net: remove sysSocket fallback for Windows 7

`syscall.ForkLock` is not used in `syscall.StartProcess` since
CL 288297, so using it in `sysSocket` makes no sense. This CL
goes a little bit further and removes the `sysSocket` fallback for
Windows 7, since it is not supported since go 1.21 (#57003).

Updates #60942

Change-Id: If14a0d94742f1b80af994f9f69938701ee41b402
Reviewed-on: https://go-review.googlesource.com/c/go/+/506136
Reviewed-by: Heschi Kreinick <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Run-TryBot: Quim Muntal <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Alex Brainman <[email protected]>

Author: qmuntal

src/net/hook_windows.go

@@ -14,7 +14,6 @@ var (
 	testHookDialChannel = func() { time.Sleep(time.Millisecond) } // see golang.org/issue/5349
 
 	// Placeholders for socket system calls.
-	socketFunc    func(int, int, int) (syscall.Handle, error)                                                 = syscall.Socket
 	wsaSocketFunc func(int32, int32, int32, *syscall.WSAProtocolInfo, uint32, uint32) (syscall.Handle, error) = windows.WSASocket
 	connectFunc   func(syscall.Handle, syscall.Sockaddr) error                                                = syscall.Connect
 	listenFunc    func(syscall.Handle, int) error                                                             = syscall.Listen

src/net/internal/socktest/main_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !js && !plan9 && !wasip1
+//go:build !js && !plan9 && !wasip1 && !windows
 
 package socktest_test
 

src/net/internal/socktest/main_windows_test.go

@@ -9,38 +9,6 @@ import (
 	"syscall"
 )
 
-// Socket wraps syscall.Socket.
-func (sw *Switch) Socket(family, sotype, proto int) (s syscall.Handle, err error) {
-	sw.once.Do(sw.init)
-
-	so := &Status{Cookie: cookie(family, sotype, proto)}
-	sw.fmu.RLock()
-	f, _ := sw.fltab[FilterSocket]
-	sw.fmu.RUnlock()
-
-	af, err := f.apply(so)
-	if err != nil {
-		return syscall.InvalidHandle, err
-	}
-	s, so.Err = syscall.Socket(family, sotype, proto)
-	if err = af.apply(so); err != nil {
-		if so.Err == nil {
-			syscall.Closesocket(s)
-		}
-		return syscall.InvalidHandle, err
-	}
-
-	sw.smu.Lock()
-	defer sw.smu.Unlock()
-	if so.Err != nil {
-		sw.stats.getLocked(so.Cookie).OpenFailed++
-		return syscall.InvalidHandle, so.Err
-	}
-	nso := sw.addLocked(s, family, sotype, proto)
-	sw.stats.getLocked(nso.Cookie).Opened++
-	return s, nil
-}
-
 // WSASocket wraps syscall.WSASocket.
 func (sw *Switch) WSASocket(family, sotype, proto int32, protinfo *syscall.WSAProtocolInfo, group uint32, flags uint32) (s syscall.Handle, err error) {
 	sw.once.Do(sw.init)

src/net/internal/socktest/sys_windows.go

@@ -8,7 +8,6 @@ import "internal/poll"
 
 var (
 	// Placeholders for saving original socket system calls.
-	origSocket      = socketFunc
 	origWSASocket   = wsaSocketFunc
 	origClosesocket = poll.CloseFunc
 	origConnect     = connectFunc
@@ -18,7 +17,6 @@ var (
 )
 
 func installTestHooks() {
-	socketFunc = sw.Socket
 	wsaSocketFunc = sw.WSASocket
 	poll.CloseFunc = sw.Closesocket
 	connectFunc = sw.Connect
@@ -28,7 +26,6 @@ func installTestHooks() {
 }
 
 func uninstallTestHooks() {
-	socketFunc = origSocket
 	wsaSocketFunc = origWSASocket
 	poll.CloseFunc = origClosesocket
 	connectFunc = origConnect

src/net/main_windows_test.go

@@ -19,21 +19,6 @@ func maxListenerBacklog() int {
 func sysSocket(family, sotype, proto int) (syscall.Handle, error) {
 	s, err := wsaSocketFunc(int32(family), int32(sotype), int32(proto),
 		nil, 0, windows.WSA_FLAG_OVERLAPPED|windows.WSA_FLAG_NO_HANDLE_INHERIT)
-	if err == nil {
-		return s, nil
-	}
-	// WSA_FLAG_NO_HANDLE_INHERIT flag is not supported on some
-	// old versions of Windows, see
-	// https://msdn.microsoft.com/en-us/library/windows/desktop/ms742212(v=vs.85).aspx
-	// for details. Just use syscall.Socket, if windows.WSASocket failed.
-
-	// See ../syscall/exec_unix.go for description of ForkLock.
-	syscall.ForkLock.RLock()
-	s, err = socketFunc(family, sotype, proto)
-	if err == nil {
-		syscall.CloseOnExec(s)
-	}
-	syscall.ForkLock.RUnlock()
 	if err != nil {
 		return syscall.InvalidHandle, os.NewSyscallError("socket", err)
 	}

src/net/sock_windows.go

@@ -14,6 +14,7 @@ import (
 	"unsafe"
 )
 
+// ForkLock is not used on Windows.
 var ForkLock sync.RWMutex
 
 // EscapeArg rewrites command line argument s as prescribed