Use golang.org/x/sys/unix instead of syscall

The syscall package is deprecated and no longer updated as per
https://golang.org/pkg/syscall/. Use the golang.org/x/sys/unix package
instead, which also provides a wrapper for SYS_SETNS, so the syscall
number encoding depending on runtime.GOARCH can be dropped.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

go.mod

@@ -1,3 +1,5 @@
 module github.com/vishvananda/netns
 
 go 1.12
+
+require golang.org/x/sys v0.0.0-20200217220822-9197077df867

go.sum

@@ -0,0 +1,2 @@
+golang.org/x/sys v0.0.0-20200217220822-9197077df867 h1:JoRuNIf+rpHl+VhScRQQvzbHed86tKkqwPMV34T8myw=
+golang.org/x/sys v0.0.0-20200217220822-9197077df867/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

netns.go

@@ -10,7 +10,8 @@ package netns
 
 import (
 	"fmt"
-	"syscall"
+
+	"golang.org/x/sys/unix"
 )
 
 // NsHandle is a handle to a network namespace. It can be cast directly
@@ -24,23 +25,23 @@ func (ns NsHandle) Equal(other NsHandle) bool {
 	if ns == other {
 		return true
 	}
-	var s1, s2 syscall.Stat_t
-	if err := syscall.Fstat(int(ns), &s1); err != nil {
+	var s1, s2 unix.Stat_t
+	if err := unix.Fstat(int(ns), &s1); err != nil {
 		return false
 	}
-	if err := syscall.Fstat(int(other), &s2); err != nil {
+	if err := unix.Fstat(int(other), &s2); err != nil {
 		return false
 	}
 	return (s1.Dev == s2.Dev) && (s1.Ino == s2.Ino)
 }
 
 // String shows the file descriptor number and its dev and inode.
 func (ns NsHandle) String() string {
-	var s syscall.Stat_t
 	if ns == -1 {
 		return "NS(None)"
 	}
-	if err := syscall.Fstat(int(ns), &s); err != nil {
+	var s unix.Stat_t
+	if err := unix.Fstat(int(ns), &s); err != nil {
 		return fmt.Sprintf("NS(%d: unknown)", ns)
 	}
 	return fmt.Sprintf("NS(%d: %d, %d)", ns, s.Dev, s.Ino)
@@ -49,11 +50,11 @@ func (ns NsHandle) String() string {
 // UniqueId returns a string which uniquely identifies the namespace
 // associated with the network handle.
 func (ns NsHandle) UniqueId() string {
-	var s syscall.Stat_t
 	if ns == -1 {
 		return "NS(none)"
 	}
-	if err := syscall.Fstat(int(ns), &s); err != nil {
+	var s unix.Stat_t
+	if err := unix.Fstat(int(ns), &s); err != nil {
 		return "NS(unknown)"
 	}
 	return fmt.Sprintf("NS(%d:%d)", s.Dev, s.Ino)
@@ -67,7 +68,7 @@ func (ns NsHandle) IsOpen() bool {
 // Close closes the NsHandle and resets its file descriptor to -1.
 // It is not safe to use an NsHandle after Close() is called.
 func (ns *NsHandle) Close() error {
-	if err := syscall.Close(int(*ns)); err != nil {
+	if err := unix.Close(int(*ns)); err != nil {
 		return err
 	}
 	(*ns) = -1

netns_linux.go

@@ -7,26 +7,11 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"runtime"
 	"strconv"
 	"strings"
-	"syscall"
-)
 
-// SYS_SETNS syscall allows changing the namespace of the current process.
-var SYS_SETNS = map[string]uintptr{
-	"386":     346,
-	"amd64":   308,
-	"arm64":   268,
-	"arm":     375,
-	"mips":    4344,
-	"mipsle":  4344,
-	"mips64le":  4344,
-	"ppc64":   350,
-	"ppc64le": 350,
-	"riscv64": 268,
-	"s390x":   339,
-}[runtime.GOARCH]
+	"golang.org/x/sys/unix"
+)
 
 // Deprecated: use syscall pkg instead (go >= 1.5 needed).
 const (
@@ -41,11 +26,7 @@ const (
 // Setns sets namespace using syscall. Note that this should be a method
 // in syscall but it has not been added.
 func Setns(ns NsHandle, nstype int) (err error) {
-	_, _, e1 := syscall.Syscall(SYS_SETNS, uintptr(ns), uintptr(nstype), 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
+	return unix.Setns(int(ns), nstype)
 }
 
 // Set sets the current network namespace to the namespace represented
@@ -57,21 +38,21 @@ func Set(ns NsHandle) (err error) {
 // New creates a new network namespace, sets it as current and returns
 // a handle to it.
 func New() (ns NsHandle, err error) {
-	if err := syscall.Unshare(CLONE_NEWNET); err != nil {
+	if err := unix.Unshare(CLONE_NEWNET); err != nil {
 		return -1, err
 	}
 	return Get()
 }
 
 // Get gets a handle to the current threads network namespace.
 func Get() (NsHandle, error) {
-	return GetFromThread(os.Getpid(), syscall.Gettid())
+	return GetFromThread(os.Getpid(), unix.Gettid())
 }
 
 // GetFromPath gets a handle to a network namespace
 // identified by the path
 func GetFromPath(path string) (NsHandle, error) {
-	fd, err := syscall.Open(path, syscall.O_RDONLY, 0)
+	fd, err := unix.Open(path, unix.O_RDONLY, 0)
 	if err != nil {
 		return -1, err
 	}