PRODUCT  :  Borland C++                           NUMBER  :  1034
  VERSION  :  3.1
       OS  :  DOS
     DATE  :  October 19, 1993                         PAGE  :  1/2

    TITLE  :  Listing Device Drivers under DOS




  //  This program walks the device driver chain, showing all the
  //  devices that are present.  To get the start of the chain, int
  //  21,52  (the undocumented 'Get List of Lists' function) is
  //  used.  For more information, see 'Undocumented DOS' by Andrew
  //  Schulman.

  #include <stdio.h>
  #include <string.h>
  #include <dos.h>
  #include <alloc.h>

  struct driver_hdr
  {
       struct driver_hdr far *  next;
       unsigned       device_attrib;
       unsigned       DSEP;
       unsigned       DIEP;
       char           devname[8];
         // If this is a block device, the first byte is the number
         //   of subunits (drives) supported by this driver.

       unsigned       reserved;      // (CD-ROM) must be 0000h
       char           drive_letter;  // (CD-ROM) initially 0.
       char           num_units;     // (CD-ROM)
       char           signature[6];  // (CD-ROM)
  };
  typedef struct driver_hdr driver_hdr;

  char blkdev[] = "Block: ";
  char blkcnt[] = "Unit(s)";

  unsigned i, j, k;
  driver_hdr far * dheader;
  char far * name;

  int devices(void)
  {
       name = (char far *)malloc(10);

       asm mov ah, 52h
       geninterrupt(0x21);
       asm add bx, 22h
       dheader = (driver_hdr far *)MK_FP(_ES, _BX);













  PRODUCT  :  Borland C++                           NUMBER  :  1034
  VERSION  :  3.1
       OS  :  DOS
     DATE  :  October 19, 1993                         PAGE  :  2/2

    TITLE  :  Listing Device Drivers under DOS.




       _fstrncpy(name, dheader->devname, 8);
       name[8] = 0;
       printf("%Fp     %s\n", dheader, name);
       while(FP_OFF(dheader) != 0xffff)
       {
            i = dheader->device_attrib;
            if ((i && 0x8000) != 0)
                 printf("%Fp     %s\n", dheader, name);
            else
                 printf("%Fp     Block: %u Unit(s)\n", dheader,
                       (unsigned)dheader->devname[0]);
            dheader = dheader->next;
            _fstrncpy(name, dheader->devname, 8);
            name[8] = 0;
       }
       return 0;
  }


  int main( void )
  {
       devices();
       return 0;
  }


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