Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 81 insertions, 0 deletions

diff --git a/pkg/state/encode_unsafe.go b/pkg/state/encode_unsafe.go
new file mode 100644
index 000000000..d96ba56d4
--- /dev/null
+++ b/pkg/state/encode_unsafe.go
@@ -0,0 +1,81 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package state
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+// arrayFromSlice constructs a new pointer to the slice data.
+//
+// It would be similar to the following:
+//
+//	x := make([]Foo, l, c)
+//	a := ([l]Foo*)(unsafe.Pointer(x[0]))
+//
+func arrayFromSlice(obj reflect.Value) reflect.Value {
+	return reflect.NewAt(
+		reflect.ArrayOf(obj.Cap(), obj.Type().Elem()),
+		unsafe.Pointer(obj.Pointer()))
+}
+
+// pbSlice returns a protobuf-supported slice of the array and erase the
+// original element type (which could be a defined type or non-supported type).
+func pbSlice(obj reflect.Value) reflect.Value {
+	var typ reflect.Type
+	switch obj.Type().Elem().Kind() {
+	case reflect.Uint8:
+		typ = reflect.TypeOf(byte(0))
+	case reflect.Uint16:
+		typ = reflect.TypeOf(uint16(0))
+	case reflect.Uint32:
+		typ = reflect.TypeOf(uint32(0))
+	case reflect.Uint64:
+		typ = reflect.TypeOf(uint64(0))
+	case reflect.Uintptr:
+		typ = reflect.TypeOf(uint64(0))
+	case reflect.Int8:
+		typ = reflect.TypeOf(byte(0))
+	case reflect.Int16:
+		typ = reflect.TypeOf(int16(0))
+	case reflect.Int32:
+		typ = reflect.TypeOf(int32(0))
+	case reflect.Int64:
+		typ = reflect.TypeOf(int64(0))
+	case reflect.Bool:
+		typ = reflect.TypeOf(bool(false))
+	case reflect.Float32:
+		typ = reflect.TypeOf(float32(0))
+	case reflect.Float64:
+		typ = reflect.TypeOf(float64(0))
+	default:
+		panic("slice element is not of basic value type")
+	}
+	return reflect.NewAt(
+		reflect.ArrayOf(obj.Len(), typ),
+		unsafe.Pointer(obj.Slice(0, obj.Len()).Pointer()),
+	).Elem().Slice(0, obj.Len())
+}
+
+func castSlice(obj reflect.Value, elemTyp reflect.Type) reflect.Value {
+	if obj.Type().Elem().Size() != elemTyp.Size() {
+		panic("cannot cast slice into other element type of different size")
+	}
+	return reflect.NewAt(
+		reflect.ArrayOf(obj.Len(), elemTyp),
+		unsafe.Pointer(obj.Slice(0, obj.Len()).Pointer()),
+	).Elem()
+}