libgo: update to Go1.14beta1

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/214297

36 files changed, 589 insertions, 151 deletions

diff --git a/libgo/go/syscall/dirent.go b/libgo/go/syscall/dirent.go
index 58c34c3..5726449 100644
--- a/libgo/go/syscall/dirent.go
+++ b/libgo/go/syscall/dirent.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.
 
-// +build aix darwin dragonfly freebsd hurd js,wasm linux nacl netbsd openbsd solaris
+// +build aix darwin dragonfly freebsd hurd js,wasm linux netbsd openbsd solaris
 
 package syscall
 
diff --git a/libgo/go/syscall/dirent_bsd_test.go b/libgo/go/syscall/dirent_test.go
index 43b667b..f631533 100644
--- a/libgo/go/syscall/dirent_bsd_test.go
+++ b/libgo/go/syscall/dirent_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.
 
-// +build darwin dragonfly freebsd netbsd openbsd
+// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
 
 package syscall_test
 
diff --git a/libgo/go/syscall/env_plan9.go b/libgo/go/syscall/env_plan9.go
index 9a8a837..e403a25 100644
--- a/libgo/go/syscall/env_plan9.go
+++ b/libgo/go/syscall/env_plan9.go
@@ -74,7 +74,21 @@ func Setenv(key, value string) error {
 }
 
 func Clearenv() {
-	RawSyscall(SYS_RFORK, RFCENVG, 0, 0)
+	// Creating a new environment group using rfork(RFCENVG) can race
+	// with access to files in /env (e.g. from Setenv or Getenv).
+	// Remove all environment variables in current environment group instead.
+	fd, err := open("/env", O_RDONLY)
+	if err != nil {
+		return
+	}
+	defer Close(fd)
+	files, err := readdirnames(fd)
+	if err != nil {
+		return
+	}
+	for _, key := range files {
+		Remove("/env/" + key)
+	}
 }
 
 func Unsetenv(key string) error {
diff --git a/libgo/go/syscall/env_unix.go b/libgo/go/syscall/env_unix.go
index c22af18..3564f7f 100644
--- a/libgo/go/syscall/env_unix.go
+++ b/libgo/go/syscall/env_unix.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.
 
-// +build aix darwin dragonfly freebsd hurd js,wasm linux nacl netbsd openbsd solaris
+// +build aix darwin dragonfly freebsd hurd js,wasm linux netbsd openbsd solaris
 
 // Unix environment variables.
 
diff --git a/libgo/go/syscall/exec_linux_test.go b/libgo/go/syscall/exec_linux_test.go
index 7bd3910..1a44f04 100644
--- a/libgo/go/syscall/exec_linux_test.go
+++ b/libgo/go/syscall/exec_linux_test.go
@@ -34,6 +34,14 @@ func isLXC() bool {
 }
 
 func skipInContainer(t *testing.T) {
+	// TODO: the callers of this func are using this func to skip
+	// tests when running as some sort of "fake root" that's uid 0
+	// but lacks certain Linux capabilities. Most of the Go builds
+	// run in privileged containers, though, where root is much
+	// closer (if not identical) to the real root. We should test
+	// for what we need exactly (which capabilities are active?),
+	// instead of just assuming "docker == bad". Then we'd get more test
+	// coverage on a bunch of builders too.
 	if isDocker() {
 		t.Skip("skip this test in Docker container")
 	}
@@ -42,6 +50,18 @@ func skipInContainer(t *testing.T) {
 	}
 }
 
+func skipNoUserNamespaces(t *testing.T) {
+	if _, err := os.Stat("/proc/self/ns/user"); err != nil {
+		if os.IsNotExist(err) {
+			t.Skip("kernel doesn't support user namespaces")
+		}
+		if os.IsPermission(err) {
+			t.Skip("unable to test user namespaces due to permissions")
+		}
+		t.Fatalf("Failed to stat /proc/self/ns/user: %v", err)
+	}
+}
+
 func skipUnprivilegedUserClone(t *testing.T) {
 	// Skip the test if the sysctl that prevents unprivileged user
 	// from creating user namespaces is enabled.
@@ -64,15 +84,7 @@ func isChrooted(t *testing.T) bool {
 
 func checkUserNS(t *testing.T) {
 	skipInContainer(t)
-	if _, err := os.Stat("/proc/self/ns/user"); err != nil {
-		if os.IsNotExist(err) {
-			t.Skip("kernel doesn't support user namespaces")
-		}
-		if os.IsPermission(err) {
-			t.Skip("unable to test user namespaces due to permissions")
-		}
-		t.Fatalf("Failed to stat /proc/self/ns/user: %v", err)
-	}
+	skipNoUserNamespaces(t)
 	if isChrooted(t) {
 		// create_user_ns in the kernel (see
 		// https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/kernel/user_namespace.c)
@@ -305,6 +317,7 @@ func TestGroupCleanupUserNamespace(t *testing.T) {
 		"uid=0(root) gid=0(root) groups=0(root),65534(nogroup)",
 		"uid=0(root) gid=0(root) groups=0(root),65534",
 		"uid=0(root) gid=0(root) groups=0(root),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody)", // Alpine; see https://golang.org/issue/19938
+		"uid=0(root) gid=0(root) groups=0(root) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023",                                                                               // CentOS with SELinux context, see https://golang.org/issue/34547
 	}
 	for _, e := range expected {
 		if strOut == e {
@@ -336,14 +349,6 @@ func TestUnshareMountNameSpace(t *testing.T) {
 		t.Skip("kernel prohibits unshare in unprivileged process, unless using user namespace")
 	}
 
-	// When running under the Go continuous build, skip tests for
-	// now when under Kubernetes. (where things are root but not quite)
-	// Both of these are our own environment variables.
-	// See Issue 12815.
-	if os.Getenv("GO_BUILDER_NAME") != "" && os.Getenv("IN_KUBERNETES") == "1" {
-		t.Skip("skipping test on Kubernetes-based builders; see Issue 12815")
-	}
-
 	d, err := ioutil.TempDir("", "unshare")
 	if err != nil {
 		t.Fatalf("tempdir: %v", err)
@@ -386,14 +391,6 @@ func TestUnshareMountNameSpaceChroot(t *testing.T) {
 		t.Skip("kernel prohibits unshare in unprivileged process, unless using user namespace")
 	}
 
-	// When running under the Go continuous build, skip tests for
-	// now when under Kubernetes. (where things are root but not quite)
-	// Both of these are our own environment variables.
-	// See Issue 12815.
-	if os.Getenv("GO_BUILDER_NAME") != "" && os.Getenv("IN_KUBERNETES") == "1" {
-		t.Skip("skipping test on Kubernetes-based builders; see Issue 12815")
-	}
-
 	d, err := ioutil.TempDir("", "unshare")
 	if err != nil {
 		t.Fatalf("tempdir: %v", err)
@@ -573,6 +570,7 @@ func TestAmbientCaps(t *testing.T) {
 }
 
 func TestAmbientCapsUserns(t *testing.T) {
+	checkUserNS(t)
 	testAmbientCaps(t, true)
 }
 
@@ -580,14 +578,6 @@ func testAmbientCaps(t *testing.T, userns bool) {
 	skipInContainer(t)
 	mustSupportAmbientCaps(t)
 
-	// When running under the Go continuous build, skip tests for
-	// now when under Kubernetes. (where things are root but not quite)
-	// Both of these are our own environment variables.
-	// See Issue 12815.
-	if os.Getenv("GO_BUILDER_NAME") != "" && os.Getenv("IN_KUBERNETES") == "1" {
-		t.Skip("skipping test on Kubernetes-based builders; see Issue 12815")
-	}
-
 	skipUnprivilegedUserClone(t)
 
 	// skip on android, due to lack of lookup support
diff --git a/libgo/go/syscall/fs_js.go b/libgo/go/syscall/fs_js.go
index 1b835c5..16d9f58 100644
--- a/libgo/go/syscall/fs_js.go
+++ b/libgo/go/syscall/fs_js.go
@@ -34,6 +34,7 @@ var (
 type jsFile struct {
 	path    string
 	entries []string
+	dirIdx  int // entries[:dirIdx] have already been returned in ReadDirent
 	pos     int64
 	seeked  bool
 }
@@ -141,8 +142,8 @@ func ReadDirent(fd int, buf []byte) (int, error) {
 	}
 
 	n := 0
-	for len(f.entries) > 0 {
-		entry := f.entries[0]
+	for f.dirIdx < len(f.entries) {
+		entry := f.entries[f.dirIdx]
 		l := 2 + len(entry)
 		if l > len(buf) {
 			break
@@ -152,7 +153,7 @@ func ReadDirent(fd int, buf []byte) (int, error) {
 		copy(buf[2:], entry)
 		buf = buf[l:]
 		n += l
-		f.entries = f.entries[1:]
+		f.dirIdx++
 	}
 
 	return n, nil
@@ -259,7 +260,7 @@ func Lchown(path string, uid, gid int) error {
 	if err := checkPath(path); err != nil {
 		return err
 	}
-	if jsFS.Get("lchown") == js.Undefined() {
+	if jsFS.Get("lchown").IsUndefined() {
 		// fs.lchown is unavailable on Linux until Node.js 10.6.0
 		// TODO(neelance): remove when we require at least this Node.js version
 		return ENOSYS
@@ -404,6 +405,14 @@ func Write(fd int, b []byte) (int, error) {
 		return n, err
 	}
 
+	if faketime && (fd == 1 || fd == 2) {
+		n := faketimeWrite(fd, b)
+		if n < 0 {
+			return 0, errnoErr(Errno(-n))
+		}
+		return n, nil
+	}
+
 	buf := uint8Array.New(len(b))
 	js.CopyBytesToJS(buf, b)
 	n, err := fsCall("write", fd, buf, 0, len(b), nil)
@@ -462,6 +471,7 @@ func Seek(fd int, offset int64, whence int) (int64, error) {
 	}
 
 	f.seeked = true
+	f.dirIdx = 0 // Reset directory read position. See issue 35767.
 	f.pos = newPos
 	return newPos, nil
 }
@@ -489,7 +499,7 @@ func fsCall(name string, args ...interface{}) (js.Value, error) {
 		var res callResult
 
 		if len(args) >= 1 { // on Node.js 8, fs.utimes calls the callback without any arguments
-			if jsErr := args[0]; jsErr != js.Null() {
+			if jsErr := args[0]; !jsErr.IsNull() {
 				res.err = mapJSError(jsErr)
 			}
 		}
diff --git a/libgo/go/syscall/getdirentries_test.go b/libgo/go/syscall/getdirentries_test.go
index 8505a0b..2a3419c 100644
--- a/libgo/go/syscall/getdirentries_test.go
+++ b/libgo/go/syscall/getdirentries_test.go
@@ -66,7 +66,11 @@ func testGetdirentries(t *testing.T, count int) {
 		}
 		data := buf[:n]
 		for len(data) > 0 {
-			dirent := (*syscall.Dirent)(unsafe.Pointer(&data[0]))
+			// If multiple Dirents are written into buf, sometimes when we reach the final one,
+			// we have cap(buf) < Sizeof(Dirent). So use an appropriate slice to copy from data.
+			var dirent syscall.Dirent
+			copy((*[unsafe.Sizeof(dirent)]byte)(unsafe.Pointer(&dirent))[:], data)
+
 			data = data[dirent.Reclen:]
 			name := make([]byte, dirent.Namlen)
 			for i := 0; i < int(dirent.Namlen); i++ {
diff --git a/libgo/go/syscall/js/export_test.go b/libgo/go/syscall/js/export_test.go
new file mode 100644
index 0000000..1b5ed3c
--- /dev/null
+++ b/libgo/go/syscall/js/export_test.go
@@ -0,0 +1,9 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build js,wasm
+
+package js
+
+var JSGo = jsGo
diff --git a/libgo/go/syscall/js/func.go b/libgo/go/syscall/js/func.go
index 6b7f39b..6c145c9 100644
--- a/libgo/go/syscall/js/func.go
+++ b/libgo/go/syscall/js/func.go
@@ -64,7 +64,7 @@ func init() {
 
 func handleEvent() {
 	cb := jsGo.Get("_pendingEvent")
-	if cb == Null() {
+	if cb.IsNull() {
 		return
 	}
 	jsGo.Set("_pendingEvent", Null())
diff --git a/libgo/go/syscall/js/js.go b/libgo/go/syscall/js/js.go
index 7300d2c..8a04399 100644
--- a/libgo/go/syscall/js/js.go
+++ b/libgo/go/syscall/js/js.go
@@ -12,6 +12,7 @@
 package js
 
 import (
+	"runtime"
 	"unsafe"
 )
 
@@ -20,7 +21,7 @@ import (
 // The JavaScript value "undefined" is represented by the value 0.
 // A JavaScript number (64-bit float, except 0 and NaN) is represented by its IEEE 754 binary representation.
 // All other values are represented as an IEEE 754 binary representation of NaN with bits 0-31 used as
-// an ID and bits 32-33 used to differentiate between string, symbol, function and object.
+// an ID and bits 32-34 used to differentiate between string, symbol, function and object.
 type ref uint64
 
 // nanHead are the upper 32 bits of a ref which are set if the value is not encoded as an IEEE 754 number (see above).
@@ -33,21 +34,45 @@ type Wrapper interface {
 }
 
 // Value represents a JavaScript value. The zero value is the JavaScript value "undefined".
+// Values can be checked for equality with the Equal method.
 type Value struct {
-	ref ref
+	_     [0]func() // uncomparable; to make == not compile
+	ref   ref       // identifies a JavaScript value, see ref type
+	gcPtr *ref      // used to trigger the finalizer when the Value is not referenced any more
 }
 
+const (
+	// the type flags need to be in sync with wasm_exec.js
+	typeFlagNone = iota
+	typeFlagObject
+	typeFlagString
+	typeFlagSymbol
+	typeFlagFunction
+)
+
 // JSValue implements Wrapper interface.
 func (v Value) JSValue() Value {
 	return v
 }
 
-func makeValue(v ref) Value {
-	return Value{ref: v}
+func makeValue(r ref) Value {
+	var gcPtr *ref
+	typeFlag := (r >> 32) & 7
+	if (r>>32)&nanHead == nanHead && typeFlag != typeFlagNone {
+		gcPtr = new(ref)
+		*gcPtr = r
+		runtime.SetFinalizer(gcPtr, func(p *ref) {
+			finalizeRef(*p)
+		})
+	}
+
+	return Value{ref: r, gcPtr: gcPtr}
 }
 
-func predefValue(id uint32) Value {
-	return Value{ref: nanHead<<32 | ref(id)}
+func finalizeRef(r ref)
+
+func predefValue(id uint32, typeFlag byte) Value {
+	return Value{ref: (nanHead|ref(typeFlag))<<32 | ref(id)}
 }
 
 func floatValue(f float64) Value {
@@ -73,28 +98,48 @@ func (e Error) Error() string {
 
 var (
 	valueUndefined = Value{ref: 0}
-	valueNaN       = predefValue(0)
-	valueZero      = predefValue(1)
-	valueNull      = predefValue(2)
-	valueTrue      = predefValue(3)
-	valueFalse     = predefValue(4)
-	valueGlobal    = predefValue(5)
-	jsGo           = predefValue(6) // instance of the Go class in JavaScript
+	valueNaN       = predefValue(0, typeFlagNone)
+	valueZero      = predefValue(1, typeFlagNone)
+	valueNull      = predefValue(2, typeFlagNone)
+	valueTrue      = predefValue(3, typeFlagNone)
+	valueFalse     = predefValue(4, typeFlagNone)
+	valueGlobal    = predefValue(5, typeFlagObject)
+	jsGo           = predefValue(6, typeFlagObject) // instance of the Go class in JavaScript
 
 	objectConstructor = valueGlobal.Get("Object")
 	arrayConstructor  = valueGlobal.Get("Array")
 )
 
+// Equal reports whether v and w are equal according to JavaScript's === operator.
+func (v Value) Equal(w Value) bool {
+	return v.ref == w.ref && v.ref != valueNaN.ref
+}
+
 // Undefined returns the JavaScript value "undefined".
 func Undefined() Value {
 	return valueUndefined
 }
 
+// IsUndefined reports whether v is the JavaScript value "undefined".
+func (v Value) IsUndefined() bool {
+	return v.ref == valueUndefined.ref
+}
+
 // Null returns the JavaScript value "null".
 func Null() Value {
 	return valueNull
 }
 
+// IsNull reports whether v is the JavaScript value "null".
+func (v Value) IsNull() bool {
+	return v.ref == valueNull.ref
+}
+
+// IsNaN reports whether v is the JavaScript value "NaN".
+func (v Value) IsNaN() bool {
+	return v.ref == valueNaN.ref
+}
+
 // Global returns the JavaScript global object, usually "window" or "global".
 func Global() Value {
 	return valueGlobal
@@ -232,16 +277,18 @@ func (v Value) Type() Type {
 	if v.isNumber() {
 		return TypeNumber
 	}
-	typeFlag := v.ref >> 32 & 3
+	typeFlag := (v.ref >> 32) & 7
 	switch typeFlag {
-	case 1:
+	case typeFlagObject:
+		return TypeObject
+	case typeFlagString:
 		return TypeString
-	case 2:
+	case typeFlagSymbol:
 		return TypeSymbol
-	case 3:
+	case typeFlagFunction:
 		return TypeFunction
 	default:
-		return TypeObject
+		panic("bad type flag")
 	}
 }
 
@@ -251,7 +298,9 @@ func (v Value) Get(p string) Value {
 	if vType := v.Type(); !vType.isObject() {
 		panic(&ValueError{"Value.Get", vType})
 	}
-	return makeValue(valueGet(v.ref, p))
+	r := makeValue(valueGet(v.ref, p))
+	runtime.KeepAlive(v)
+	return r
 }
 
 func valueGet(v ref, p string) ref
@@ -262,18 +311,35 @@ func (v Value) Set(p string, x interface{}) {
 	if vType := v.Type(); !vType.isObject() {
 		panic(&ValueError{"Value.Set", vType})
 	}
-	valueSet(v.ref, p, ValueOf(x).ref)
+	xv := ValueOf(x)
+	valueSet(v.ref, p, xv.ref)
+	runtime.KeepAlive(v)
+	runtime.KeepAlive(xv)
 }
 
 func valueSet(v ref, p string, x ref)
 
+// Delete deletes the JavaScript property p of value v.
+// It panics if v is not a JavaScript object.
+func (v Value) Delete(p string) {
+	if vType := v.Type(); !vType.isObject() {
+		panic(&ValueError{"Value.Delete", vType})
+	}
+	valueDelete(v.ref, p)
+	runtime.KeepAlive(v)
+}
+
+func valueDelete(v ref, p string)
+
 // Index returns JavaScript index i of value v.
 // It panics if v is not a JavaScript object.
 func (v Value) Index(i int) Value {
 	if vType := v.Type(); !vType.isObject() {
 		panic(&ValueError{"Value.Index", vType})
 	}
-	return makeValue(valueIndex(v.ref, i))
+	r := makeValue(valueIndex(v.ref, i))
+	runtime.KeepAlive(v)
+	return r
 }
 
 func valueIndex(v ref, i int) ref
@@ -284,17 +350,23 @@ func (v Value) SetIndex(i int, x interface{}) {
 	if vType := v.Type(); !vType.isObject() {
 		panic(&ValueError{"Value.SetIndex", vType})
 	}
-	valueSetIndex(v.ref, i, ValueOf(x).ref)
+	xv := ValueOf(x)
+	valueSetIndex(v.ref, i, xv.ref)
+	runtime.KeepAlive(v)
+	runtime.KeepAlive(xv)
 }
 
 func valueSetIndex(v ref, i int, x ref)
 
-func makeArgs(args []interface{}) []ref {
-	argVals := make([]ref, len(args))
+func makeArgs(args []interface{}) ([]Value, []ref) {
+	argVals := make([]Value, len(args))
+	argRefs := make([]ref, len(args))
 	for i, arg := range args {
-		argVals[i] = ValueOf(arg).ref
+		v := ValueOf(arg)
+		argVals[i] = v
+		argRefs[i] = v.ref
 	}
-	return argVals
+	return argVals, argRefs
 }
 
 // Length returns the JavaScript property "length" of v.
@@ -303,7 +375,9 @@ func (v Value) Length() int {
 	if vType := v.Type(); !vType.isObject() {
 		panic(&ValueError{"Value.SetIndex", vType})
 	}
-	return valueLength(v.ref)
+	r := valueLength(v.ref)
+	runtime.KeepAlive(v)
+	return r
 }
 
 func valueLength(v ref) int
@@ -312,7 +386,10 @@ func valueLength(v ref) int
 // It panics if v has no method m.
 // The arguments get mapped to JavaScript values according to the ValueOf function.
 func (v Value) Call(m string, args ...interface{}) Value {
-	res, ok := valueCall(v.ref, m, makeArgs(args))
+	argVals, argRefs := makeArgs(args)
+	res, ok := valueCall(v.ref, m, argRefs)
+	runtime.KeepAlive(v)
+	runtime.KeepAlive(argVals)
 	if !ok {
 		if vType := v.Type(); !vType.isObject() { // check here to avoid overhead in success case
 			panic(&ValueError{"Value.Call", vType})
@@ -331,7 +408,10 @@ func valueCall(v ref, m string, args []ref) (ref, bool)
 // It panics if v is not a JavaScript function.
 // The arguments get mapped to JavaScript values according to the ValueOf function.
 func (v Value) Invoke(args ...interface{}) Value {
-	res, ok := valueInvoke(v.ref, makeArgs(args))
+	argVals, argRefs := makeArgs(args)
+	res, ok := valueInvoke(v.ref, argRefs)
+	runtime.KeepAlive(v)
+	runtime.KeepAlive(argVals)
 	if !ok {
 		if vType := v.Type(); vType != TypeFunction { // check here to avoid overhead in success case
 			panic(&ValueError{"Value.Invoke", vType})
@@ -347,7 +427,10 @@ func valueInvoke(v ref, args []ref) (ref, bool)
 // It panics if v is not a JavaScript function.
 // The arguments get mapped to JavaScript values according to the ValueOf function.
 func (v Value) New(args ...interface{}) Value {
-	res, ok := valueNew(v.ref, makeArgs(args))
+	argVals, argRefs := makeArgs(args)
+	res, ok := valueNew(v.ref, argRefs)
+	runtime.KeepAlive(v)
+	runtime.KeepAlive(argVals)
 	if !ok {
 		if vType := v.Type(); vType != TypeFunction { // check here to avoid overhead in success case
 			panic(&ValueError{"Value.Invoke", vType})
@@ -362,7 +445,7 @@ func valueNew(v ref, args []ref) (ref, bool)
 func (v Value) isNumber() bool {
 	return v.ref == valueZero.ref ||
 		v.ref == valueNaN.ref ||
-		(v.ref != valueUndefined.ref && v.ref>>32&nanHead != nanHead)
+		(v.ref != valueUndefined.ref && (v.ref>>32)&nanHead != nanHead)
 }
 
 func (v Value) float(method string) float64 {
@@ -427,15 +510,15 @@ func (v Value) Truthy() bool {
 func (v Value) String() string {
 	switch v.Type() {
 	case TypeString:
-		return jsString(v.ref)
+		return jsString(v)
 	case TypeUndefined:
 		return "<undefined>"
 	case TypeNull:
 		return "<null>"
 	case TypeBoolean:
-		return "<boolean: " + jsString(v.ref) + ">"
+		return "<boolean: " + jsString(v) + ">"
 	case TypeNumber:
-		return "<number: " + jsString(v.ref) + ">"
+		return "<number: " + jsString(v) + ">"
 	case TypeSymbol:
 		return "<symbol>"
 	case TypeObject:
@@ -447,10 +530,12 @@ func (v Value) String() string {
 	}
 }
 
-func jsString(v ref) string {
-	str, length := valuePrepareString(v)
+func jsString(v Value) string {
+	str, length := valuePrepareString(v.ref)
+	runtime.KeepAlive(v)
 	b := make([]byte, length)
 	valueLoadString(str, b)
+	finalizeRef(str)
 	return string(b)
 }
 
@@ -460,7 +545,10 @@ func valueLoadString(v ref, b []byte)
 
 // InstanceOf reports whether v is an instance of type t according to JavaScript's instanceof operator.
 func (v Value) InstanceOf(t Value) bool {
-	return valueInstanceOf(v.ref, t.ref)
+	r := valueInstanceOf(v.ref, t.ref)
+	runtime.KeepAlive(v)
+	runtime.KeepAlive(t)
+	return r
 }
 
 func valueInstanceOf(v ref, t ref) bool
@@ -482,6 +570,7 @@ func (e *ValueError) Error() string {
 // CopyBytesToGo panics if src is not an Uint8Array.
 func CopyBytesToGo(dst []byte, src Value) int {
 	n, ok := copyBytesToGo(dst, src.ref)
+	runtime.KeepAlive(src)
 	if !ok {
 		panic("syscall/js: CopyBytesToGo: expected src to be an Uint8Array")
 	}
@@ -495,6 +584,7 @@ func copyBytesToGo(dst []byte, src ref) (int, bool)
 // CopyBytesToJS panics if dst is not an Uint8Array.
 func CopyBytesToJS(dst Value, src []byte) int {
 	n, ok := copyBytesToJS(dst.ref, src)
+	runtime.KeepAlive(dst)
 	if !ok {
 		panic("syscall/js: CopyBytesToJS: expected dst to be an Uint8Array")
 	}
diff --git a/libgo/go/syscall/js/js_test.go b/libgo/go/syscall/js/js_test.go
index 7a1e346..fea4c13 100644
--- a/libgo/go/syscall/js/js_test.go
+++ b/libgo/go/syscall/js/js_test.go
@@ -18,6 +18,7 @@ package js_test
 import (
 	"fmt"
 	"math"
+	"runtime"
 	"syscall/js"
 	"testing"
 )
@@ -53,7 +54,7 @@ func TestBool(t *testing.T) {
 	if got := dummys.Get("otherBool").Bool(); got != want {
 		t.Errorf("got %#v, want %#v", got, want)
 	}
-	if dummys.Get("someBool") != dummys.Get("someBool") {
+	if !dummys.Get("someBool").Equal(dummys.Get("someBool")) {
 		t.Errorf("same value not equal")
 	}
 }
@@ -68,7 +69,7 @@ func TestString(t *testing.T) {
 	if got := dummys.Get("otherString").String(); got != want {
 		t.Errorf("got %#v, want %#v", got, want)
 	}
-	if dummys.Get("someString") != dummys.Get("someString") {
+	if !dummys.Get("someString").Equal(dummys.Get("someString")) {
 		t.Errorf("same value not equal")
 	}
 
@@ -105,7 +106,7 @@ func TestInt(t *testing.T) {
 	if got := dummys.Get("otherInt").Int(); got != want {
 		t.Errorf("got %#v, want %#v", got, want)
 	}
-	if dummys.Get("someInt") != dummys.Get("someInt") {
+	if !dummys.Get("someInt").Equal(dummys.Get("someInt")) {
 		t.Errorf("same value not equal")
 	}
 	if got := dummys.Get("zero").Int(); got != 0 {
@@ -141,20 +142,20 @@ func TestFloat(t *testing.T) {
 	if got := dummys.Get("otherFloat").Float(); got != want {
 		t.Errorf("got %#v, want %#v", got, want)
 	}
-	if dummys.Get("someFloat") != dummys.Get("someFloat") {
+	if !dummys.Get("someFloat").Equal(dummys.Get("someFloat")) {
 		t.Errorf("same value not equal")
 	}
 }
 
 func TestObject(t *testing.T) {
-	if dummys.Get("someArray") != dummys.Get("someArray") {
+	if !dummys.Get("someArray").Equal(dummys.Get("someArray")) {
 		t.Errorf("same value not equal")
 	}
 
 	// An object and its prototype should not be equal.
 	proto := js.Global().Get("Object").Get("prototype")
 	o := js.Global().Call("eval", "new Object()")
-	if proto == o {
+	if proto.Equal(o) {
 		t.Errorf("object equals to its prototype")
 	}
 }
@@ -167,26 +168,66 @@ func TestFrozenObject(t *testing.T) {
 	}
 }
 
+func TestEqual(t *testing.T) {
+	if !dummys.Get("someFloat").Equal(dummys.Get("someFloat")) {
+		t.Errorf("same float is not equal")
+	}
+	if !dummys.Get("emptyObj").Equal(dummys.Get("emptyObj")) {
+		t.Errorf("same object is not equal")
+	}
+	if dummys.Get("someFloat").Equal(dummys.Get("someInt")) {
+		t.Errorf("different values are not unequal")
+	}
+}
+
 func TestNaN(t *testing.T) {
-	want := js.ValueOf(math.NaN())
-	got := dummys.Get("NaN")
-	if got != want {
-		t.Errorf("got %#v, want %#v", got, want)
+	if !dummys.Get("NaN").IsNaN() {
+		t.Errorf("JS NaN is not NaN")
+	}
+	if !js.ValueOf(math.NaN()).IsNaN() {
+		t.Errorf("Go NaN is not NaN")
+	}
+	if dummys.Get("NaN").Equal(dummys.Get("NaN")) {
+		t.Errorf("NaN is equal to NaN")
 	}
 }
 
 func TestUndefined(t *testing.T) {
-	dummys.Set("test", js.Undefined())
-	if dummys == js.Undefined() || dummys.Get("test") != js.Undefined() || dummys.Get("xyz") != js.Undefined() {
-		t.Errorf("js.Undefined expected")
+	if !js.Undefined().IsUndefined() {
+		t.Errorf("undefined is not undefined")
+	}
+	if !js.Undefined().Equal(js.Undefined()) {
+		t.Errorf("undefined is not equal to undefined")
+	}
+	if dummys.IsUndefined() {
+		t.Errorf("object is undefined")
+	}
+	if js.Undefined().IsNull() {
+		t.Errorf("undefined is null")
+	}
+	if dummys.Set("test", js.Undefined()); !dummys.Get("test").IsUndefined() {
+		t.Errorf("could not set undefined")
 	}
 }
 
 func TestNull(t *testing.T) {
-	dummys.Set("test1", nil)
-	dummys.Set("test2", js.Null())
-	if dummys == js.Null() || dummys.Get("test1") != js.Null() || dummys.Get("test2") != js.Null() {
-		t.Errorf("js.Null expected")
+	if !js.Null().IsNull() {
+		t.Errorf("null is not null")
+	}
+	if !js.Null().Equal(js.Null()) {
+		t.Errorf("null is not equal to null")
+	}
+	if dummys.IsNull() {
+		t.Errorf("object is null")
+	}
+	if js.Null().IsUndefined() {
+		t.Errorf("null is undefined")
+	}
+	if dummys.Set("test", js.Null()); !dummys.Get("test").IsNull() {
+		t.Errorf("could not set null")
+	}
+	if dummys.Set("test", nil); !dummys.Get("test").IsNull() {
+		t.Errorf("could not set nil")
 	}
 }
 
@@ -212,6 +253,18 @@ func TestSet(t *testing.T) {
 	})
 }
 
+func TestDelete(t *testing.T) {
+	dummys.Set("test", 42)
+	dummys.Delete("test")
+	if dummys.Call("hasOwnProperty", "test").Bool() {
+		t.Errorf("property still exists")
+	}
+
+	expectValueError(t, func() {
+		dummys.Get("zero").Delete("badField")
+	})
+}
+
 func TestIndex(t *testing.T) {
 	if got := dummys.Get("someArray").Index(1).Int(); got != 42 {
 		t.Errorf("got %#v, want %#v", got, 42)
@@ -328,7 +381,7 @@ func TestValueOf(t *testing.T) {
 
 func TestZeroValue(t *testing.T) {
 	var v js.Value
-	if v != js.Undefined() {
+	if !v.IsUndefined() {
 		t.Error("zero js.Value is not js.Undefined()")
 	}
 }
@@ -366,6 +419,25 @@ func TestInvokeFunction(t *testing.T) {
 	}
 }
 
+func TestInterleavedFunctions(t *testing.T) {
+	c1 := make(chan struct{})
+	c2 := make(chan struct{})
+
+	js.Global().Get("setTimeout").Invoke(js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		c1 <- struct{}{}
+		<-c2
+		return nil
+	}), 0)
+
+	<-c1
+	c2 <- struct{}{}
+	// this goroutine is running, but the callback of setTimeout did not return yet, invoke another function now
+	f := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		return nil
+	})
+	f.Invoke()
+}
+
 func ExampleFuncOf() {
 	var cb js.Func
 	cb = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
@@ -484,3 +556,38 @@ func TestCopyBytesToJS(t *testing.T) {
 		})
 	}
 }
+
+func TestGarbageCollection(t *testing.T) {
+	before := js.JSGo.Get("_values").Length()
+	for i := 0; i < 1000; i++ {
+		_ = js.Global().Get("Object").New().Call("toString").String()
+		runtime.GC()
+	}
+	after := js.JSGo.Get("_values").Length()
+	if after-before > 500 {
+		t.Errorf("garbage collection ineffective")
+	}
+}
+
+// BenchmarkDOM is a simple benchmark which emulates a webapp making DOM operations.
+// It creates a div, and sets its id. Then searches by that id and sets some data.
+// Finally it removes that div.
+func BenchmarkDOM(b *testing.B) {
+	document := js.Global().Get("document")
+	if document.IsUndefined() {
+		b.Skip("Not a browser environment. Skipping.")
+	}
+	const data = "someString"
+	for i := 0; i < b.N; i++ {
+		div := document.Call("createElement", "div")
+		div.Call("setAttribute", "id", "myDiv")
+		document.Get("body").Call("appendChild", div)
+		myDiv := document.Call("getElementById", "myDiv")
+		myDiv.Set("innerHTML", data)
+
+		if got, want := myDiv.Get("innerHTML").String(), data; got != want {
+			b.Errorf("got %s, want %s", got, want)
+		}
+		document.Get("body").Call("removeChild", div)
+	}
+}
diff --git a/libgo/go/syscall/lsf_linux.go b/libgo/go/syscall/lsf_linux.go
index 16b702a..f38de62 100644
--- a/libgo/go/syscall/lsf_linux.go
+++ b/libgo/go/syscall/lsf_linux.go
@@ -23,6 +23,8 @@ func LsfJump(code, k, jt, jf int) *SockFilter {
 // Deprecated: Use golang.org/x/net/bpf instead.
 func LsfSocket(ifindex, proto int) (int, error) {
 	var lsall SockaddrLinklayer
+	// This is missing SOCK_CLOEXEC, but adding the flag
+	// could break callers.
 	s, e := Socket(AF_PACKET, SOCK_RAW, proto)
 	if e != nil {
 		return 0, e
@@ -46,7 +48,7 @@ type iflags struct {
 
 // Deprecated: Use golang.org/x/net/bpf instead.
 func SetLsfPromisc(name string, m bool) error {
-	s, e := Socket(AF_INET, SOCK_DGRAM, 0)
+	s, e := cloexecSocket(AF_INET, SOCK_DGRAM, 0)
 	if e != nil {
 		return e
 	}
diff --git a/libgo/go/syscall/net_js.go b/libgo/go/syscall/net_js.go
index d5bf1f4..25f171b 100644
--- a/libgo/go/syscall/net_js.go
+++ b/libgo/go/syscall/net_js.go
@@ -42,7 +42,7 @@ const (
 const (
 	_ = iota
 	F_DUPFD_CLOEXEC
-	SYS_FCNTL = 500 // unsupported; same value as net_nacl.go
+	SYS_FCNTL = 500 // unsupported
 )
 
 type Sockaddr interface {
diff --git a/libgo/go/syscall/netlink_linux.go b/libgo/go/syscall/netlink_linux.go
index 1cda8c7..0937ff7 100644
--- a/libgo/go/syscall/netlink_linux.go
+++ b/libgo/go/syscall/netlink_linux.go
@@ -50,7 +50,7 @@ func newNetlinkRouteRequest(proto, seq, family int) []byte {
 // NetlinkRIB returns routing information base, as known as RIB, which
 // consists of network facility information, states and parameters.
 func NetlinkRIB(proto, family int) ([]byte, error) {
-	s, err := Socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE)
+	s, err := cloexecSocket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE)
 	if err != nil {
 		return nil, err
 	}
diff --git a/libgo/go/syscall/route_freebsd_64bit.go b/libgo/go/syscall/route_freebsd_64bit.go
index 728837e..e70ba3d 100644
--- a/libgo/go/syscall/route_freebsd_64bit.go
+++ b/libgo/go/syscall/route_freebsd_64bit.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.
 
-// +build freebsd,amd64
+// +build freebsd,amd64 freebsd,arm64
 
 package syscall
 
diff --git a/libgo/go/syscall/security_windows.go b/libgo/go/syscall/security_windows.go
index db80d98..3a75759 100644
--- a/libgo/go/syscall/security_windows.go
+++ b/libgo/go/syscall/security_windows.go
@@ -163,7 +163,7 @@ func (sid *SID) String() (string, error) {
 		return "", e
 	}
 	defer LocalFree((Handle)(unsafe.Pointer(s)))
-	return UTF16ToString((*[256]uint16)(unsafe.Pointer(s))[:]), nil
+	return utf16PtrToString(s, 256), nil
 }
 
 // Len returns the length, in bytes, of a valid security identifier sid.
diff --git a/libgo/go/syscall/sock_cloexec_linux.go b/libgo/go/syscall/sock_cloexec_linux.go
new file mode 100644
index 0000000..600cf25
--- /dev/null
+++ b/libgo/go/syscall/sock_cloexec_linux.go
@@ -0,0 +1,29 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package syscall
+
+// This is a stripped down version of sysSocket from net/sock_cloexec.go.
+func cloexecSocket(family, sotype, proto int) (int, error) {
+	s, err := Socket(family, sotype|SOCK_CLOEXEC, proto)
+	switch err {
+	case nil:
+		return s, nil
+	default:
+		return -1, err
+	case EINVAL:
+	}
+
+	ForkLock.RLock()
+	s, err = Socket(family, sotype, proto)
+	if err == nil {
+		CloseOnExec(s)
+	}
+	ForkLock.RUnlock()
+	if err != nil {
+		Close(s)
+		return -1, err
+	}
+	return s, nil
+}
diff --git a/libgo/go/syscall/sockcmsg_dragonfly.go b/libgo/go/syscall/sockcmsg_dragonfly.go
new file mode 100644
index 0000000..d217d9e
--- /dev/null
+++ b/libgo/go/syscall/sockcmsg_dragonfly.go
@@ -0,0 +1,16 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package syscall
+
+// Round the length of a raw sockaddr up to align it properly.
+func cmsgAlignOf(salen int) int {
+	salign := sizeofPtr
+	if sizeofPtr == 8 && !supportsABI(_dragonflyABIChangeVersion) {
+		// 64-bit Dragonfly before the September 2019 ABI changes still requires
+		// 32-bit aligned access to network subsystem.
+		salign = 4
+	}
+	return (salen + salign - 1) & ^(salign - 1)
+}
diff --git a/libgo/go/syscall/sockcmsg_linux.go b/libgo/go/syscall/sockcmsg_linux.go
index 4cb9075..d97667c 100644
--- a/libgo/go/syscall/sockcmsg_linux.go
+++ b/libgo/go/syscall/sockcmsg_linux.go
@@ -17,7 +17,7 @@ func UnixCredentials(ucred *Ucred) []byte {
 	h.Level = SOL_SOCKET
 	h.Type = SCM_CREDENTIALS
 	h.SetLen(CmsgLen(SizeofUcred))
-	*((*Ucred)(cmsgData(h))) = *ucred
+	*(*Ucred)(h.data(0)) = *ucred
 	return b
 }
 
diff --git a/libgo/go/syscall/sockcmsg_unix.go b/libgo/go/syscall/sockcmsg_unix.go
index dd74417..6530bea 100644
--- a/libgo/go/syscall/sockcmsg_unix.go
+++ b/libgo/go/syscall/sockcmsg_unix.go
@@ -9,35 +9,9 @@
 package syscall
 
 import (
-	"runtime"
 	"unsafe"
 )
 
-// Round the length of a raw sockaddr up to align it properly.
-func cmsgAlignOf(salen int) int {
-	salign := int(sizeofPtr)
-
-	switch runtime.GOOS {
-	case "aix":
-		// There is no alignment on AIX.
-		salign = 1
-	case "darwin", "dragonfly", "illumos", "solaris":
-		// NOTE: It seems like 64-bit Darwin, DragonFly BSD and
-		// Solaris kernels still require 32-bit aligned access to
-		// network subsystem.
-		if sizeofPtr == 8 {
-			salign = 4
-		}
-	case "netbsd", "openbsd":
-		// NetBSD and OpenBSD armv7 require 64-bit alignment.
-		if runtime.GOARCH == "arm" {
-			salign = 8
-		}
-	}
-
-	return (salen + salign - 1) & ^(salign - 1)
-}
-
 // CmsgLen returns the value to store in the Len field of the Cmsghdr
 // structure, taking into account any necessary alignment.
 func CmsgLen(datalen int) int {
@@ -50,8 +24,8 @@ func CmsgSpace(datalen int) int {
 	return cmsgAlignOf(SizeofCmsghdr) + cmsgAlignOf(datalen)
 }
 
-func cmsgData(h *Cmsghdr) unsafe.Pointer {
-	return unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(cmsgAlignOf(SizeofCmsghdr)))
+func (h *Cmsghdr) data(offset uintptr) unsafe.Pointer {
+	return unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(cmsgAlignOf(SizeofCmsghdr)) + offset)
 }
 
 // SocketControlMessage represents a socket control message.
@@ -94,10 +68,8 @@ func UnixRights(fds ...int) []byte {
 	h.Level = SOL_SOCKET
 	h.Type = SCM_RIGHTS
 	h.SetLen(CmsgLen(datalen))
-	data := cmsgData(h)
-	for _, fd := range fds {
-		*(*int32)(data) = int32(fd)
-		data = unsafe.Pointer(uintptr(data) + 4)
+	for i, fd := range fds {
+		*(*int32)(h.data(4 * uintptr(i))) = int32(fd)
 	}
 	return b
 }
diff --git a/libgo/go/syscall/sockcmsg_unix_other.go b/libgo/go/syscall/sockcmsg_unix_other.go
new file mode 100644
index 0000000..65d9f18
--- /dev/null
+++ b/libgo/go/syscall/sockcmsg_unix_other.go
@@ -0,0 +1,38 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build aix darwin freebsd linux netbsd openbsd solaris
+
+package syscall
+
+import (
+	"runtime"
+)
+
+// Round the length of a raw sockaddr up to align it properly.
+func cmsgAlignOf(salen int) int {
+	salign := int(sizeofPtr)
+
+	// dragonfly needs to check ABI version at runtime, see cmsgAlignOf in
+	// sockcmsg_dragonfly.go
+	switch runtime.GOOS {
+	case "aix":
+		// There is no alignment on AIX.
+		salign = 1
+	case "darwin", "illumos", "solaris":
+		// NOTE: It seems like 64-bit Darwin, Illumos and Solaris
+		// kernels still require 32-bit aligned access to network
+		// subsystem.
+		if sizeofPtr == 8 {
+			salign = 4
+		}
+	case "netbsd", "openbsd":
+		// NetBSD and OpenBSD armv7 require 64-bit alignment.
+		if runtime.GOARCH == "arm" {
+			salign = 8
+		}
+	}
+
+	return (salen + salign - 1) & ^(salign - 1)
+}
diff --git a/libgo/go/syscall/syscall.go b/libgo/go/syscall/syscall.go
index 9b74afe..4e1187b 100644
--- a/libgo/go/syscall/syscall.go
+++ b/libgo/go/syscall/syscall.go
@@ -28,7 +28,7 @@ package syscall
 
 import "unsafe"
 
-//go:generate go run mksyscall_windows.go -systemdll -output zsyscall_windows.go syscall_windows.go security_windows.go
+//go:generate go run golang.org/x/sys/windows/mkwinsyscall -systemdll -output zsyscall_windows.go syscall_windows.go security_windows.go
 
 // StringByteSlice converts a string to a NUL-terminated []byte,
 // If s contains a NUL byte this function panics instead of
diff --git a/libgo/go/syscall/syscall_aix.go b/libgo/go/syscall/syscall_aix.go
index 231ff40..f4cac01 100644
--- a/libgo/go/syscall/syscall_aix.go
+++ b/libgo/go/syscall/syscall_aix.go
@@ -23,5 +23,9 @@ func direntReclen(buf []byte) (uint64, bool) {
 }
 
 func direntNamlen(buf []byte) (uint64, bool) {
-	return readInt(buf, unsafe.Offsetof(Dirent{}.Namlen), unsafe.Sizeof(Dirent{}.Namlen))
+	reclen, ok := direntReclen(buf)
+	if !ok {
+		return 0, false
+	}
+	return reclen - uint64(unsafe.Offsetof(Dirent{}.Name)), true
 }
diff --git a/libgo/go/syscall/syscall_dragonfly.go b/libgo/go/syscall/syscall_dragonfly.go
index 3e6617c..930bb46 100644
--- a/libgo/go/syscall/syscall_dragonfly.go
+++ b/libgo/go/syscall/syscall_dragonfly.go
@@ -4,7 +4,25 @@
 
 package syscall
 
-import "unsafe"
+import (
+	"sync"
+	"unsafe"
+)
+
+// See version list in https://github.com/DragonFlyBSD/DragonFlyBSD/blob/master/sys/sys/param.h
+var (
+	osreldateOnce sync.Once
+	osreldate     uint32
+)
+
+// First __DragonFly_version after September 2019 ABI changes
+// http://lists.dragonflybsd.org/pipermail/users/2019-September/358280.html
+const _dragonflyABIChangeVersion = 500705
+
+func supportsABI(ver uint32) bool {
+	osreldateOnce.Do(func() { osreldate, _ = SysctlUint32("kern.osreldate") })
+	return osreldate >= ver
+}
 
 func direntIno(buf []byte) (uint64, bool) {
 	return readInt(buf, unsafe.Offsetof(Dirent{}.Fileno), unsafe.Sizeof(Dirent{}.Fileno))
diff --git a/libgo/go/syscall/syscall_errno.go b/libgo/go/syscall/syscall_errno.go
index a339ae8..0d781de 100644
--- a/libgo/go/syscall/syscall_errno.go
+++ b/libgo/go/syscall/syscall_errno.go
@@ -13,6 +13,12 @@ import "internal/oserror"
 //	if errno != 0 {
 //		err = errno
 //	}
+//
+// Errno values can be tested against error values from the os package
+// using errors.Is. For example:
+//
+//	_, _, err := syscall.Syscall(...)
+//	if errors.Is(err, os.ErrNotExist) ...
 type Errno uintptr
 
 func (e Errno) Error() string {
@@ -32,7 +38,7 @@ func (e Errno) Is(target error) bool {
 }
 
 func (e Errno) Temporary() bool {
-	return e == EINTR || e == EMFILE || e.Timeout()
+	return e == EINTR || e == EMFILE || e == ENFILE || e.Timeout()
 }
 
 func (e Errno) Timeout() bool {
diff --git a/libgo/go/syscall/syscall_freebsd_arm64.go b/libgo/go/syscall/syscall_freebsd_arm64.go
new file mode 100644
index 0000000..b561141
--- /dev/null
+++ b/libgo/go/syscall/syscall_freebsd_arm64.go
@@ -0,0 +1,33 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package syscall
+
+import "unsafe"
+
+func setTimespec(sec, nsec int64) Timespec {
+	return Timespec{Sec: sec, Nsec: nsec}
+}
+
+func setTimeval(sec, usec int64) Timeval {
+	return Timeval{Sec: sec, Usec: usec}
+}
+
+func SetKevent(k *Kevent_t, fd, mode, flags int) {
+	k.Ident = uint64(fd)
+	k.Filter = int16(mode)
+	k.Flags = uint16(flags)
+}
+
+func (iov *Iovec) SetLen(length int) {
+	iov.Len = uint64(length)
+}
+
+func (msghdr *Msghdr) SetControllen(length int) {
+	msghdr.Controllen = uint32(length)
+}
+
+func (cmsg *Cmsghdr) SetLen(length int) {
+	cmsg.Len = uint32(length)
+}
diff --git a/libgo/go/syscall/syscall_js.go b/libgo/go/syscall/syscall_js.go
index 175fe47..dfb4a27 100644
--- a/libgo/go/syscall/syscall_js.go
+++ b/libgo/go/syscall/syscall_js.go
@@ -44,6 +44,12 @@ const PathMax = 256
 //	if errno != 0 {
 //		err = errno
 //	}
+//
+// Errno values can be tested against error values from the os package
+// using errors.Is. For example:
+//
+//	_, _, err := syscall.Syscall(...)
+//	if errors.Is(err, os.ErrNotExist) ...
 type Errno uintptr
 
 func (e Errno) Error() string {
@@ -297,9 +303,10 @@ func Getegid() int {
 	return jsProcess.Call("getegid").Int()
 }
 
-func Getgroups() ([]int, error) {
+func Getgroups() (groups []int, err error) {
+	defer recoverErr(&err)
 	array := jsProcess.Call("getgroups")
-	groups := make([]int, array.Length())
+	groups = make([]int, array.Length())
 	for i := range groups {
 		groups[i] = array.Index(i).Int()
 	}
diff --git a/libgo/go/syscall/syscall_linux_riscv64.go b/libgo/go/syscall/syscall_linux_riscv64.go
new file mode 100644
index 0000000..e9aab94
--- /dev/null
+++ b/libgo/go/syscall/syscall_linux_riscv64.go
@@ -0,0 +1,23 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package syscall
+
+import "unsafe"
+
+func (r *PtraceRegs) PC() uint64 { return r.Pc }
+
+func (r *PtraceRegs) SetPC(pc uint64) { r.Pc = pc }
+
+func (iov *Iovec) SetLen(length int) {
+	iov.Len = uint64(length)
+}
+
+func (msghdr *Msghdr) SetControllen(length int) {
+	msghdr.Controllen = uint64(length)
+}
+
+func (cmsg *Cmsghdr) SetLen(length int) {
+	cmsg.Len = uint64(length)
+}
diff --git a/libgo/go/syscall/syscall_linux_test.go b/libgo/go/syscall/syscall_linux_test.go
index 2ad2365..97059c8 100644
--- a/libgo/go/syscall/syscall_linux_test.go
+++ b/libgo/go/syscall/syscall_linux_test.go
@@ -299,6 +299,14 @@ func TestSyscallNoError(t *testing.T) {
 		t.Skip("skipping on non-32bit architecture")
 	}
 
+	// See https://golang.org/issue/35422
+	// On MIPS, Linux returns whether the syscall had an error in a separate
+	// register (R7), not using a negative return value as on other
+	// architectures.
+	if runtime.GOARCH == "mips" || runtime.GOARCH == "mipsle" {
+		t.Skipf("skipping on %s", runtime.GOARCH)
+	}
+
 	if os.Getuid() != 0 {
 		t.Skip("skipping root only test")
 	}
@@ -367,7 +375,8 @@ func TestSyscallNoError(t *testing.T) {
 		if filesystemIsNoSUID(tmpBinary) {
 			t.Skip("skipping test when temp dir is mounted nosuid")
 		}
-		t.Errorf("expected %s, got %s", want, got)
+		// formatted so the values are aligned for easier comparison
+		t.Errorf("expected %s,\ngot      %s", want, got)
 	}
 }
 
diff --git a/libgo/go/syscall/syscall_test.go b/libgo/go/syscall/syscall_test.go
index 2a9d90e..5390f8a 100644
--- a/libgo/go/syscall/syscall_test.go
+++ b/libgo/go/syscall/syscall_test.go
@@ -62,7 +62,7 @@ func TestExecErrPermutedFds(t *testing.T) {
 }
 
 func TestGettimeofday(t *testing.T) {
-	if runtime.GOOS == "nacl" || runtime.GOOS == "js" {
+	if runtime.GOOS == "js" {
 		t.Skip("not implemented on " + runtime.GOOS)
 	}
 	tv := &syscall.Timeval{}
diff --git a/libgo/go/syscall/syscall_unix.go b/libgo/go/syscall/syscall_unix.go
index 37999a2..16e4d480 100644
--- a/libgo/go/syscall/syscall_unix.go
+++ b/libgo/go/syscall/syscall_unix.go
@@ -165,7 +165,14 @@ func Write(fd int, p []byte) (n int, err error) {
 	if race.Enabled {
 		race.ReleaseMerge(unsafe.Pointer(&ioSync))
 	}
-	n, err = write(fd, p)
+	if faketime && (fd == 1 || fd == 2) {
+		n = faketimeWrite(fd, p)
+		if n < 0 {
+			n, err = 0, errnoErr(Errno(-n))
+		}
+	} else {
+		n, err = write(fd, p)
+	}
 	if race.Enabled && n > 0 {
 		race.ReadRange(unsafe.Pointer(&p[0]), n)
 	}
diff --git a/libgo/go/syscall/syscall_unix_test.go b/libgo/go/syscall/syscall_unix_test.go
index da259b9..b99e07d 100644
--- a/libgo/go/syscall/syscall_unix_test.go
+++ b/libgo/go/syscall/syscall_unix_test.go
@@ -386,3 +386,9 @@ func TestSetsockoptString(t *testing.T) {
 		t.Fatalf("SetsockoptString: did not fail")
 	}
 }
+
+func TestENFILETemporary(t *testing.T) {
+	if !syscall.ENFILE.Temporary() {
+		t.Error("ENFILE is not treated as a temporary error")
+	}
+}
diff --git a/libgo/go/syscall/tables_nacljs.go b/libgo/go/syscall/tables_js.go
index 1c265f2..a7c4f8c 100644
--- a/libgo/go/syscall/tables_nacljs.go
+++ b/libgo/go/syscall/tables_js.go
@@ -2,13 +2,17 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build nacl js,wasm
+// +build js,wasm
 
 package syscall
 
 import "runtime"
 
-// TODO: generate with runtime/mknacl.sh, allow override with IRT.
+// These were originally used by Nacl, then later also used by
+// js/wasm. Now that they're only used by js/wasm, these numbers are
+// just arbitrary.
+//
+// TODO: delete? replace with something meaningful?
 const (
 	sys_null                 = 1
 	sys_nameservice          = 2
diff --git a/libgo/go/syscall/time_fake.go b/libgo/go/syscall/time_fake.go
new file mode 100644
index 0000000..5dec57a
--- /dev/null
+++ b/libgo/go/syscall/time_fake.go
@@ -0,0 +1,26 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build faketime
+
+package syscall
+
+import "unsafe"
+
+const faketime = true
+
+// When faketime is enabled, we redirect writes to FDs 1 and 2 through
+// the runtime's write function, since that adds the framing that
+// reports the emulated time.
+
+//go:linkname runtimeWrite runtime.write
+func runtimeWrite(fd uintptr, p unsafe.Pointer, n int32) int32
+
+func faketimeWrite(fd int, p []byte) int {
+	var pp *byte
+	if len(p) > 0 {
+		pp = &p[0]
+	}
+	return int(runtimeWrite(uintptr(fd), unsafe.Pointer(pp), int32(len(p))))
+}
diff --git a/libgo/go/syscall/time_nofake.go b/libgo/go/syscall/time_nofake.go
new file mode 100644
index 0000000..c94cef8
--- /dev/null
+++ b/libgo/go/syscall/time_nofake.go
@@ -0,0 +1,14 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !faketime
+
+package syscall
+
+const faketime = false
+
+func faketimeWrite(fd int, p []byte) int {
+	// This should never be called since faketime is false.
+	panic("not implemented")
+}
diff --git a/libgo/go/syscall/timestruct.go b/libgo/go/syscall/timestruct.go
index e2b7704..bd0b3de 100644
--- a/libgo/go/syscall/timestruct.go
+++ b/libgo/go/syscall/timestruct.go
@@ -2,13 +2,13 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build aix darwin dragonfly freebsd hurd js,wasm linux nacl netbsd openbsd solaris
+// +build aix darwin dragonfly freebsd hurd js,wasm linux netbsd openbsd solaris
 
 package syscall
 
 // TimespecToNsec converts a Timespec value into a number of
 // nanoseconds since the Unix epoch.
-func TimespecToNsec(ts Timespec) int64 { return int64(ts.Sec)*1e9 + int64(ts.Nsec) }
+func TimespecToNsec(ts Timespec) int64 { return ts.Nano() }
 
 // NsecToTimespec takes a number of nanoseconds since the Unix epoch
 // and returns the corresponding Timespec value.
@@ -24,7 +24,7 @@ func NsecToTimespec(nsec int64) Timespec {
 
 // TimevalToNsec converts a Timeval value into a number of nanoseconds
 // since the Unix epoch.
-func TimevalToNsec(tv Timeval) int64 { return int64(tv.Sec)*1e9 + int64(tv.Usec)*1e3 }
+func TimevalToNsec(tv Timeval) int64 { return tv.Nano() }
 
 // NsecToTimeval takes a number of nanoseconds since the Unix epoch
 // and returns the corresponding Timeval value.