From 0e80d729a3e163fe5ea25d2d4199cf84eb9a2f1d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=B8=96=E7=95=8C?= <i@sekai.icu>
Date: Thu, 15 Sep 2022 11:19:31 +0800
Subject: [PATCH] Make gVisor optional

---
 gvisor.go             |  6 ++++--
 gvisor_err.go         |  2 +-
 gvisor_log.go         |  2 +-
 gvisor_other.go       |  9 ---------
 gvisor_stub.go        |  8 +++++++-
 gvisor_udp.go         |  2 +-
 lwip_stub.go          |  4 +++-
 stack.go              | 10 +++-------
 tun_darwin_gvisor.go  |  2 +-
 tun_linux_gvisor.go   |  2 +-
 tun_windows_gvisor.go |  2 +-
 11 files changed, 23 insertions(+), 26 deletions(-)
 delete mode 100644 gvisor_other.go

diff --git a/gvisor.go b/gvisor.go
index eac1a18..9292002 100644
--- a/gvisor.go
+++ b/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{
diff --git a/gvisor_err.go b/gvisor_err.go
index d2f016a..775a7f7 100644
--- a/gvisor_err.go
+++ b/gvisor_err.go
@@ -1,4 +1,4 @@
-//go:build !(no_gvisor || !(linux || windows || darwin))
+//go:build with_gvisor
 
 package tun
 
diff --git a/gvisor_log.go b/gvisor_log.go
index fc46be1..3649cbd 100644
--- a/gvisor_log.go
+++ b/gvisor_log.go
@@ -1,4 +1,4 @@
-//go:build !(no_gvisor || !(linux || windows || darwin))
+//go:build with_gvisor
 
 package tun
 
diff --git a/gvisor_other.go b/gvisor_other.go
deleted file mode 100644
index e30e891..0000000
--- a/gvisor_other.go
+++ /dev/null
@@ -1,9 +0,0 @@
-//go:build !no_gvisor && !(linux || windows || darwin)
-
-package tun
-
-func NewGVisor(
-	options StackOptions,
-) (Stack, error) {
-	return nil, ErrGVisorUnsupported
-}
diff --git a/gvisor_stub.go b/gvisor_stub.go
index 2a022c3..bd380f4 100644
--- a/gvisor_stub.go
+++ b/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) {
diff --git a/gvisor_udp.go b/gvisor_udp.go
index 87837ff..7424c65 100644
--- a/gvisor_udp.go
+++ b/gvisor_udp.go
@@ -1,4 +1,4 @@
-//go:build !(no_gvisor || !(linux || windows || darwin))
+//go:build with_gvisor
 
 package tun
 
diff --git a/lwip_stub.go b/lwip_stub.go
index 1810329..403a45e 100644
--- a/lwip_stub.go
+++ b/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`)
 }
diff --git a/stack.go b/stack.go
index e92b838..1eed543 100644
--- a/stack.go
+++ b/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)
diff --git a/tun_darwin_gvisor.go b/tun_darwin_gvisor.go
index 0d5c4a4..b57bf2c 100644
--- a/tun_darwin_gvisor.go
+++ b/tun_darwin_gvisor.go
@@ -1,4 +1,4 @@
-//go:build !no_gvisor && darwin
+//go:build with_gvisor && darwin
 
 package tun
 
diff --git a/tun_linux_gvisor.go b/tun_linux_gvisor.go
index 4dfe587..4386220 100644
--- a/tun_linux_gvisor.go
+++ b/tun_linux_gvisor.go
@@ -1,4 +1,4 @@
-//go:build !no_gvisor && linux
+//go:build with_gvisor && linux
 
 package tun
 
diff --git a/tun_windows_gvisor.go b/tun_windows_gvisor.go
index fd27621..11fe041 100644
--- a/tun_windows_gvisor.go
+++ b/tun_windows_gvisor.go
@@ -1,4 +1,4 @@
-//go:build !no_gvisor && windows
+//go:build with_gvisor && windows
 
 package tun