On Tue, Apr 21, 2020 at 6:49 AM T L <tapir....@gmail.com> 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
> }
Since you are correctly using *reflect.StringHeader, it doesn't matter
whether the stack is copied at that moment. You are pointing at the
actual string value, so the pointer will be adjusted. As far as I can
see, this is safe. (Of course, it's not safe if somebody modifies the
contents of the returned []byte.)
Ian
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