@node _dos_getdiskfree, dos
@findex _dos_getdiskfree
@tindex diskfree_t@r{ structure}
@subheading Syntax

@example
#include <dos.h>

unsigned int _dos_getdiskfree(unsigned int drive, 
                              struct diskfree_t *diskspace);
@end example

@subheading Description

This function determines the free space on @var{drive} drive
(0=default, 1=A:, 2=B:, etc.) and fills @var{diskspace} structure.
The members of @code{struct diskfree_t} are defined by @code{<dos.h>} as
follows:

@example
struct diskfree_t @{
  unsigned short total_clusters;
  unsigned short avail_clusters;
  unsigned short sectors_per_cluster;
  unsigned short bytes_per_sector;
@};
@end example

@subheading Return Value

Returns with 0 if successful, non-zero on error (and sets @code{errno}
to @code{EINVAL}).

@subheading Portability

@portability !ansi, !posix

@subheading Example

@example
struct diskfree_t df;
unsigned long freebytes;

if ( !_dos_getdiskfree(0, &df) )
@{
  freebytes = (unsigned long)df.avail_clusters *
              (unsigned long)df.bytes_per_sector *
              (unsigned long)df.sectors_per_cluster;
  printf("There is %lu free bytes on the current drive.\n", freebytes);
@}
else
  printf("Unable to get free disk space.\n");
@end example