountPointClose                            = modkernel32.NewProc("FindVolumeMountPointClose")
+	procFlushConsoleInputBuffer                              = modkernel32.NewProc("FlushConsoleInputBuffer")
 	procFlushFileBuffers                                     = modkernel32.NewProc("FlushFileBuffers")
 	procFlushViewOfFile                                      = modkernel32.NewProc("FlushViewOfFile")
 	procFormatMessageW                                       = modkernel32.NewProc("FormatMessageW")
@@ -284,6 +285,7 @@ var (
 	procGetNamedPipeHandleStateW                             = modkernel32.NewProc("GetNamedPipeHandleStateW")
 	procGetNamedPipeInfo                                     = modkernel32.NewProc("GetNamedPipeInfo")
 	procGetNamedPipeServerProcessId                          = modkernel32.NewProc("GetNamedPipeServerProcessId")
+	procGetNumberOfConsoleInputEvents                        = modkernel32.NewProc("GetNumberOfConsoleInputEvents")
 	procGetOverlappedResult                                  = modkernel32.NewProc("GetOverlappedResult")
 	procGetPriorityClass                                     = modkernel32.NewProc("GetPriorityClass")
 	procGetProcAddress                                       = modkernel32.NewProc("GetProcAddress")
@@ -2111,6 +2113,14 @@ func FindVolumeMountPointClose(findVolumeMountPoint Handle) (err error) {
 	return
 }
 
+func FlushConsoleInputBuffer(console Handle) (err error) {
+	r1, _, e1 := syscall.SyscallN(procFlushConsoleInputBuffer.Addr(), uintptr(console))
+	if r1 == 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
 func FlushFileBuffers(handle Handle) (err error) {
 	r1, _, e1 := syscall.SyscallN(procFlushFileBuffers.Addr(), uintptr(handle))
 	if r1 == 0 {
@@ -2481,6 +2491,14 @@ func GetNamedPipeServerProcessId(pipe Handle, serverProcessID *uint32) (err erro
 	return
 }
 
+func GetNumberOfConsoleInputEvents(console Handle, numevents *uint32) (err error) {
+	r1, _, e1 := syscall.SyscallN(procGetNumberOfConsoleInputEvents.Addr(), uintptr(console), uintptr(unsafe.Pointer(numevents)))
+	if r1 == 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
 func GetOverlappedResult(handle Handle, overlapped *Overlapped, done *uint32, wait bool) (err error) {
 	var _p0 uint32
 	if wait {