Make gVisor optional

gvisor.go

@@ -1,4 +1,4 @@
-//go:build !(no_gvisor || !(linux || windows || darwin))
+//go:build with_gvisor
 
 package tun
 
@@ -22,6 +22,8 @@ import (
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
+const WithGVisor = true
+
 const defaultNIC tcpip.NICID = 1
 
 type GVisor struct {
@@ -45,7 +47,7 @@ func NewGVisor(
 ) (Stack, error) {
 	gTun, isGTun := options.Tun.(GVisorTun)
 	if !isGTun {
-		return nil, ErrGVisorUnsupported
+		return nil, E.New("gVisor stack is unsupported on current platform")
 	}
 
 	return &GVisor{

gvisor_err.go

@@ -1,4 +1,4 @@
-//go:build !(no_gvisor || !(linux || windows || darwin))
+//go:build with_gvisor
 
 package tun
 

gvisor_log.go

@@ -1,4 +1,4 @@
-//go:build !(no_gvisor || !(linux || windows || darwin))
+//go:build with_gvisor
 
 package tun
 

gvisor_other.go

@@ -1,9 +0,0 @@
-//go:build !no_gvisor && !(linux || windows || darwin)
-
-package tun
-
-func NewGVisor(
-	options StackOptions,
-) (Stack, error) {
-	return nil, ErrGVisorUnsupported
-}

gvisor_stub.go

@@ -1,7 +1,13 @@
-//go:build no_gvisor
+//go:build !with_gvisor
 
 package tun
 
+import E "github.com/sagernet/sing/common/exceptions"
+
+const WithGVisor = false
+
+var ErrGVisorNotIncluded = E.New(`gVisor is not included in this build, rebuild with -tags with_gvisor`)
+
 func NewGVisor(
 	options StackOptions,
 ) (Stack, error) {

gvisor_udp.go

@@ -1,4 +1,4 @@
-//go:build !(no_gvisor || !(linux || windows || darwin))
+//go:build with_gvisor
 
 package tun
 

lwip_stub.go

@@ -2,8 +2,10 @@
 
 package tun
 
+import E "github.com/sagernet/sing/common/exceptions"
+
 func NewLWIP(
 	options StackOptions,
 ) (Stack, error) {
-	return nil, ErrLWIPNotIncluded
+	return nil, E.New(`LWIP is not included in this build, rebuild with -tags with_lwip`)
 }

stack.go

@@ -8,12 +8,6 @@ import (
 	"github.com/sagernet/sing/common/logger"
 )
 
-var (
-	ErrGVisorNotIncluded = E.New("gVisor is disabled in current build, try build without -tags `no_gvisor`")
-	ErrGVisorUnsupported = E.New("gVisor stack is unsupported on current platform")
-	ErrLWIPNotIncluded   = E.New("LWIP stack is disabled in current build, try build with -tags `with_lwip` and CGO_ENABLED=1")
-)
-
 type Stack interface {
 	Start() error
 	Close() error
@@ -37,7 +31,9 @@ func NewStack(
 	options StackOptions,
 ) (Stack, error) {
 	switch stack {
-	case "gvisor", "":
+	case "":
+		return NewSystem(options)
+	case "gvisor":
 		return NewGVisor(options)
 	case "system":
 		return NewSystem(options)

tun_darwin_gvisor.go

@@ -1,4 +1,4 @@
-//go:build !no_gvisor && darwin
+//go:build with_gvisor && darwin
 
 package tun
 

tun_linux_gvisor.go

@@ -1,4 +1,4 @@
-//go:build !no_gvisor && linux
+//go:build with_gvisor && linux
 
 package tun
 

tun_windows_gvisor.go

@@ -1,4 +1,4 @@
-//go:build !no_gvisor && windows
+//go:build with_gvisor && windows
 
 package tun