The first example displays the volume label associated with a particular drive. The second example provides allocation information for a drive from the file system.

 #define INCL_DOSFILEMGR   /* File manager values  */
 #define INCL_DOSERRORS    /* DOS error values     */
 #include <os2.h>
 #include <stdio.h>

 int main(VOID) {

 ULONG       ulDriveNumber = 0;          /* Drive number */
 FSINFO      fsBuffer      = {0};        /* File system info buffer */
 APIRET      rc            = NO_ERROR;   /* Return code */

    ulDriveNumber = 3;          /* Specify drive C (A=1, B=2, C=3, ...) */

    rc = DosQueryFSInfo(ulDriveNumber,
                        FSIL_VOLSER,      /* Request volume information */
                        &fsBuffer,        /* Buffer for information     */
                        sizeof(FSINFO));     /* Size of buffer          */

    if (rc != NO_ERROR) {
        printf("DosQueryFSInfo error: return code = %u\n", rc);
        return 1;
    } else {
        printf("Volume label: '%s'\n", fsBuffer.vol.szVolLabel);
    }
    return NO_ERROR;
  }

#define INCL_DOSFILEMGR   /* File Manager values */
#define INCL_DOSERRORS    /* DOS Error values    */
#include <os2.h>
#include <stdio.h>

int main (VOID) {
   FSALLOCATE fsaBuffer     = {0};         /* File system info buffer     */
   APIRET  rc               = NO_ERROR;    /* Return code                 */

   rc = DosQueryFSInfo(3L,                     /* Drive number 3 (C:)     */
                       FSIL_ALLOC,             /* Level 1 allocation info */
                       (PVOID)&fsaBuffer,      /* Buffer                  */
                       sizeof(FSALLOCATE));    /* Size of buffer          */

   if (rc != NO_ERROR) {
      printf("DosQueryFSInfo error: return code = %u\n", rc);
      return 1;
   } else {
      printf ("%12ld bytes in each allocation unit.\n",
               fsaBuffer.cSectorUnit * fsaBuffer.cbSector);
             /* (Sectors per allocation unit) * (Bytes per sector) */
      printf ("%12ld total allocation units.\n", fsaBuffer.cUnit);
      printf ("%12ld available allocation units on disk.\n", fsaBuffer.cUnitAvail);
   }
   DosExit(EXIT_THREAD,fsaBuffer.cUnitAvail);  /* Return available allocation units
                                             to the initiating process      */
   return NO_ERROR;
}