CREATE OR REPLACE LIBRARY nt_kernel AS
'C:\Windows\System32\kernel32.dll';

CREATE OR REPLACE PACKAGE disk_util
AS
   FUNCTION get_disk_free_space (
      root_path                  IN       VARCHAR2,
      sectors_per_cluster        OUT      PLS_INTEGER,
      bytes_per_sector           OUT      PLS_INTEGER,
      number_of_free_clusters    OUT      PLS_INTEGER,
      total_number_of_clusters   OUT      PLS_INTEGER
   )
      RETURN PLS_INTEGER;

   PRAGMA RESTRICT_REFERENCES (get_disk_free_space, WNPS, RNPS, WNDS, RNDS);
END disk_util;
/

CREATE OR REPLACE PACKAGE BODY disk_util
AS
   FUNCTION get_disk_free_space (
      root_path                  IN       VARCHAR2,
      sectors_per_cluster        OUT      PLS_INTEGER,
      bytes_per_sector           OUT      PLS_INTEGER,
      number_of_free_clusters    OUT      PLS_INTEGER,
      total_number_of_clusters   OUT      PLS_INTEGER
   )
      RETURN PLS_INTEGER
   IS
   EXTERNAL
      LIBRARY nt_kernel                   -- our library (defined previously)
      NAME "GetDiskFreeSpaceA"            -- name of function in kernel32.dll
      LANGUAGE c                          -- external routine is written in C
      CALLING STANDARD pascal             -- uses Pascal parameter convention
      PARAMETERS                    -- map PL/SQL to C parameters by position
                (
         root_path STRING,
         sectors_per_cluster BY REFERENCE LONG,
         bytes_per_sector BY REFERENCE LONG,
         number_of_free_clusters BY REFERENCE LONG,
         total_number_of_clusters BY REFERENCE LONG,
         RETURN LONG
      );                       -- "return code" indicating success or failure
END disk_util;
/

SET SERVEROUTPUT ON SIZE 100000          
DECLARE
   lroot_path                  VARCHAR2 (3) := 'C: ';      -- look at C drive
   lsectors_per_cluster        PLS_INTEGER;
   lbytes_per_sector           PLS_INTEGER;
   lnumber_of_free_clusters    PLS_INTEGER;
   ltotal_number_of_clusters   PLS_INTEGER;
   return_code                 PLS_INTEGER;
   free_meg                    REAL;
BEGIN
   /* Call the external procedure.  We ignore the return code in this simple example.*/
   return_code :=
      disk_util.get_disk_free_space (lroot_path,
                                     lsectors_per_cluster,
                                     lbytes_per_sector,
                                     lnumber_of_free_clusters,
                                     ltotal_number_of_clusters
                                    );
                  /* Using the drive statistics that are returned from the external procedure,
   ||compute the amount of free disk space.  Remember Megabytes = (Bytes / 1024 / 1024)
                */
   DBMS_OUTPUT.put_line ('lsectors_per_cluster = ' || lsectors_per_cluster);
   DBMS_OUTPUT.put_line ('lbytes_per_sector = ' || lbytes_per_sector);
   DBMS_OUTPUT.put_line (   'lnumber_of_free_clusters = '
                         || lnumber_of_free_clusters
                        );
   DBMS_OUTPUT.put_line (   'ltotal_number_of_clusters = '
                         || ltotal_number_of_clusters
                        );
   free_meg :=
        (lsectors_per_cluster * lbytes_per_sector)
      * (lnumber_of_free_clusters / 1024)
      / 1024;
   DBMS_OUTPUT.put_line ('free disk space, megabytes = ' || free_meg);
END;
/