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