runtime,internal/poll: move websocket handling out of the runtime on Windows

On Windows, the netpoll is currently coupled with the websocket usage
in the internal/poll package.

This CL moves the websocket handling out of the runtime and puts it into
the internal/poll package, which already contains most of the async I/O
logic for websockets.

This is a good refactor per se, as the Go runtime shouldn't know about
websockets. In addition, it will make it easier (in a future CL) to only
load ws2_32.dll when the Go program actually uses websockets.

Change-Id: Ic820872cf9bdbbf092505ed7f7504edb6687735e
Reviewed-on: https://go-review.googlesource.com/c/go/+/556936
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

3 files changed, 19 insertions, 6 deletions

diff --git a/src/internal/poll/fd_windows.go b/src/internal/poll/fd_windows.go
index 2095a6aa29..fe23d4b3d7 100644
--- a/src/internal/poll/fd_windows.go
+++ b/src/internal/poll/fd_windows.go
@@ -71,8 +71,6 @@ type operation struct {
 	// fields used by runtime.netpoll
 	runtimeCtx uintptr
 	mode       int32
-	errno      int32
-	qty        uint32
 
 	// fields used only by net package
 	fd     *FD
@@ -83,6 +81,7 @@ type operation struct {
 	rsan   int32
 	handle syscall.Handle
 	flags  uint32
+	qty    uint32
 	bufs   []syscall.WSABuf
 }
 
@@ -174,9 +173,9 @@ func execIO(o *operation, submit func(o *operation) error) (int, error) {
 	// Wait for our request to complete.
 	err = fd.pd.wait(int(o.mode), fd.isFile)
 	if err == nil {
+		err = windows.WSAGetOverlappedResult(fd.Sysfd, &o.o, &o.qty, false, &o.flags)
 		// All is good. Extract our IO results and return.
-		if o.errno != 0 {
-			err = syscall.Errno(o.errno)
+		if err != nil {
 			// More data available. Return back the size of received data.
 			if err == syscall.ERROR_MORE_DATA || err == windows.WSAEMSGSIZE {
 				return int(o.qty), err
@@ -202,8 +201,8 @@ func execIO(o *operation, submit func(o *operation) error) (int, error) {
 	}
 	// Wait for cancellation to complete.
 	fd.pd.waitCanceled(int(o.mode))
-	if o.errno != 0 {
-		err = syscall.Errno(o.errno)
+	err = windows.WSAGetOverlappedResult(fd.Sysfd, &o.o, &o.qty, false, &o.flags)
+	if err != nil {
 		if err == syscall.ERROR_OPERATION_ABORTED { // IO Canceled
 			err = netpollErr
 		}
diff --git a/src/internal/syscall/windows/syscall_windows.go b/src/internal/syscall/windows/syscall_windows.go
index d10e30cb68..a02c96c8f0 100644
--- a/src/internal/syscall/windows/syscall_windows.go
+++ b/src/internal/syscall/windows/syscall_windows.go
@@ -235,6 +235,7 @@ type WSAMsg struct {
 }
 
 //sys	WSASocket(af int32, typ int32, protocol int32, protinfo *syscall.WSAProtocolInfo, group uint32, flags uint32) (handle syscall.Handle, err error) [failretval==syscall.InvalidHandle] = ws2_32.WSASocketW
+//sys	WSAGetOverlappedResult(h syscall.Handle, o *syscall.Overlapped, bytes *uint32, wait bool, flags *uint32) (err error) = ws2_32.WSAGetOverlappedResult
 
 func loadWSASendRecvMsg() error {
 	sendRecvMsgFunc.once.Do(func() {
diff --git a/src/internal/syscall/windows/zsyscall_windows.go b/src/internal/syscall/windows/zsyscall_windows.go
index 931f157cf1..7d3cd37b92 100644
--- a/src/internal/syscall/windows/zsyscall_windows.go
+++ b/src/internal/syscall/windows/zsyscall_windows.go
@@ -86,6 +86,7 @@ var (
 	procCreateEnvironmentBlock            = moduserenv.NewProc("CreateEnvironmentBlock")
 	procDestroyEnvironmentBlock           = moduserenv.NewProc("DestroyEnvironmentBlock")
 	procGetProfilesDirectoryW             = moduserenv.NewProc("GetProfilesDirectoryW")
+	procWSAGetOverlappedResult            = modws2_32.NewProc("WSAGetOverlappedResult")
 	procWSASocketW                        = modws2_32.NewProc("WSASocketW")
 )
 
@@ -426,6 +427,18 @@ func GetProfilesDirectory(dir *uint16, dirLen *uint32) (err error) {
 	return
 }
 
+func WSAGetOverlappedResult(h syscall.Handle, o *syscall.Overlapped, bytes *uint32, wait bool, flags *uint32) (err error) {
+	var _p0 uint32
+	if wait {
+		_p0 = 1
+	}
+	r1, _, e1 := syscall.Syscall6(procWSAGetOverlappedResult.Addr(), 5, uintptr(h), uintptr(unsafe.Pointer(o)), uintptr(unsafe.Pointer(bytes)), uintptr(_p0), uintptr(unsafe.Pointer(flags)), 0)
+	if r1 == 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
 func WSASocket(af int32, typ int32, protocol int32, protinfo *syscall.WSAProtocolInfo, group uint32, flags uint32) (handle syscall.Handle, err error) {
 	r0, _, e1 := syscall.Syscall6(procWSASocketW.Addr(), 6, uintptr(af), uintptr(typ), uintptr(protocol), uintptr(unsafe.Pointer(protinfo)), uintptr(group), uintptr(flags))
 	handle = syscall.Handle(r0)