[#XX] debug: debug

Signed-off-by: Airat Arifullin <a.arifullin@yadro.com>

object/patcher/patcher.go

@@ -84,6 +84,8 @@ type Params struct {
 	// The size of the buffer used by the original payload range reader.
 	// If it's set to <=0, then `DefaultReaderBufferSize` is used.
 	ReaderBufferSize int
+
+	OriginalPayloadSize uint64
 }
 
 func New(prm Params) PatchApplier {
@@ -99,7 +101,7 @@ func New(prm Params) PatchApplier {
 
 		hdr: prm.Header,
 
-		originalPayloadSize: prm.Header.PayloadSize(),
+		originalPayloadSize: prm.OriginalPayloadSize,
 
 		readerBuffSize: readerBufferSize,
 	}
@@ -169,6 +171,7 @@ func (p *patcher) Close(ctx context.Context) (PatchRes, error) {
 }
 
 func (p *patcher) copyRange(ctx context.Context, rng *objectSDK.Range) error {
+	var totalWritten int
 	rdr := p.rangeProvider.GetRange(ctx, rng)
 	for {
 		buffOrigPayload := make([]byte, p.readerBuffSize)
@@ -178,10 +181,11 @@ func (p *patcher) copyRange(ctx context.Context, rng *objectSDK.Range) error {
 				return fmt.Errorf("read: %w", readErr)
 			}
 		}
-		_, wrErr := p.objectWriter.Write(ctx, buffOrigPayload[:n])
+		wb, wrErr := p.objectWriter.Write(ctx, buffOrigPayload[:n])
 		if wrErr != nil {
 			return fmt.Errorf("write: %w", wrErr)
 		}
+		totalWritten += wb
 		if readErr == io.EOF {
 			break
 		}

object/patcher/patcher_test.go

@@ -533,6 +533,37 @@ func TestPatch(t *testing.T) {
 			originalObjectPayload: []byte("abcdefghijklmnop"),
 			patchedPayload:        []byte("abcdefgh123lmnop"),
 		},
+		{
+			name: "starting from the same offset",
+			patches: []objectSDK.Patch{
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(5, 8),
+						Chunk: []byte("12"),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(13, 0),
+						Chunk: []byte("34"),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(13, 0),
+						Chunk: []byte("56"),
+					},
+				},
+				{
+					PayloadPatch: &objectSDK.PayloadPatch{
+						Range: rangeWithOffestWithLength(13, 0),
+						Chunk: []byte("78"),
+					},
+				},
+			},
+			originalObjectPayload: []byte("abcdefghabcdefgh"),
+			patchedPayload:        []byte("abcdefgh123lmnop"),
+		},
 		{
 			name: "a few patches: various modifiactions",
 			patches: []objectSDK.Patch{