feat: add NewFileBucket func

pmtiles/bucket.go

@@ -72,7 +72,12 @@
 	path string
 }
 
+// NewFileBucket initializes a FileBucket and returns a new instance
+func NewFileBucket(path string) *FileBucket {
+	return &FileBucket{path: path}
+}
+
 func (b FileBucket) NewRangeReader(ctx context.Context, key string, offset, length int64) (io.ReadCloser, error) {
 	body, _, _, err := b.NewRangeReaderEtag(ctx, key, offset, length, "")
 	return body, err
 }
@@ -102,7 +107,7 @@
 	return hasherToEtag(hasher)
 }
 
 func (b FileBucket) NewRangeReaderEtag(_ context.Context, key string, offset, length int64, etag string) (io.ReadCloser, string, int, error) {
 	name := filepath.Join(b.path, key)
 	file, err := os.Open(name)
 	defer file.Close()
@@ -128,7 +133,7 @@
 	return io.NopCloser(bytes.NewReader(result)), newEtag, 206, nil
 }
 
 func (b FileBucket) Close() error {
 	return nil
 }
 
@@ -274,7 +279,7 @@
 			fileprotocol += "/"
 		}
 		path := strings.Replace(bucketURL, fileprotocol, "", 1)
-		bucket := FileBucket{filepath.FromSlash(path)}
+		bucket := NewFileBucket(filepath.FromSlash(path))
 		return bucket, nil
 	}
 	bucket, err := blob.OpenBucket(ctx, bucketURL)