size_t

       MongoDB, Inc

       2009-present, MongoDB, Inc.

1.30.4                                            Jun 08, 2025                         BSON_WRITER_GET_LENGTH(3)

       Fetches  the  current  length  of  the content written by the buffer (including the initial offset). This
       includes a partly written document currently being written.

       This is useful if you want to check to see if you've passed a given memory boundary that cannot  be  sent
       in a packet. See bson_writer_rollback() to abort the current document being written.

       • writer: A bson_writer_t.

       The length of the underlying buffer.

          size_t
          bson_writer_get_length (bson_writer_t *writer);