From 76353188a8a6f8b9093845ac6766573189b18a08 Mon Sep 17 00:00:00 2001
From: Will Scott <will.scott@protocol.ai>
Date: Wed, 13 Oct 2021 14:56:10 -0700
Subject: [PATCH 1/2] Add a cidlink.Memory storage option

---
 linking/cid/memorystorage.go | 51 ++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 linking/cid/memorystorage.go

diff --git a/linking/cid/memorystorage.go b/linking/cid/memorystorage.go
new file mode 100644
index 00000000..6666de03
--- /dev/null
+++ b/linking/cid/memorystorage.go
@@ -0,0 +1,51 @@
+package cidlink
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"github.com/ipld/go-ipld-prime/linking"
+)
+
+// Memory is a simple in-memory storage for cidlinks. It's the same as `storage.Memory`
+// but uses typical multihash semantics used when reading/writing cidlinks.
+type Memory struct {
+	Bag map[string][]byte
+}
+
+func (store *Memory) beInitialized() {
+	if store.Bag != nil {
+		return
+	}
+	store.Bag = make(map[string][]byte)
+}
+
+func (store *Memory) OpenRead(lnkCtx linking.LinkContext, lnk datamodel.Link) (io.Reader, error) {
+	store.beInitialized()
+	cl, ok := lnk.(Link)
+	if !ok {
+		return nil, fmt.Errorf("incompatible link type: %T", lnk)
+	}
+	data, exists := store.Bag[string(cl.Hash())]
+	if !exists {
+		return nil, os.ErrNotExist
+	}
+	return bytes.NewReader(data), nil
+}
+
+func (store *Memory) OpenWrite(lnkCtx linking.LinkContext) (io.Writer, linking.BlockWriteCommitter, error) {
+	store.beInitialized()
+	buf := bytes.Buffer{}
+	return &buf, func(lnk datamodel.Link) error {
+		cl, ok := lnk.(Link)
+		if !ok {
+			return fmt.Errorf("incompatible link type: %T", lnk)
+		}
+
+		store.Bag[string(cl.Hash())] = buf.Bytes()
+		return nil
+	}, nil
+}

From 4aa49264dced3bbe842960fa29bfe6cc678e32b8 Mon Sep 17 00:00:00 2001
From: Will <will.scott@protocol.ai>
Date: Wed, 13 Oct 2021 17:59:34 -0700
Subject: [PATCH 2/2] Update linking/cid/memorystorage.go

Co-authored-by: Rod Vagg <rod@vagg.org>
---
 linking/cid/memorystorage.go | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/linking/cid/memorystorage.go b/linking/cid/memorystorage.go
index 6666de03..cf1e3849 100644
--- a/linking/cid/memorystorage.go
+++ b/linking/cid/memorystorage.go
@@ -12,6 +12,11 @@ import (
 
 // Memory is a simple in-memory storage for cidlinks. It's the same as `storage.Memory`
 // but uses typical multihash semantics used when reading/writing cidlinks.
+//
+// Using multihash as the storage key rather than the whole CID will remove the
+// distinction between CIDv0 and their CIDv1 counterpart. It also removes the
+// distinction between CIDs where the multihash is the same but the codec is
+// different, e.g. `dag-cbor` and a `raw` version of the same data.
 type Memory struct {
 	Bag map[string][]byte
 }