And is the runtime.KeepAlive call in the following program essential to
keep the correctness?
package main
import (
"fmt"
"unsafe"
"reflect"
"runtime"
)
func main() {
a := [6]byte{'G', 'o', 'o', 'g', 'l', 'e'}
bs := []byte("Golang")
hdr := (*reflect.SliceHeader)(unsafe.Pointer(&bs))
hdr.Data = uintptr(unsafe.Pointer(&a))
runtime.KeepAlive(&a) // Is this line essential here?
hdr.Len = 2
hdr.Cap = len(a)
fmt.Printf("%s\n", bs) // Go
bs = bs[:cap(bs)]
fmt.Printf("%s\n", bs) // Google
}
On Tuesday, April 21, 2020 at 9:48:08 AM UTC-4, T L wrote:
>
> func String2ByteSlice(str string) (bs []byte) {
> strHdr := (*reflect.StringHeader)(unsafe.Pointer(&str))
> sliceHdr := (*reflect.SliceHeader)(unsafe.Pointer(&bs))
>
> // Is it possible that the str value is allocated on stack
> // and the stack grows at this moment, so the address value
> // stored in strHdr.Data will become obsoleted?
>
> sliceHdr.Data = strHdr.Data
> sliceHdr.Len = strHdr.Len
> sliceHdr.Cap = strHdr.Len
>
> runtime.KeepAlive(&str)
>
> return
> }
>
>
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