Function UndoPrefixEnd

pkg/util/encoding/encoding.go:2442–2450

UndoPrefixEnd is a partial inverse for roachpb.Key.PrefixEnd. In general, we can't undo PrefixEnd because it is lossy; we don't know how many FFs were stripped from the original key. For example: - key: 01 02 03 FF FF - PrefixEnd: 01 02 04 - UndoPrefixEnd: 01 02 03 Some keys are n

(b []byte)

// UndoPrefixEnd is implemented here to avoid a circular dependency on roachpb,
// but arguably belongs in a byte-manipulation utility package.
func UndoPrefixEnd(b []byte) (_ []byte, ok bool) {
	if len(b) == 0 || b[len(b)-1] == 0 {
		// Not a possible result of PrefixEnd.
		return nil, false
	}
	out := append([]byte(nil), b...)
	out[len(out)-1]--
	return out, true
}

// MaxNonsortingVarintLen is the maximum length of an EncodeNonsortingVarint
// encoded value.