better checks at boundaries

Author: phbnf

cmd/proofgen/main.go

@@ -19,6 +19,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"math"
 	"math/bits"
 	"os"
 	"path/filepath"
@@ -340,16 +341,16 @@ func toSubtreeInclusionProbe(p inclusionProbe) subtreeInclusionProbe {
 func shiftSubtreeInclusionProbe(p subtreeInclusionProbe) subtreeInclusionProbe {
 	shift := bitCeil(p.End - p.Start)
 	desc := p.Desc + " - subtree"
-	leafIdx := p.LeafIdx
-	if leafIdx <= ^uint64(0)-shift {
+	leafIdx, start, end := p.LeafIdx, p.Start, p.End
+	if p.Start <= math.MaxUint64-shift && p.LeafIdx <= math.MaxUint64-shift && p.End <= math.MaxUint64-shift {
 		leafIdx += shift
-	} else {
-		leafIdx = ^uint64(0)
+		start += shift
+		end += shift
 	}
 	return subtreeInclusionProbe{
 		LeafIdx:   leafIdx,
-		Start:     p.Start + shift,
-		End:       p.End + shift,
+		Start:     start,
+		End:       end,
 		Root:      p.Root,
 		LeafHash:  p.LeafHash,
 		Proof:     p.Proof,

testdata/subtreeinclusion/0/leafIdx-sub-@1-subtree.json

@@ -1,7 +1,7 @@
 {
   "leafIdx": 18446744073709551615,
-  "start": 1,
-  "end": 2,
+  "start": 0,
+  "end": 1,
   "root": "bjQLnP+zepicpUTmu3gKLHiQHT+zNzh2hRGjBhevoB0=",
   "leafHash": "bjQLnP+zepicpUTmu3gKLHiQHT+zNzh2hRGjBhevoB0=",
   "proof": null,

testdata/subtreeinclusion/1/leafIdx-sub-@1-subtree.json

@@ -1,7 +1,7 @@
 {
   "leafIdx": 18446744073709551615,
-  "start": 8,
-  "end": 16,
+  "start": 0,
+  "end": 8,
   "root": "XcnaeacGWamtVZy3Ad7ZoqudgjqtL0lgz+Nw7/RgQyg=",
   "leafHash": "bjQLnP+zepicpUTmu3gKLHiQHT+zNzh2hRGjBhevoB0=",
   "proof": [