fix: return the entire blob size in patch upload response

regclient/regclient#961
opencontainers/distribution-spec#581

Previously, zot returned the size of the currently uploaded chunk.
Other registries the size of the entire blob.

Align with the latter behavior.

Signed-off-by: Ramkumar Chinchani <rchincha.dev@gmail.com>

Author: rchincha

pkg/storage/imagestore/imagestore.go

@@ -943,7 +943,9 @@ func (is *ImageStore) PutBlobChunk(repo, uuid string, from, to int64,
 
 	defer file.Close()
 
-	if from != file.Size() {
+	fsize := file.Size()
+
+	if from != fsize {
 		is.log.Error().Int64("expected", from).Int64("actual", file.Size()).
 			Msg("invalid range start for blob upload")
 
@@ -952,7 +954,7 @@ func (is *ImageStore) PutBlobChunk(repo, uuid string, from, to int64,
 
 	n, err := io.Copy(file, body)
 
-	return n, err
+	return n + fsize, err
 }
 
 // BlobUploadInfo returns the current blob size in bytes.