From 6b19ca8b0ba9c694c7ce74e96a8a9f3e41fe8156 Mon Sep 17 00:00:00 2001
From: Petar Maymounkov <petarm@gmail.com>
Date: Thu, 26 May 2022 12:05:56 -0700
Subject: [PATCH 1/4] add option to not parse beyond end of structure

---
 codec/dagjson/unmarshal.go | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/codec/dagjson/unmarshal.go b/codec/dagjson/unmarshal.go
index 637aa3a7..6bc05b83 100644
--- a/codec/dagjson/unmarshal.go
+++ b/codec/dagjson/unmarshal.go
@@ -32,6 +32,10 @@ type DecodeOptions struct {
 	// If true, parse DAG-JSON `{"/":{"bytes":"base64 bytes..."}}` as a Bytes kind
 	// node rather than nested plain maps
 	ParseBytes bool
+
+	// If true, the decoder stops reading from the stream at the end of the JSON structure.
+	// I.e. it does not slurp remaining whitespaces and EOF.
+	DontParseBeyondEnd bool
 }
 
 // Decode deserializes data from the given io.Reader and feeds it into the given datamodel.NodeAssembler.
@@ -43,6 +47,9 @@ func (cfg DecodeOptions) Decode(na datamodel.NodeAssembler, r io.Reader) error {
 	if err != nil {
 		return err
 	}
+	if cfg.DontParseBeyondEnd {
+		return nil
+	}
 	// Slurp any remaining whitespace.
 	//  This behavior may be due for review.
 	//  (This is relevant if our reader is tee'ing bytes to a hasher, and

From d7f1bd2f6330d1fe218d7863a75ac83f20dbc352 Mon Sep 17 00:00:00 2001
From: Petar Maymounkov <petarm@gmail.com>
Date: Tue, 7 Jun 2022 08:23:02 -0700
Subject: [PATCH 2/4] add test

---
 codec/dagjson/nongreedy_test.go | 36 +++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 codec/dagjson/nongreedy_test.go

diff --git a/codec/dagjson/nongreedy_test.go b/codec/dagjson/nongreedy_test.go
new file mode 100644
index 00000000..892bcd5d
--- /dev/null
+++ b/codec/dagjson/nongreedy_test.go
@@ -0,0 +1,36 @@
+package dagjson
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"github.com/ipld/go-ipld-prime/node/basicnode"
+)
+
+func TestNonGreedy(t *testing.T) {
+	buf := bytes.NewBufferString(`{"a": 1}{"b": 2}`)
+	opts := DecodeOptions{
+		ParseLinks:         false,
+		ParseBytes:         false,
+		DontParseBeyondEnd: true,
+	}
+	nb1 := basicnode.Prototype.Map.NewBuilder()
+	err := opts.Decode(nb1, buf)
+	if err != nil {
+		t.Fatalf("first decode (%v)", err)
+	}
+	n1 := nb1.Build()
+	if n1.Kind() != datamodel.Kind_Map {
+		t.Errorf("expecting a map")
+	}
+	nb2 := basicnode.Prototype.Map.NewBuilder()
+	err = opts.Decode(nb2, buf)
+	if err != nil {
+		t.Fatalf("second decode (%v)", err)
+	}
+	n2 := nb2.Build()
+	if n2.Kind() != datamodel.Kind_Map {
+		t.Errorf("expecting a map")
+	}
+}

From 9ec03893a1f106cd3d02d4a7f08503f96ca7186e Mon Sep 17 00:00:00 2001
From: Petar Maymounkov <petarm@gmail.com>
Date: Tue, 7 Jun 2022 08:25:36 -0700
Subject: [PATCH 3/4] comment

---
 codec/dagjson/unmarshal.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/codec/dagjson/unmarshal.go b/codec/dagjson/unmarshal.go
index 6bc05b83..b51f4dac 100644
--- a/codec/dagjson/unmarshal.go
+++ b/codec/dagjson/unmarshal.go
@@ -34,7 +34,10 @@ type DecodeOptions struct {
 	ParseBytes bool
 
 	// If true, the decoder stops reading from the stream at the end of the JSON structure.
-	// I.e. it does not slurp remaining whitespaces and EOF.
+	// i.e. it does not slurp remaining whitespaces and EOF.
+	// As per standard IPLD behavior, the parser considers the entire block to be
+	// part of the JSON structure and will error if there is extraneous
+	// non-whitespace data.
 	DontParseBeyondEnd bool
 }
 

From f0c1fdf6c6adf23988529c143019f71242eafd0e Mon Sep 17 00:00:00 2001
From: Petar Maymounkov <petarm@gmail.com>
Date: Tue, 7 Jun 2022 09:01:21 -0700
Subject: [PATCH 4/4] add to test

---
 codec/dagjson/nongreedy_test.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/codec/dagjson/nongreedy_test.go b/codec/dagjson/nongreedy_test.go
index 892bcd5d..b6b03a4f 100644
--- a/codec/dagjson/nongreedy_test.go
+++ b/codec/dagjson/nongreedy_test.go
@@ -24,6 +24,9 @@ func TestNonGreedy(t *testing.T) {
 	if n1.Kind() != datamodel.Kind_Map {
 		t.Errorf("expecting a map")
 	}
+	if _, err := n1.LookupByString("a"); err != nil {
+		t.Fatalf("missing fist key")
+	}
 	nb2 := basicnode.Prototype.Map.NewBuilder()
 	err = opts.Decode(nb2, buf)
 	if err != nil {
@@ -33,4 +36,7 @@ func TestNonGreedy(t *testing.T) {
 	if n2.Kind() != datamodel.Kind_Map {
 		t.Errorf("expecting a map")
 	}
+	if _, err := n2.LookupByString("b"); err != nil {
+		t.Fatalf("missing second key")
+	}
 }