1 // Copyright 2023 The gVisor Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 15 //go:build go1.20
16 17 package gohacks
18 19 import (
20 "unsafe"
21 )
22 23 // ImmutableBytesFromString is equivalent to []byte(s), except that it uses the
24 // same memory backing s instead of making a heap-allocated copy. This is only
25 // valid if the returned slice is never mutated.
26 func ImmutableBytesFromString(s string) []byte {
27 b := unsafe.StringData(s)
28 return unsafe.Slice(b, len(s))
29 }
30 31 // StringFromImmutableBytes is equivalent to string(bs), except that it uses
32 // the same memory backing bs instead of making a heap-allocated copy. This is
33 // only valid if bs is never mutated after StringFromImmutableBytes returns.
34 func StringFromImmutableBytes(bs []byte) string {
35 if len(bs) == 0 {
36 return ""
37 }
38 return unsafe.String(&bs[0], len(bs))
39 }
40