feat(linksystem): add option to disable hash on read

Have boolean that specifies whether the storage is trusted. if it is, skip hashing on reads

linking.go

@@ -56,6 +56,9 @@ func (lsys *LinkSystem) Fill(lnkCtx LinkContext, lnk Link, na NodeAssembler) err
 	if err != nil {
 		return err
 	}
+	if lsys.TrustedStorage {
+		return decoder(na, reader)
+	}
 	tee := io.TeeReader(reader, hasher)
 	decodeErr := decoder(na, tee)
 	if decodeErr != nil { // It is important to security to check the hash before returning any other observation about the content.

linksystem.go

@@ -32,6 +32,7 @@ type LinkSystem struct {
 	HasherChooser      func(LinkPrototype) (hash.Hash, error)
 	StorageWriteOpener BlockWriteOpener
 	StorageReadOpener  BlockReadOpener
+	TrustedStorage     bool
 }
 
 // The following two types define the two directions of transform that a codec can be expected to perform: