gateway-gcs: cleanup minio.sys.temp before deleting the bucket (#4582)

fixes #4560
fixes #4569

cmd/gateway-gcs.go

@@ -41,11 +41,11 @@ const (
 	// gcsMinioMeta is used for multiparts. We have "minio.sys.temp" prefix so that
 	// listing on the GCS lists this entry in the end. Also in the gateway
 	// ListObjects we filter out this entry.
-	gcsMinioPath = "minio.sys.temp"
+	gcsMinioPath = "minio.sys.temp/"
 	// Path where multipart objects are saved.
 	// If we change the backend format we will use a different url path like /multipart/v2
 	// but we will not migrate old data.
-	gcsMinioMultipartPathV1 = gcsMinioPath + "/multipart/v1"
+	gcsMinioMultipartPathV1 = gcsMinioPath + "multipart/v1"
 	// Multipart meta file.
 	gcsMinioMultipartMeta = "gcs.json"
 	// gcs.json version number
@@ -63,11 +63,6 @@ type gcsMultipartMetaV1 struct {
 	Object  string `json:"object"`  // Object name
 }
 
-// Check if object prefix is "ZZZZ_Minio".
-func isGCSPrefix(prefix string) bool {
-	return strings.TrimSuffix(prefix, slashSeparator) == gcsMinioPath
-}
-
 // Returns name of the multipart meta object.
 func gcsMultipartMetaName(uploadID string) string {
 	return fmt.Sprintf("%s/%s/%s", gcsMinioMultipartPathV1, uploadID, gcsMinioMultipartMeta)
@@ -157,28 +152,21 @@ func gcsToObjectError(err error, params ...string) error {
 				Bucket: bucket,
 				Object: object,
 			}
-		} else {
-			err = BucketNotFound{
-				Bucket: bucket,
-			}
+			break
 		}
+		err = BucketNotFound{Bucket: bucket}
 	case "conflict":
 		if message == "You already own this bucket. Please select another name." {
-			err = BucketAlreadyOwnedByYou{
-				Bucket: bucket,
-			}
-		} else if message == "Sorry, that name is not available. Please try a different one." {
-			err = BucketAlreadyExists{
-				Bucket: bucket,
-			}
-		} else {
-			err = BucketNotEmpty{
-				Bucket: bucket,
+			err = BucketAlreadyOwnedByYou{Bucket: bucket}
+			break
 		}
+		if message == "Sorry, that name is not available. Please try a different one." {
+			err = BucketAlreadyExists{Bucket: bucket}
+			break
 		}
+		err = BucketNotEmpty{Bucket: bucket}
 	default:
 		err = fmt.Errorf("Unsupported error reason: %s", reason)
-
 	}
 
 	e.e = err
@@ -294,8 +282,48 @@ func (l *gcsGateway) ListBuckets() ([]BucketInfo, error) {
 	return b, nil
 }
 
-// DeleteBucket delete a bucket on GCS
+// DeleteBucket delete a bucket on GCS.
 func (l *gcsGateway) DeleteBucket(bucket string) error {
+	itObject := l.client.Bucket(bucket).Objects(l.ctx, &storage.Query{Delimiter: slashSeparator, Versions: false})
+	// We list the bucket and if we find any objects we return BucketNotEmpty error. If we
+	// find only "minio.sys.temp/" then we remove it before deleting the bucket.
+	gcsMinioPathFound := false
+	nonGCSMinioPathFound := false
+	for {
+		objAttrs, err := itObject.Next()
+		if err == iterator.Done {
+			break
+		}
+		if err != nil {
+			return gcsToObjectError(traceError(err))
+		}
+		if objAttrs.Prefix == gcsMinioPath {
+			gcsMinioPathFound = true
+			continue
+		}
+		nonGCSMinioPathFound = true
+		break
+	}
+	if nonGCSMinioPathFound {
+		return gcsToObjectError(traceError(BucketNotEmpty{}))
+	}
+	if gcsMinioPathFound {
+		// Remove minio.sys.temp before deleting the bucket.
+		itObject = l.client.Bucket(bucket).Objects(l.ctx, &storage.Query{Versions: false, Prefix: gcsMinioPath})
+		for {
+			objAttrs, err := itObject.Next()
+			if err == iterator.Done {
+				break
+			}
+			if err != nil {
+				return gcsToObjectError(traceError(err))
+			}
+			err = l.client.Bucket(bucket).Object(objAttrs.Name).Delete(l.ctx)
+			if err != nil {
+				return gcsToObjectError(traceError(err))
+			}
+		}
+	}
 	err := l.client.Bucket(bucket).Delete(l.ctx)
 	return gcsToObjectError(traceError(err), bucket)
 }
@@ -361,10 +389,8 @@ func (l *gcsGateway) ListObjects(bucket string, prefix string, marker string, de
 			// if that one next object is our hidden
 			// metadata folder, then just break
 			// otherwise we've truncated the output
-
 			attrs, _ := it.Next()
-			if attrs == nil {
-			} else if isGCSPrefix(attrs.Prefix) {
+			if attrs != nil && attrs.Prefix == gcsMinioPath {
 				break
 			}
 
@@ -375,19 +401,31 @@ func (l *gcsGateway) ListObjects(bucket string, prefix string, marker string, de
 		attrs, err := it.Next()
 		if err == iterator.Done {
 			break
-		} else if err != nil {
+		}
+		if err != nil {
 			return ListObjectsInfo{}, gcsToObjectError(traceError(err), bucket, prefix)
 		}
 
 		nextMarker = toGCSPageToken(attrs.Name)
 
-		if isGCSPrefix(attrs.Prefix) {
-			// we don't return our metadata prefix
+		if attrs.Prefix == gcsMinioPath {
+			// We don't return our metadata prefix.
+			continue
+		}
+		if !strings.HasPrefix(prefix, gcsMinioPath) {
+			// If client lists outside gcsMinioPath then we filter out gcsMinioPath/* entries.
+			// But if the client lists inside gcsMinioPath then we return the entries in gcsMinioPath/
+			// which will be helpful to observe the "directory structure" for debugging purposes.
+			if strings.HasPrefix(attrs.Prefix, gcsMinioPath) ||
+				strings.HasPrefix(attrs.Name, gcsMinioPath) {
 				continue
-		} else if attrs.Prefix != "" {
+			}
+		}
+		if attrs.Prefix != "" {
 			prefixes = append(prefixes, attrs.Prefix)
 			continue
-		} else if !gcsMarker && attrs.Name <= marker {
+		}
+		if !gcsMarker && attrs.Name <= marker {
 			// if user supplied a marker don't append
 			// objects until we reach marker (and skip it).
 			continue
@@ -851,7 +889,8 @@ func (l *gcsGateway) SetBucketPolicies(bucket string, policyInfo policy.BucketAc
 
 	if len(policies) != 1 {
 		return traceError(NotImplemented{})
-	} else if policies[0].Prefix != prefix {
+	}
+	if policies[0].Prefix != prefix {
 		return traceError(NotImplemented{})
 	}
 

cmd/gateway-gcs_test.go

@@ -99,41 +99,6 @@ func TestValidGCSProjectID(t *testing.T) {
 	}
 }
 
-// Test for isGCSPrefix
-func TestIsGCSPrefix(t *testing.T) {
-	testCases := []struct {
-		prefix      string
-		expectedRes bool
-	}{
-		// Regular prefix without a trailing slash
-		{
-			prefix:      "hello",
-			expectedRes: false,
-		},
-		// Regular prefix with a trailing slash
-		{
-			prefix:      "hello/",
-			expectedRes: false,
-		},
-		// GCS prefix without a trailing slash
-		{
-			prefix:      gcsMinioPath,
-			expectedRes: true,
-		},
-		// GCS prefix with a trailing slash
-		{
-			prefix:      gcsMinioPath + "/",
-			expectedRes: true,
-		},
-	}
-
-	for i, tc := range testCases {
-		if actualRes := isGCSPrefix(tc.prefix); actualRes != tc.expectedRes {
-			t.Errorf("%d: Expected isGCSPrefix to return %v but got %v", i, tc.expectedRes, actualRes)
-		}
-	}
-}
-
 // Test for isGCSMarker.
 func TestIsGCSMarker(t *testing.T) {
 	testCases := []struct {