Xref: news-dnh.mv.net comp.os.msdos.djgpp:4555
From: u7711501 AT bicmos DOT ee DOT nctu DOT edu DOT tw (Jih-Shin Ho)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Finding which drives exist
Date: 20 Jan 1996 06:15:06 GMT
Organization: Computer Center, National Chiao-Tung University, Taiwan
Lines: 53
Message-ID: <4dq19a$3u0@ccnews.nctu.edu.tw>
References: <DLFvGL DOT 8xJ AT jade DOT mv DOT net>
NNTP-Posting-Host: bicmos.ee.nctu.edu.tw
NNTP-Posting-User: u7711501
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

A.Appleyard (A DOT APPLEYARD AT fs2 DOT mt DOT umist DOT ac DOT uk) wrote:
: I wrote a big Gnu C++ program (an emacs-type text editor). I found today that
: various DOS interrupts that are supposed to make specific fault returns when I
: try to access a nonexistent drive, when Novell Netware is active act very odd
: and cause aborts in my program; and I have to run with Novell active most of
: the time. Luckily I have managed to cobble matters together so that a
: nonexistent drive looks to a user of my program like an empty drive that can't
: be written to. But this is unsatisfactory. Please how in Gnu C++ can I find
: easily at run time for(i='A';i<='Z';i++) whether drive i exists? And I don't
: want in the process any empty floppy or CD-ROM drives making rude noises at me
: or wanting Abort/Fail/Retry. I don't mind if an empty floppy drive is treated
: as nonexistent. It seems easy enough: the File Manager in Windows gets it
: right every time and displays across the top of its window a row of little
: disk drive icons, one for each existing logical drive.

The following code is for Turbo-C. You can convert it to DJGPP style easily.
It can detect physical drive and logical drive (for example, network drive).

/*
  Find all system disk drives, for Turbo-C

  Written by Jih-Shin Ho, 1995
*/

#include <stdio.h>
#include <stdlib.h>
#include <dos.h>

int main()
{
  union REGS regs;
  int i;

  printf("Disk drive found : ");
  for (i = 0; i < 26; ++i) {
    regs.x.ax = 0x4409; /* get drive flags */
    regs.h.bl = i + 1;  /* 1-based dos drive */
    intdos(&regs,&regs);
    if (!regs.x.cflag) printf("%c ",'A' + i);
  }
  printf("\n");
  return(0);
}

--
  Jih-Shin Ho, National Chiao Tung University
  u7711501 AT bicmos DOT ee DOT nctu DOT edu DOT tw

  DISPLAY -- universal image/movie viewer, converter, and indexer for DOS.
  Package name  : disp???a.zip, disp???b.zip. ??? is version number.
  Official site : NCTUCCCA.edu.tw:/PC/graphics/disp.
  Other site    : oak.oakland.edu:/SimTel/msdos/graphics.
  WWW page      : http://bicmos.ee.nctu.edu.tw/