Blob I/O: limit and expose blob size

Author: joriszwart

blob_io.go

@@ -128,11 +128,20 @@ func (s *SQLiteBlob) Seek(offset int64, whence int) (int64, error) {
 		return 0, errors.New("sqlite.SQLiteBlob.Seek: negative position")
 	}
 
+	if abs > math.MaxInt32 {
+		return 0, errors.New("sqlite3.SQLiteBlob.Seek: overflow position")
+	}
+
 	s.offset = int(abs)
 
 	return abs, nil
 }
 
+// Size returns the size of the blob.
+func (s *SQLiteBlob) Size() int {
+	return s.size
+}
+
 // Close implements the io.Closer interface.
 func (s *SQLiteBlob) Close() error {
 	ret := C.sqlite3_blob_close(s.blob)