From 99c91d9bebf6de909a7d4c51838548fc5a7a7b19 Mon Sep 17 00:00:00 2001
From: Rod Vagg <rod@vagg.org>
Date: Wed, 25 May 2022 12:59:15 +1000
Subject: [PATCH] fixup! fix(codecs): coerce cid.Undef to null in
 dag{json,cbor} output

---
 codec/dagcbor/marshal.go      |  8 ++------
 codec/dagcbor/marshal_test.go | 18 ++----------------
 codec/dagjson/marshal.go      |  8 ++------
 codec/dagjson/marshal_test.go |  5 ++---
 4 files changed, 8 insertions(+), 31 deletions(-)

diff --git a/codec/dagcbor/marshal.go b/codec/dagcbor/marshal.go
index 328d6dcb..608f8a3e 100644
--- a/codec/dagcbor/marshal.go
+++ b/codec/dagcbor/marshal.go
@@ -5,7 +5,6 @@ import (
 	"io"
 	"sort"
 
-	"github.com/ipfs/go-cid"
 	"github.com/polydawn/refmt/cbor"
 	"github.com/polydawn/refmt/shared"
 	"github.com/polydawn/refmt/tok"
@@ -145,11 +144,8 @@ func marshal(n datamodel.Node, tk *tok.Token, sink shared.TokenSink, options Enc
 		}
 		switch lnk := v.(type) {
 		case cidlink.Link:
-			if lnk.Cid == cid.Undef {
-				// Undef is akin to null, so coerce it rather than produce an invalid output
-				tk.Type = tok.TNull
-				_, err := sink.Step(tk)
-				return err
+			if !lnk.Cid.Defined() {
+				return fmt.Errorf("encoding undefined CIDs are not supported by this codec")
 			}
 			tk.Type = tok.TBytes
 			tk.Bytes = append([]byte{0}, lnk.Bytes()...)
diff --git a/codec/dagcbor/marshal_test.go b/codec/dagcbor/marshal_test.go
index 53341948..7fc87f6b 100644
--- a/codec/dagcbor/marshal_test.go
+++ b/codec/dagcbor/marshal_test.go
@@ -2,7 +2,6 @@ package dagcbor
 
 import (
 	"bytes"
-	"encoding/hex"
 	"math/rand"
 	"testing"
 	"time"
@@ -82,19 +81,6 @@ func TestMarshalUndefCid(t *testing.T) {
 		qp.MapEntry(ma, "DefCid", qp.Link(cidlink.Link{Cid: link}))
 	})
 	qt.Assert(t, err, qt.IsNil)
-	byts, err := ipld.Encode(node, Encode)
-	qt.Assert(t, err, qt.IsNil)
-	/* this is what we're expecting:
-	a2                                                # map(2)
-	  66                                              #   string(6)
-	    446566436964                                  #     "DefCid"
-	  d8 2a                                           #   tag(42)
-	    58 25                                         #     bytes(37)
-	      0001701220c3c4733ec8affd06cf9e9ff50ffc6bcd  #       "\x00\x01p\x12 ÃÄs>ȯý\x06Ï\x9e\x9fõ\x0fükÍ"
-	      2ec85a6170004bb709669c31de94391a            #       ".ÈZap\x00K·\x09f\x9c1Þ\x949\x1a"
-	  68                                              #   string(8)
-	    556e646566436964                              #     "UndefCid"
-	  f6                                              #   null
-	*/
-	qt.Assert(t, hex.EncodeToString(byts), qt.Equals, "a266446566436964d82a58250001701220c3c4733ec8affd06cf9e9ff50ffc6bcd2ec85a6170004bb709669c31de94391a68556e646566436964f6")
+	_, err = ipld.Encode(node, Encode)
+	qt.Assert(t, err, qt.ErrorMatches, "encoding undefined CIDs are not supported by this codec")
 }
diff --git a/codec/dagjson/marshal.go b/codec/dagjson/marshal.go
index 467ac46d..8e1bba2a 100644
--- a/codec/dagjson/marshal.go
+++ b/codec/dagjson/marshal.go
@@ -6,7 +6,6 @@ import (
 	"io"
 	"sort"
 
-	"github.com/ipfs/go-cid"
 	"github.com/polydawn/refmt/json"
 	"github.com/polydawn/refmt/shared"
 	"github.com/polydawn/refmt/tok"
@@ -258,11 +257,8 @@ func Marshal(n datamodel.Node, sink shared.TokenSink, options EncodeOptions) err
 		}
 		switch lnk := v.(type) {
 		case cidlink.Link:
-			if lnk.Cid == cid.Undef {
-				// Undef is akin to null, so coerce it rather than produce an invalid output
-				tk.Type = tok.TNull
-				_, err := sink.Step(&tk)
-				return err
+			if !lnk.Cid.Defined() {
+				return fmt.Errorf("encoding undefined CIDs are not supported by this codec")
 			}
 			// Precisely four tokens to emit:
 			tk.Type = tok.TMapOpen
diff --git a/codec/dagjson/marshal_test.go b/codec/dagjson/marshal_test.go
index 17f0e691..542d2986 100644
--- a/codec/dagjson/marshal_test.go
+++ b/codec/dagjson/marshal_test.go
@@ -20,7 +20,6 @@ func TestMarshalUndefCid(t *testing.T) {
 		qp.MapEntry(ma, "DefCid", qp.Link(cidlink.Link{Cid: link}))
 	})
 	qt.Assert(t, err, qt.IsNil)
-	byts, err := ipld.Encode(node, Encode)
-	qt.Assert(t, err, qt.IsNil)
-	qt.Assert(t, string(byts), qt.Equals, `{"DefCid":{"/":"bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi"},"UndefCid":null}`)
+	_, err = ipld.Encode(node, Encode)
+	qt.Assert(t, err, qt.ErrorMatches, "encoding undefined CIDs are not supported by this codec")
 }