Sort map entries marshalling dag-cbor

ipld · Jul 16, 2021 · 20a0caf · 20a0caf
1 parent fc47eb2
commit 20a0caf
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Showing 3 changed files with 42 additions and 7 deletions.
diff --git a/codec/dagcbor/marshal.go b/codec/dagcbor/marshal.go
@@ -2,6 +2,7 @@ package dagcbor
 
 import (
 	"fmt"
+	"sort"
 
 	"github.com/polydawn/refmt/shared"
 	"github.com/polydawn/refmt/tok"
@@ -34,21 +35,39 @@ func marshal(n ipld.Node, tk *tok.Token, sink shared.TokenSink, allowLinks bool)
 		if _, err := sink.Step(tk); err != nil {
 			return err
 		}
-		// Emit map contents (and recurse).
+		// Collect map entries, then sort by key
+		type entry struct {
+			key   string
+			value ipld.Node
+		}
+		entries := []entry{}
 		for itr := n.MapIterator(); !itr.Done(); {
 			k, v, err := itr.Next()
 			if err != nil {
 				return err
 			}
-			tk.Type = tok.TString
-			tk.Str, err = k.AsString()
+			keyStr, err := k.AsString()
 			if err != nil {
 				return err
 			}
+			entries = append(entries, entry{keyStr, v})
+		}
+		// RFC7049 style sort as per DAG-CBOR spec
+		sort.Slice(entries, func(i, j int) bool {
+			li, lj := len(entries[i].key), len(entries[j].key)
+			if li == lj {
+				return entries[i].key < entries[j].key
+			}
+			return li < lj
+		})
+		// Emit map contents (and recurse).
+		for _, e := range entries {
+			tk.Type = tok.TString
+			tk.Str = e.key
 			if _, err := sink.Step(tk); err != nil {
 				return err
 			}
-			if err := marshal(v, tk, sink, allowLinks); err != nil {
+			if err := marshal(e.value, tk, sink, allowLinks); err != nil {
 				return err
 			}
 		}

diff --git a/codec/dagcbor/roundtripCidlink_test.go b/codec/dagcbor/roundtripCidlink_test.go
@@ -35,5 +35,5 @@ func TestRoundtripCidlink(t *testing.T) {
 
 	n2, err := lsys.Load(ipld.LinkContext{}, lnk, basicnode.Prototype.Any)
 	Require(t, err, ShouldEqual, nil)
-	Wish(t, n2, ShouldEqual, n)
+	Wish(t, n2, ShouldEqual, nSorted)
 }
diff --git a/codec/dagcbor/roundtrip_test.go b/codec/dagcbor/roundtrip_test.go
@@ -30,7 +30,23 @@ var n = fluent.MustBuildMap(basicnode.Prototype__Map{}, 4, func(na fluent.MapAss
 		})
 	})
 })
-var serial = "\xa4eplainkolde stringcmap\xa2cone\x01ctwo\x02dlist\x82ethreedfourfnested\xa1fdeeper\x81fthings"
+var nSorted = fluent.MustBuildMap(basicnode.Prototype__Map{}, 4, func(na fluent.MapAssembler) {
+	na.AssembleEntry("map").CreateMap(2, func(na fluent.MapAssembler) {
+		na.AssembleEntry("one").AssignInt(1)
+		na.AssembleEntry("two").AssignInt(2)
+	})
+	na.AssembleEntry("list").CreateList(2, func(na fluent.ListAssembler) {
+		na.AssembleValue().AssignString("three")
+		na.AssembleValue().AssignString("four")
+	})
+	na.AssembleEntry("plain").AssignString("olde string")
+	na.AssembleEntry("nested").CreateMap(1, func(na fluent.MapAssembler) {
+		na.AssembleEntry("deeper").CreateList(1, func(na fluent.ListAssembler) {
+			na.AssembleValue().AssignString("things")
+		})
+	})
+})
+var serial = "\xa4cmap\xa2cone\x01ctwo\x02dlist\x82ethreedfoureplainkolde stringfnested\xa1fdeeper\x81fthings"
 
 func TestRoundtrip(t *testing.T) {
 	t.Run("encoding", func(t *testing.T) {
@@ -44,7 +60,7 @@ func TestRoundtrip(t *testing.T) {
 		nb := basicnode.Prototype__Map{}.NewBuilder()
 		err := Decode(nb, buf)
 		Require(t, err, ShouldEqual, nil)
-		Wish(t, nb.Build(), ShouldEqual, n)
+		Wish(t, nb.Build(), ShouldEqual, nSorted)
 	})
 }