Ejemplo n.º 1
0
func TestCallbacksWork(t *testing.T) {
	fake := new(FakeStream)

	var sent int64
	var recv int64

	sentCB := func(n int64, proto protocol.ID, p peer.ID) {
		sent += n
	}

	recvCB := func(n int64, proto protocol.ID, p peer.ID) {
		recv += n
	}

	ms := newMeteredStream(fake, protocol.ID("TEST"), peer.ID("PEER"), recvCB, sentCB)

	toWrite := int64(100000)
	toRead := int64(100000)

	fake.ReadBuf = io.LimitReader(u.NewTimeSeededRand(), toRead)
	writeData := io.LimitReader(u.NewTimeSeededRand(), toWrite)

	n, err := io.Copy(ms, writeData)
	if err != nil {
		t.Fatal(err)
	}

	if n != toWrite {
		t.Fatal("incorrect write amount")
	}

	if toWrite != sent {
		t.Fatal("incorrectly reported writes", toWrite, sent)
	}

	n, err = io.Copy(ioutil.Discard, ms)
	if err != nil {
		t.Fatal(err)
	}

	if n != toRead {
		t.Fatal("incorrect read amount")
	}

	if toRead != recv {
		t.Fatal("incorrectly reported reads")
	}
}
Ejemplo n.º 2
0
func TestBalancedDag(t *testing.T) {
	ds := mdtest.Mock()
	buf := make([]byte, 10000)
	u.NewTimeSeededRand().Read(buf)
	r := bytes.NewReader(buf)

	nd, err := BuildDagFromReader(ds, chunk.DefaultSplitter(r), nil)
	if err != nil {
		t.Fatal(err)
	}

	dr, err := uio.NewDagReader(context.Background(), nd, ds)
	if err != nil {
		t.Fatal(err)
	}

	out, err := ioutil.ReadAll(dr)
	if err != nil {
		t.Fatal(err)
	}

	if !bytes.Equal(out, buf) {
		t.Fatal("bad read")
	}
}
Ejemplo n.º 3
0
func TestRabinChunking(t *testing.T) {
	data := make([]byte, 1024*1024*16)
	util.NewTimeSeededRand().Read(data)

	r := NewRabin(bytes.NewReader(data), 1024*256)

	var chunks [][]byte

	for {
		chunk, err := r.NextBytes()
		if err != nil {
			if err == io.EOF {
				break
			}
			t.Fatal(err)
		}

		chunks = append(chunks, chunk)
	}

	fmt.Printf("average block size: %d\n", len(data)/len(chunks))

	unchunked := bytes.Join(chunks, nil)
	if !bytes.Equal(unchunked, data) {
		fmt.Printf("%d %d\n", len(unchunked), len(data))
		t.Fatal("data was chunked incorrectly")
	}
}
Ejemplo n.º 4
0
func randNode() (*merkledag.Node, key.Key) {
	node := new(merkledag.Node)
	node.Data = make([]byte, 32)
	util.NewTimeSeededRand().Read(node.Data)
	k, _ := node.Key()
	return node, k
}
Ejemplo n.º 5
0
func randBuf(t *testing.T, size int) []byte {
	buf := make([]byte, size)
	if _, err := u.NewTimeSeededRand().Read(buf); err != nil {
		t.Fatal("failed to read enough randomness")
	}
	return buf
}
Ejemplo n.º 6
0
func testFileConsistency(t *testing.T, bs chunk.SplitterGen, nbytes int) {
	should := make([]byte, nbytes)
	u.NewTimeSeededRand().Read(should)

	read := bytes.NewReader(should)
	ds := mdtest.Mock()
	nd, err := buildTestDag(ds, bs(read))
	if err != nil {
		t.Fatal(err)
	}

	r, err := uio.NewDagReader(context.Background(), nd, ds)
	if err != nil {
		t.Fatal(err)
	}

	out, err := ioutil.ReadAll(r)
	if err != nil {
		t.Fatal(err)
	}

	err = arrComp(out, should)
	if err != nil {
		t.Fatal(err)
	}
}
Ejemplo n.º 7
0
func TestBuilderConsistency(t *testing.T) {
	nbytes := 100000
	buf := new(bytes.Buffer)
	io.CopyN(buf, u.NewTimeSeededRand(), int64(nbytes))
	should := dup(buf.Bytes())
	dagserv := mdtest.Mock()
	nd, err := buildTestDag(dagserv, chunk.DefaultSplitter(buf))
	if err != nil {
		t.Fatal(err)
	}
	r, err := uio.NewDagReader(context.Background(), nd, dagserv)
	if err != nil {
		t.Fatal(err)
	}

	out, err := ioutil.ReadAll(r)
	if err != nil {
		t.Fatal(err)
	}

	err = arrComp(out, should)
	if err != nil {
		t.Fatal(err)
	}
}
Ejemplo n.º 8
0
func randNode() (*mdag.Node, key.Key) {
	nd := new(mdag.Node)
	nd.Data = make([]byte, 32)
	util.NewTimeSeededRand().Read(nd.Data)
	k, _ := nd.Key()
	return nd, k
}
Ejemplo n.º 9
0
func BenchmarkDagmodWrite(b *testing.B) {
	b.StopTimer()
	dserv, pins := getMockDagServ(b)
	_, n := getNode(b, dserv, 0, pins)
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	wrsize := 4096

	dagmod, err := NewDagModifier(ctx, n, dserv, pins, sizeSplitterGen(512))
	if err != nil {
		b.Fatal(err)
	}

	buf := make([]byte, b.N*wrsize)
	u.NewTimeSeededRand().Read(buf)
	b.StartTimer()
	b.SetBytes(int64(wrsize))
	for i := 0; i < b.N; i++ {
		n, err := dagmod.Write(buf[i*wrsize : (i+1)*wrsize])
		if err != nil {
			b.Fatal(err)
		}
		if n != wrsize {
			b.Fatal("Wrote bad size")
		}
	}
}
Ejemplo n.º 10
0
func TestIndirectBlocks(t *testing.T) {
	splitter := chunk.SizeSplitterGen(512)
	nbytes := 1024 * 1024
	buf := make([]byte, nbytes)
	u.NewTimeSeededRand().Read(buf)

	read := bytes.NewReader(buf)

	ds := mdtest.Mock()
	dag, err := buildTestDag(ds, splitter(read))
	if err != nil {
		t.Fatal(err)
	}

	reader, err := uio.NewDagReader(context.Background(), dag, ds)
	if err != nil {
		t.Fatal(err)
	}

	out, err := ioutil.ReadAll(reader)
	if err != nil {
		t.Fatal(err)
	}

	if !bytes.Equal(out, buf) {
		t.Fatal("Not equal!")
	}
}
Ejemplo n.º 11
0
func TestSeekEndSingleBlockFile(t *testing.T) {
	nbytes := int64(100)
	should := make([]byte, nbytes)
	u.NewTimeSeededRand().Read(should)

	read := bytes.NewReader(should)
	ds := mdtest.Mock()
	nd, err := buildTestDag(ds, chunk.NewSizeSplitter(read, 5000))
	if err != nil {
		t.Fatal(err)
	}

	rs, err := uio.NewDagReader(context.Background(), nd, ds)
	if err != nil {
		t.Fatal(err)
	}

	seeked, err := rs.Seek(0, os.SEEK_END)
	if err != nil {
		t.Fatal(err)
	}
	if seeked != nbytes {
		t.Fatal("Failed to seek to end")
	}
}
Ejemplo n.º 12
0
// RandPeerID generates random "valid" peer IDs. it does not NEED to generate
// keys because it is as if we lost the key right away. fine to read randomness
// and hash it. to generate proper keys and corresponding PeerID, use:
//  sk, pk, _ := testutil.RandKeyPair()
//  id, _ := peer.IDFromPublicKey(pk)
func RandPeerID() (peer.ID, error) {
	buf := make([]byte, 16)
	if _, err := io.ReadFull(u.NewTimeSeededRand(), buf); err != nil {
		return "", err
	}
	h := u.Hash(buf)
	return peer.ID(h), nil
}
Ejemplo n.º 13
0
func RandTestBogusPrivateKey() (TestBogusPrivateKey, error) {
	r := u.NewTimeSeededRand()
	k := make([]byte, 5)
	if _, err := io.ReadFull(r, k); err != nil {
		return nil, err
	}
	return TestBogusPrivateKey(k), nil
}
Ejemplo n.º 14
0
func getTrickleDag(t testing.TB, size int64, blksize int64) (*dag.Node, dag.DAGService) {
	ds := mdtest.Mock()
	r := io.LimitReader(u.NewTimeSeededRand(), size)
	nd, err := BuildTrickleDagFromReader(ds, chunk.NewSizeSplitter(r, blksize), nil)
	if err != nil {
		t.Fatal(err)
	}
	return nd, ds
}
Ejemplo n.º 15
0
func TestMetadata(t *testing.T) {
	ctx := context.Background()
	// Make some random node
	ds := getDagserv(t)
	data := make([]byte, 1000)
	u.NewTimeSeededRand().Read(data)
	r := bytes.NewReader(data)
	nd, err := importer.BuildDagFromReader(ds, chunk.DefaultSplitter(r), nil)
	if err != nil {
		t.Fatal(err)
	}

	k, err := nd.Key()
	if err != nil {
		t.Fatal(err)
	}

	m := new(ft.Metadata)
	m.MimeType = "THIS IS A TEST"

	// Such effort, many compromise
	ipfsnode := &core.IpfsNode{DAG: ds}

	mdk, err := AddMetadataTo(ipfsnode, k.B58String(), m)
	if err != nil {
		t.Fatal(err)
	}

	rec, err := Metadata(ipfsnode, mdk)
	if err != nil {
		t.Fatal(err)
	}
	if rec.MimeType != m.MimeType {
		t.Fatalf("something went wrong in conversion: '%s' != '%s'", rec.MimeType, m.MimeType)
	}

	retnode, err := ds.Get(ctx, key.B58KeyDecode(mdk))
	if err != nil {
		t.Fatal(err)
	}

	ndr, err := uio.NewDagReader(ctx, retnode, ds)
	if err != nil {
		t.Fatal(err)
	}

	out, err := ioutil.ReadAll(ndr)
	if err != nil {
		t.Fatal(err)
	}

	if !bytes.Equal(out, data) {
		t.Fatal("read incorrect data")
	}
}
Ejemplo n.º 16
0
func randObj(t *testing.T, nd *core.IpfsNode, size int64) (*dag.Node, []byte) {
	buf := make([]byte, size)
	u.NewTimeSeededRand().Read(buf)
	read := bytes.NewReader(buf)
	obj, err := importer.BuildTrickleDagFromReader(nd.DAG, chunk.DefaultSplitter(read), nil)
	if err != nil {
		t.Fatal(err)
	}

	return obj, buf
}
Ejemplo n.º 17
0
func getTestDag(t *testing.T, ds dag.DAGService, size int64, blksize int64) (*dag.Node, []byte) {
	data := make([]byte, size)
	u.NewTimeSeededRand().Read(data)
	r := bytes.NewReader(data)

	nd, err := buildTestDag(ds, chunk.NewSizeSplitter(r, blksize))
	if err != nil {
		t.Fatal(err)
	}

	return nd, data
}
Ejemplo n.º 18
0
func TestMultiWrite(t *testing.T) {
	dserv, pins := getMockDagServ(t)
	_, n := getNode(t, dserv, 0, pins)

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	dagmod, err := NewDagModifier(ctx, n, dserv, pins, sizeSplitterGen(512))
	if err != nil {
		t.Fatal(err)
	}

	data := make([]byte, 4000)
	u.NewTimeSeededRand().Read(data)

	for i := 0; i < len(data); i++ {
		n, err := dagmod.WriteAt(data[i:i+1], int64(i))
		if err != nil {
			t.Fatal(err)
		}
		if n != 1 {
			t.Fatal("Somehow wrote the wrong number of bytes! (n != 1)")
		}

		size, err := dagmod.Size()
		if err != nil {
			t.Fatal(err)
		}

		if size != int64(i+1) {
			t.Fatal("Size was reported incorrectly")
		}
	}
	nd, err := dagmod.GetNode()
	if err != nil {
		t.Fatal(err)
	}

	read, err := uio.NewDagReader(context.Background(), nd, dserv)
	if err != nil {
		t.Fatal(err)
	}
	rbuf, err := ioutil.ReadAll(read)
	if err != nil {
		t.Fatal(err)
	}

	err = arrComp(rbuf, data)
	if err != nil {
		t.Fatal(err)
	}
}
Ejemplo n.º 19
0
// This test appends one byte at a time to an empty file
func TestMultipleAppends(t *testing.T) {
	ds := mdtest.Mock()

	// TODO: fix small size appends and make this number bigger
	nbytes := int64(1000)
	should := make([]byte, nbytes)
	u.NewTimeSeededRand().Read(should)

	read := bytes.NewReader(nil)
	nd, err := buildTestDag(ds, chunk.NewSizeSplitter(read, 500))
	if err != nil {
		t.Fatal(err)
	}

	dbp := &h.DagBuilderParams{
		Dagserv:  ds,
		Maxlinks: 4,
	}

	spl := chunk.SizeSplitterGen(500)

	ctx := context.Background()
	for i := 0; i < len(should); i++ {
		blks, errs := chunk.Chan(spl(bytes.NewReader(should[i : i+1])))

		nnode, err := TrickleAppend(ctx, nd, dbp.New(blks, errs))
		if err != nil {
			t.Fatal(err)
		}

		err = VerifyTrickleDagStructure(nnode, ds, dbp.Maxlinks, layerRepeat)
		if err != nil {
			t.Fatal(err)
		}

		fread, err := uio.NewDagReader(ctx, nnode, ds)
		if err != nil {
			t.Fatal(err)
		}

		out, err := ioutil.ReadAll(fread)
		if err != nil {
			t.Fatal(err)
		}

		err = arrComp(out, should[:i+1])
		if err != nil {
			t.Fatal(err)
		}
	}
}
Ejemplo n.º 20
0
func TestAppend(t *testing.T) {
	nbytes := int64(128 * 1024)
	should := make([]byte, nbytes)
	u.NewTimeSeededRand().Read(should)

	// Reader for half the bytes
	read := bytes.NewReader(should[:nbytes/2])
	ds := mdtest.Mock()
	nd, err := buildTestDag(ds, chunk.NewSizeSplitter(read, 500))
	if err != nil {
		t.Fatal(err)
	}

	dbp := &h.DagBuilderParams{
		Dagserv:  ds,
		Maxlinks: h.DefaultLinksPerBlock,
	}

	r := bytes.NewReader(should[nbytes/2:])
	blks, errs := chunk.Chan(chunk.NewSizeSplitter(r, 500))

	ctx := context.Background()
	nnode, err := TrickleAppend(ctx, nd, dbp.New(blks, errs))
	if err != nil {
		t.Fatal(err)
	}

	err = VerifyTrickleDagStructure(nnode, ds, dbp.Maxlinks, layerRepeat)
	if err != nil {
		t.Fatal(err)
	}

	fread, err := uio.NewDagReader(ctx, nnode, ds)
	if err != nil {
		t.Fatal(err)
	}

	out, err := ioutil.ReadAll(fread)
	if err != nil {
		t.Fatal(err)
	}

	err = arrComp(out, should)
	if err != nil {
		t.Fatal(err)
	}
}
Ejemplo n.º 21
0
func newSender() (chan sendChans, func(s inet.Stream)) {
	scc := make(chan sendChans)
	return scc, func(s inet.Stream) {
		sc := newSendChans()
		scc <- sc

		defer func() {
			s.Close()
			sc.closed <- struct{}{}
		}()

		buf := make([]byte, 65536)
		buf2 := make([]byte, 65536)
		u.NewTimeSeededRand().Read(buf)

		for {
			select {
			case <-sc.close_:
				return
			case <-sc.send:
			}

			// send a randomly sized subchunk
			from := rand.Intn(len(buf) / 2)
			to := rand.Intn(len(buf) / 2)
			sendbuf := buf[from : from+to]

			log.Debugf("sender sending %d bytes", len(sendbuf))
			n, err := s.Write(sendbuf)
			if err != nil {
				log.Debug("sender error. exiting:", err)
				return
			}

			log.Debugf("sender wrote %d bytes", n)
			sc.sent <- struct{}{}

			if n, err = io.ReadFull(s, buf2[:len(sendbuf)]); err != nil {
				log.Debug("sender error. failed to read:", err)
				return
			}

			log.Debugf("sender read %d bytes", n)
			sc.read <- struct{}{}
		}
	}
}
Ejemplo n.º 22
0
func testModWrite(t *testing.T, beg, size uint64, orig []byte, dm *DagModifier) []byte {
	newdata := make([]byte, size)
	r := u.NewTimeSeededRand()
	r.Read(newdata)

	if size+beg > uint64(len(orig)) {
		orig = append(orig, make([]byte, (size+beg)-uint64(len(orig)))...)
	}
	copy(orig[beg:], newdata)

	nmod, err := dm.WriteAt(newdata, int64(beg))
	if err != nil {
		t.Fatal(err)
	}

	if nmod != int(size) {
		t.Fatalf("Mod length not correct! %d != %d", nmod, size)
	}

	nd, err := dm.GetNode()
	if err != nil {
		t.Fatal(err)
	}

	err = trickle.VerifyTrickleDagStructure(nd, dm.dagserv, h.DefaultLinksPerBlock, 4)
	if err != nil {
		t.Fatal(err)
	}

	rd, err := uio.NewDagReader(context.Background(), nd, dm.dagserv)
	if err != nil {
		t.Fatal(err)
	}

	after, err := ioutil.ReadAll(rd)
	if err != nil {
		t.Fatal(err)
	}

	err = arrComp(after, orig)
	if err != nil {
		t.Fatal(err)
	}
	return orig
}
Ejemplo n.º 23
0
func TestSeekingStress(t *testing.T) {
	nbytes := int64(1024 * 1024)
	should := make([]byte, nbytes)
	u.NewTimeSeededRand().Read(should)

	read := bytes.NewReader(should)
	ds := mdtest.Mock()
	nd, err := buildTestDag(ds, chunk.NewSizeSplitter(read, 1000))
	if err != nil {
		t.Fatal(err)
	}

	rs, err := uio.NewDagReader(context.Background(), nd, ds)
	if err != nil {
		t.Fatal(err)
	}

	testbuf := make([]byte, nbytes)
	for i := 0; i < 50; i++ {
		offset := mrand.Intn(int(nbytes))
		l := int(nbytes) - offset
		n, err := rs.Seek(int64(offset), os.SEEK_SET)
		if err != nil {
			t.Fatal(err)
		}
		if n != int64(offset) {
			t.Fatal("Seek failed to move to correct position")
		}

		nread, err := rs.Read(testbuf[:l])
		if err != nil {
			t.Fatal(err)
		}
		if nread != l {
			t.Fatal("Failed to read enough bytes")
		}

		err = arrComp(testbuf[:l], should[offset:offset+l])
		if err != nil {
			t.Fatal(err)
		}
	}

}
Ejemplo n.º 24
0
func TestRabinChunkReuse(t *testing.T) {
	data := make([]byte, 1024*1024*16)
	util.NewTimeSeededRand().Read(data)

	ch1 := chunkData(t, data[1000:])
	ch2 := chunkData(t, data)

	var extra int
	for k, _ := range ch2 {
		_, ok := ch1[k]
		if !ok {
			extra++
		}
	}

	if extra > 2 {
		t.Log("too many spare chunks made")
	}
}
Ejemplo n.º 25
0
func getNode(t testing.TB, dserv mdag.DAGService, size int64, pinner pin.ManualPinner) ([]byte, *mdag.Node) {
	in := io.LimitReader(u.NewTimeSeededRand(), size)
	node, err := imp.BuildTrickleDagFromReader(dserv, sizeSplitterGen(500)(in), imp.BasicPinnerCB(pinner))
	if err != nil {
		t.Fatal(err)
	}

	dr, err := uio.NewDagReader(context.Background(), node, dserv)
	if err != nil {
		t.Fatal(err)
	}

	b, err := ioutil.ReadAll(dr)
	if err != nil {
		t.Fatal(err)
	}

	return b, node
}
Ejemplo n.º 26
0
func TestSeekToAlmostBegin(t *testing.T) {
	nbytes := int64(10 * 1024)
	should := make([]byte, nbytes)
	u.NewTimeSeededRand().Read(should)

	read := bytes.NewReader(should)
	ds := mdtest.Mock()
	nd, err := buildTestDag(ds, chunk.NewSizeSplitter(read, 500))
	if err != nil {
		t.Fatal(err)
	}

	rs, err := uio.NewDagReader(context.Background(), nd, ds)
	if err != nil {
		t.Fatal(err)
	}

	n, err := io.CopyN(ioutil.Discard, rs, 1024*4)
	if err != nil {
		t.Fatal(err)
	}
	if n != 4096 {
		t.Fatal("Copy didnt copy enough bytes")
	}

	seeked, err := rs.Seek(1, os.SEEK_SET)
	if err != nil {
		t.Fatal(err)
	}
	if seeked != 1 {
		t.Fatal("Failed to seek to almost beginning")
	}

	out, err := ioutil.ReadAll(rs)
	if err != nil {
		t.Fatal(err)
	}

	err = arrComp(out, should[1:])
	if err != nil {
		t.Fatal(err)
	}
}
Ejemplo n.º 27
0
func TestWriteNewFile(t *testing.T) {
	dserv, pins := getMockDagServ(t)
	_, n := getNode(t, dserv, 0, pins)

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	dagmod, err := NewDagModifier(ctx, n, dserv, pins, sizeSplitterGen(512))
	if err != nil {
		t.Fatal(err)
	}

	towrite := make([]byte, 2000)
	u.NewTimeSeededRand().Read(towrite)

	nw, err := dagmod.Write(towrite)
	if err != nil {
		t.Fatal(err)
	}
	if nw != len(towrite) {
		t.Fatal("Wrote wrong amount")
	}

	nd, err := dagmod.GetNode()
	if err != nil {
		t.Fatal(err)
	}

	read, err := uio.NewDagReader(ctx, nd, dserv)
	if err != nil {
		t.Fatal(err)
	}

	data, err := ioutil.ReadAll(read)
	if err != nil {
		t.Fatal(err)
	}

	if err := arrComp(data, towrite); err != nil {
		t.Fatal(err)
	}
}
Ejemplo n.º 28
0
func TestSeekingConsistency(t *testing.T) {
	nbytes := int64(128 * 1024)
	should := make([]byte, nbytes)
	u.NewTimeSeededRand().Read(should)

	read := bytes.NewReader(should)
	ds := mdtest.Mock()
	nd, err := buildTestDag(ds, chunk.NewSizeSplitter(read, 500))
	if err != nil {
		t.Fatal(err)
	}

	rs, err := uio.NewDagReader(context.Background(), nd, ds)
	if err != nil {
		t.Fatal(err)
	}

	out := make([]byte, nbytes)

	for coff := nbytes - 4096; coff >= 0; coff -= 4096 {
		t.Log(coff)
		n, err := rs.Seek(coff, os.SEEK_SET)
		if err != nil {
			t.Fatal(err)
		}
		if n != coff {
			t.Fatal("wasnt able to seek to the right position")
		}
		nread, err := rs.Read(out[coff : coff+4096])
		if err != nil {
			t.Fatal(err)
		}
		if nread != 4096 {
			t.Fatal("didnt read the correct number of bytes")
		}
	}

	err = arrComp(out, should)
	if err != nil {
		t.Fatal(err)
	}
}
Ejemplo n.º 29
0
func ping(s inet.Stream) (time.Duration, error) {
	buf := make([]byte, PingSize)
	u.NewTimeSeededRand().Read(buf)

	before := time.Now()
	_, err := s.Write(buf)
	if err != nil {
		return 0, err
	}

	rbuf := make([]byte, PingSize)
	_, err = io.ReadFull(s, rbuf)
	if err != nil {
		return 0, err
	}

	if !bytes.Equal(buf, rbuf) {
		return 0, errors.New("ping packet was incorrect!")
	}

	return time.Now().Sub(before), nil
}
Ejemplo n.º 30
0
func TestLargeWriteChunks(t *testing.T) {
	dserv, pins := getMockDagServ(t)
	_, n := getNode(t, dserv, 0, pins)

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	dagmod, err := NewDagModifier(ctx, n, dserv, pins, sizeSplitterGen(512))
	if err != nil {
		t.Fatal(err)
	}

	wrsize := 1000
	datasize := 10000000
	data := make([]byte, datasize)

	u.NewTimeSeededRand().Read(data)

	for i := 0; i < datasize/wrsize; i++ {
		n, err := dagmod.WriteAt(data[i*wrsize:(i+1)*wrsize], int64(i*wrsize))
		if err != nil {
			t.Fatal(err)
		}
		if n != wrsize {
			t.Fatal("failed to write buffer")
		}
	}

	out, err := ioutil.ReadAll(dagmod)
	if err != nil {
		t.Fatal(err)
	}

	if err = arrComp(out, data); err != nil {
		t.Fatal(err)
	}

}