Fix hash mismatch error on matching link pointer

datamodel/link.go

@@ -40,7 +40,7 @@ type Link interface {
 	// the golang string type is used for immutability and for ease of use as a map key.
 	// As with the String method, the returned value may not elide any parts of the hash.
 	//
-	// Note that there is still no contract that the returned value be able to be parsed back into a Link value;
+	// Note that there is still no contract that the returned value should be parsable back into a Link value;
 	// not even in the case of `lnk.Prototype().BuildLink(lnk.Binary()[:])`.
 	// This is because the value returned by this method may contain data that the LinkPrototype would also restate.
 	// (For a concrete example: if using CIDs, this method will return a binary string that includes

linking/functions.go

@@ -11,7 +11,7 @@ import (
 // This file contains all the functions on LinkSystem.
 // These are the helpful, user-facing functions we expect folks to use "most of the time" when loading and storing data.
 
-// Varations:
+// Variations:
 // - Load vs Store vs ComputeLink
 // - Load vs LoadPlusRaw
 // - With or without LinkContext?
@@ -141,7 +141,7 @@ func (lsys *LinkSystem) LoadRaw(lnkCtx LinkContext, lnk datamodel.Link) ([]byte,
 	hasher.Write(buf.Bytes())
 	hash := hasher.Sum(nil)
 	lnk2 := lnk.Prototype().BuildLink(hash)
-	if lnk2 != lnk {
+	if lnk2.Binary() != lnk.Binary() {
 		return nil, ErrHashMismatch{Actual: lnk2, Expected: lnk}
 	}
 	// No codec to deploy; this is the raw load function.
@@ -205,7 +205,7 @@ func (lsys *LinkSystem) Fill(lnkCtx LinkContext, lnk datamodel.Link, na datamode
 	// (Then do a bit of a jig to build a link out of it -- because that's what we do the actual hash equality check on.)
 	hash := hasher.Sum(nil)
 	lnk2 := lnk.Prototype().BuildLink(hash)
-	if lnk2 != lnk {
+	if lnk2.Binary() != lnk.Binary() {
 		return ErrHashMismatch{Actual: lnk2, Expected: lnk}
 	}
 	// If we got all the way through IO and through the hash check:

linking/functions_test.go

@@ -0,0 +1,73 @@
+package linking_test
+
+import (
+	"bytes"
+	"context"
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+	"github.com/ipfs/go-cid"
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/codec/dagcbor"
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"github.com/ipld/go-ipld-prime/fluent"
+	cidlink "github.com/ipld/go-ipld-prime/linking/cid"
+	"github.com/ipld/go-ipld-prime/node/basicnode"
+	"github.com/ipld/go-ipld-prime/storage/memstore"
+	"github.com/multiformats/go-multicodec"
+)
+
+func TestLinkSystem_LoadHashMismatch(t *testing.T) {
+	subject := cidlink.DefaultLinkSystem()
+	storage := &memstore.Store{}
+	subject.SetReadStorage(storage)
+	subject.SetWriteStorage(storage)
+
+	// Construct some test IPLD node.
+	wantNode := fluent.MustBuildMap(basicnode.Prototype.Map, 1, func(na fluent.MapAssembler) {
+		na.AssembleEntry("fish").AssignString("barreleye")
+	})
+
+	// Encode as raw value to be used for testing LoadRaw
+	var buf bytes.Buffer
+	qt.Check(t, dagcbor.Encode(wantNode, &buf), qt.IsNil)
+	wantNodeRaw := buf.Bytes()
+
+	// Store the test IPLD node and get link back.
+	lctx := ipld.LinkContext{Ctx: context.TODO()}
+	gotLink, err := subject.Store(lctx, cidlink.LinkPrototype{
+		Prefix: cid.Prefix{
+			Version:  1,
+			Codec:    uint64(multicodec.DagCbor),
+			MhType:   uint64(multicodec.Sha2_256),
+			MhLength: -1,
+		},
+	}, wantNode)
+	qt.Check(t, err, qt.IsNil)
+	gotCidlink := gotLink.(cidlink.Link)
+
+	// Assert all load variations return expected values for different link representations.
+	for _, test := range []struct {
+		name string
+		link datamodel.Link
+	}{
+		{"datamodel.Link", gotLink},
+		{"cidlink.Link", gotCidlink},
+		{"&cidlink.Link", &gotCidlink},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			gotNode, err := subject.Load(lctx, test.link, basicnode.Prototype.Any)
+			qt.Check(t, err, qt.IsNil)
+			qt.Check(t, ipld.DeepEqual(wantNode, gotNode), qt.IsTrue)
+
+			gotNodeRaw, err := subject.LoadRaw(lctx, test.link)
+			qt.Check(t, err, qt.IsNil)
+			qt.Check(t, bytes.Equal(wantNodeRaw, gotNodeRaw), qt.IsTrue)
+
+			gotNode, gotNodeRaw, err = subject.LoadPlusRaw(lctx, test.link, basicnode.Prototype.Any)
+			qt.Check(t, err, qt.IsNil)
+			qt.Check(t, ipld.DeepEqual(wantNode, gotNode), qt.IsTrue)
+			qt.Check(t, bytes.Equal(wantNodeRaw, gotNodeRaw), qt.IsTrue)
+		})
+	}
+}