CL_ABAP_ZIP not creating proper archive - incorrect CRC?

Question

Hello,
I am using CL_ABAP_ZIP to upload zipped archive (it's a XSLX with zipped XML's), modifying one of the contained files, zipping it back and downloading to PC. It is opened by Excel application, but with a message that it's a damaged archive (values inside are OK). If I rebuild/repair the archive by WINRAR, then everything is OK and message is not reported any more. I assume that it's the wrong CRC.
Here is my code:
  lo_zip->get(
    EXPORTING  name                    = lc_shared_strings
    IMPORTING  content                 = l_xstr ). 
*... change content of L_XSTR, get new L_NEW_SHARED_STRINGS_XSTR
  lo_zip->delete( name = lc_shared_strings ).
  lo_zip->add( name    = lc_shared_strings
               content = l_new_shared_strings_xstr ).
* get ZIP content as XSTRING
  l_xstr = lo_zip->save( ).
* save ZIP file to PC
  CLEAR gt_upload.
  CALL FUNCTION 'SCMS_XSTRING_TO_BINARY'
    EXPORTING
      buffer     = l_xstr
    TABLES
      binary_tab = gt_upload.
  cl_gui_frontend_services=>gui_download(
           EXPORTING  filename   = p_file
                      filetype   = 'BIN'
*           IMPORTING  filelength = g_len
           CHANGING   data_tab   = gt_upload
           EXCEPTIONS OTHERS     = 19 ).
I also tried another approach: take what I needed from the original ZIP and re-pack it into another:
  lo_zip->delete( name = lc_shared_strings ).
  l_xstr_old = lo_zip->save( ).
  lt_splice = lo_zip->splice( l_xstr_old ).
  CREATE OBJECT lo_new_zip.
  LOOP AT lt_splice ASSIGNING <ls_splice>.
    lo_zip->get( EXPORTING name    = <ls_splice>-name
                  IMPORTING content = l_xstr_old ).
    lo_new_zip->add( name    = <ls_splice>-name
                     content = l_xstr_old ).
  ENDLOOP.
  lo_new_zip->add( name    = lc_shared_strings
                   content = l_shared_strings_xstr ).
  l_xstr = lo_new_zip->save( ).
*... save file to PC
The result was the same.
There is also a method CL_ABAP_ZIP=>CRC32 which returns integer CRC for given XSTRING, but I don't know how what to do with it (if anything).
I also found the following fourm posts claiming that the CRC is taken care of by CL_ABAP_ZIP:
1. [abap gzip zip|abap gzip zip;
2. [zip binary data and save zip file to disk at bsp|zip binary data and save zip file to disk at bsp;
3. [How to Zip the data in an internal table|How to Zip the data in an internal table;
They all suggest that it's as simple as my example above, but still, there's something wrong with my solution.
What could be wrong with my ZIP?
Thanks!
KR,
Igor

Answer 1

Solved: This unspecified "*... save file to PC" part of the code was wrong - I was saving a BIN file without filesize parameter supplied. The parameter was optional, but obviously important. Now it works perfect!