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// Copyright 2018 The gVisor Authors.
//
// 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()
}
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