Fix code ad add tests

example_test.go

@@ -3,6 +3,7 @@ package rsync_test
 import (
 	"fmt"
 	"io"
+	"log"
 	"strings"
 
 	"github.com/minio/rsync-go"
@@ -20,7 +21,10 @@ func ExampleRsync() {
 		sig = append(sig, bl)
 		return nil
 	}
-	_ = rs.CreateSignature(oldReader, writeSignature)
+	err := rs.CreateSignature(oldReader, writeSignature)
+	if err != nil {
+		log.Fatal(err)
+	}
 
 	var currentReader io.Reader
 	currentReader = strings.NewReader("I am the new content")
@@ -33,13 +37,22 @@ func ExampleRsync() {
 
 	go func() {
 		defer close(opsOut)
-		_ = rs.CreateDelta(currentReader, sig, writeOperation)
+		err := rs.CreateDelta(currentReader, sig, writeOperation)
+		if err != nil {
+			log.Fatal(err)
+		}
 	}()
 
 	var newWriter strings.Builder
-	_, _ = oldReader.Seek(0, io.SeekStart)
+	_, err = oldReader.Seek(0, io.SeekStart)
+	if err != nil {
+		log.Fatal(err)
+	}
 
-	_ = rs.ApplyDelta(&newWriter, oldReader, opsOut)
+	err = rs.ApplyDelta(&newWriter, oldReader, opsOut)
+	if err != nil {
+		log.Fatal(err)
+	}
 
 	fmt.Println(newWriter.String())
 	// Output: I am the new content

fuzzing_test.go

@@ -1,3 +1,12 @@
+// RSync/RDiff implementation.
+//
+// Algorithm found at: http://www.samba.org/~tridge/phd_thesis.pdf
+//
+// Definitions
+//
+//	Source: The final content.
+//	Target: The content to be made into final content.
+//	Signature: The sequence of hashes used to identify the content.
 package rsync_test
 
 import (
@@ -7,11 +16,10 @@ import (
 	"testing"
 
 	"github.com/minio/rsync-go"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
 )
 
 func FuzzSync(f *testing.F) {
+	f.Add(bytes.Repeat([]byte("0"), 8192))
 	f.Fuzz(func(t *testing.T, message []byte) {
 		if len(message) == 0 {
 			return
@@ -26,60 +34,86 @@ func FuzzSync(f *testing.F) {
 			n = len(message)
 		}
 
-		mode := "expand"
-		oldContent := message[:n]
-		newContent := message
-		if rand.IntN(2) == 0 {
+		var mode string
+		var oldContent, newContent []byte
+		switch rand.IntN(4) {
+		case 0:
+			mode = "expand"
+			oldContent = message[:n]
+			newContent = message
+		case 1:
 			mode = "shrink"
 			oldContent = message
 			newContent = message[:n]
+		case 2:
+			mode = "prepend"
+			oldContent = message[n:]
+			newContent = message
+		case 3:
+			m := 1 + rand.IntN(n)
+			if m > n {
+				m = n
+			}
+
+			mode = "mix"
+			oldContent = message[m:n]
+			newContent = message
 		}
 
-		result := sync(t, rs, oldContent, newContent)
-		assert.Equalf(t, newContent, result,
-			"%d,%s:\t%#v\noldContent:\t%#v\nnewContent:\t%#v",
-			rs.BlockSize, mode, message, oldContent, newContent)
+		var buf bytes.Buffer
+		sync(t, rs, &buf, oldContent, newContent)
+		if bytes.Compare(newContent, buf.Bytes()) != 0 {
+			t.Errorf("Not equal: \nexpected : %#v\nactual   : %#v\n\nmessage  : %#v\nblocksize: %d\nmode     : %s",
+				newContent, buf.Bytes(), message, rs.BlockSize, mode)
+		}
 	})
 }
 
-func syncString(t *testing.T, rs *rsync.RSync, oldContent, newContent string) string {
-	return string(sync(t, rs, []byte(oldContent), []byte(newContent)))
+func syncString(t *testing.T, rs *rsync.RSync, w io.Writer, oldContent, newContent string) {
+	sync(t, rs, w, []byte(oldContent), []byte(newContent))
 }
 
-func sync(t *testing.T, rs *rsync.RSync, oldContent, newContent []byte) []byte {
+func sync(t *testing.T, rs *rsync.RSync, w io.Writer, oldContent, newContent []byte) {
 	oldReader := bytes.NewReader(oldContent)
 
 	// here we store the whole signature in a byte slice,
 	// but it could just as well be sent over a network connection for example
-	sig := make([]rsync.BlockHash, 0, 10)
-	writeSignature := func(bl rsync.BlockHash) error {
-		sig = append(sig, bl)
+	signatures := make([]rsync.BlockHash, 0, 10)
+	err := rs.CreateSignature(oldReader, func(bl rsync.BlockHash) error {
+		signatures = append(signatures, bl)
 		return nil
+	})
+	if err != nil {
+		t.Errorf(err.Error())
+		t.FailNow()
 	}
-	err := rs.CreateSignature(oldReader, writeSignature)
-	require.NoError(t, err)
 
 	var currentReader io.Reader = bytes.NewReader(newContent)
-
 	opsOut := make(chan rsync.Operation)
-	writeOperation := func(op rsync.Operation) error {
-		opsOut <- op
-		return nil
-	}
 
 	go func() {
 		defer close(opsOut)
 
-		err := rs.CreateDelta(currentReader, sig, writeOperation)
-		require.NoError(t, err)
+		err := rs.CreateDelta(currentReader, signatures, func(op rsync.Operation) error {
+			opsOut <- op
+			return nil
+		})
+		if err != nil {
+			t.Errorf(err.Error())
+			t.FailNow()
+		}
 	}()
 
-	var buf bytes.Buffer
+	// Already read once for the signatures so we rewind the reader.
 	_, err = oldReader.Seek(0, io.SeekStart)
-	require.NoError(t, err)
-
-	err = rs.ApplyDelta(&buf, oldReader, opsOut)
-	require.NoError(t, err)
+	if err != nil {
+		t.Errorf(err.Error())
+		t.FailNow()
+	}
 
-	return buf.Bytes()
+	err = rs.ApplyDelta(w, oldReader, opsOut)
+	if err != nil {
+		t.Errorf(err.Error())
+		t.FailNow()
+	}
 }

go.mod

@@ -2,14 +2,6 @@ module github.com/minio/rsync-go
 
 go 1.17
 
-require (
-	github.com/minio/highwayhash v1.0.3
-	github.com/stretchr/testify v1.9.0
-)
+require github.com/minio/highwayhash v1.0.3
 
-require (
-	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
-	golang.org/x/sys v0.24.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
-)
+require golang.org/x/sys v0.24.0 // indirect

go.sum

@@ -1,24 +1,5 @@
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/minio/highwayhash v1.0.3 h1:kbnuUMoHYyVl7szWjSxJnxw11k2U709jqFPPmIUyD6Q=
 github.com/minio/highwayhash v1.0.3/go.mod h1:GGYsuwP/fPD6Y9hMiXuapVvlIUEhFhMTh0rxU3ik1LQ=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
-github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
-github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
-github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
-github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
-github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
-github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.24.0 h1:Twjiwq9dn6R1fQcyiK+wQyHWfaz/BJB+YIpzU/Cv3Xg=
 golang.org/x/sys v0.24.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

rsync.go

@@ -311,9 +311,6 @@ func (r *RSync) CreateDelta(source io.Reader, signature []BlockHash, ops Operati
 
 				data.head = validTo
 			}
-			if n == 0 {
-				break
-			}
 		}
 
 		// Set the hash sum window head. Must either be a block size

rsync_test.go

@@ -0,0 +1,95 @@
+// RSync/RDiff implementation.
+//
+// Algorithm found at: http://www.samba.org/~tridge/phd_thesis.pdf
+//
+// Definitions
+//
+//	Source: The final content.
+//	Target: The content to be made into final content.
+//	Signature: The sequence of hashes used to identify the content.
+package rsync_test
+
+import (
+	"bytes"
+	"io"
+	"strings"
+	"testing"
+
+	"github.com/minio/rsync-go"
+)
+
+func Test_Rync(t *testing.T) {
+	tests := []struct {
+		name       string
+		oldContent string
+		newContent string
+		rs         *rsync.RSync
+	}{
+		{
+			name:       "fix: Delta Operation incomplete generation",
+			oldContent: "1234",
+			newContent: "123456789123456",
+			rs: &rsync.RSync{
+				BlockSize: 3,
+			},
+		},
+		{
+			name:       "shrink",
+			oldContent: "123456789123456",
+			newContent: "1234",
+			rs: &rsync.RSync{
+				BlockSize: 3,
+			},
+		},
+		{
+			name:       "prepend",
+			oldContent: "1234",
+			newContent: "567891234561234",
+			rs: &rsync.RSync{
+				BlockSize: 3,
+			},
+		},
+		{
+			name:       "mix",
+			oldContent: "base",
+			newContent: "5678912-base-34561234",
+			rs: &rsync.RSync{
+				BlockSize: 3,
+			},
+		},
+		{
+			name:       "replace",
+			oldContent: "base",
+			newContent: "123456789123456",
+			rs: &rsync.RSync{
+				BlockSize: 3,
+			},
+		},
+		{
+			name:       "mix",
+			oldContent: "base",
+			newContent: "5678912-base-34561234",
+			rs: &rsync.RSync{
+				BlockSize: 3,
+			},
+		},
+	}
+
+	for _, test := range tests {
+		var buf bytes.Buffer
+		syncString(t, test.rs, &buf, test.oldContent, test.newContent)
+		if test.newContent == buf.String() {
+			t.Errorf("Not equal: \nexpected: %s\nactual  : %s\n\nMessage : %s", test.newContent, buf.String(), test.name)
+		}
+	}
+}
+
+func _Test_RyncRAM(t *testing.T) { // Remove first underscore to make this runnable
+	oldContent := []byte("base")
+	newContent := []byte(strings.Repeat("0", 256<<20))
+	rs := &rsync.RSync{}
+
+	for i := 0; i < 10000000; i++ {
+		sync(t, rs, io.Discard, oldContent, newContent)
+	}
+}