From:	Martin Str|mberg <ams AT ludd DOT luth DOT se>
Message-Id:	<199901040945.KAA29614@father.ludd.luth.se>
Subject:	Re: FAT32X and DJGPP
To:	eliz AT is DOT elta DOT co DOT il (Eli Zaretskii)
Date:	Mon, 4 Jan 1999 10:45:58 +0100 (MET)
Cc:	djgpp-workers AT delorie DOT com (DJGPP-WORKERS)
In-Reply-To:	<Pine.SUN.3.91.990103184216.13506B-100000@is> from Eli Zaretskii at "Jan 3, 99 06:48:34 pm"
X-Mailer:	ELM [version 2.4ME+ PL15 (25)]
MIME-Version:	1.0
Reply-To:	djgpp-workers AT delorie DOT com

According to Eli Zaretskii:
> > I'm mainly thinking of what would happen if somebody
> > reformats their D: drive to another FAT system, while a DJGPP program
> > is running.
> 
> Can Windows itself survive such an atrocity?  I would guess not.  It 
> should be the same as disabling long file names (which requires to 
> reboot).

You did see that said D:? At least DOZE do that (for example after
fdisking and the reboot, you format the drive and you don't need to
reboot again).

> > The X in FAT32X (cf. Subject)? Is that relevant?
> 
> I don't know.  Where did it come from?  Did I somehow mistyped the 
> subject?  If so, it's not relevant.

There's something called FAT32X, see
<http://www.compuclinic.com/osr2faq/index.html#fat32x>. Unfortunately
the link is broken.

Here's the result this far. The functions _get_fs_type() and
_get_fat_size() seems to me to be generally useful. But where in the
libc directories do they belong?

Additionaly, is there a template for libc's .txh files?


Right,

							MartinS


No hick-ups in my computer this time; although I can't guarantee yours.
----- start -----
#include <go32.h>
#include <dpmi.h>
#include <stdio.h>

int /* 0 == error; 1 == result_str filled in. */
_get_fs_type(const int drive /* drive number (1=A:). */
           , char *const result_str  /* String to put result in. At
least 9 char
s long. */
             )
{
  int n;
  __dpmi_regs r;

  /* Check DOZE version and return -1 if too low. */
  if( ( _get_dos_version(1) >> 8) < 4 )
  {
    return( 0 );
  }

  /* Call INT21, ax==0x6900 i.e. Get Disk Serial Number (sic!). */
  r.x.ax = 0x6900;
  r.h.bl = drive;
  r.h.bh = 0;
  r.x.ds = __tb >> 4;
  r.x.dx = __tb & 0x0f;
  __dpmi_int(0x21, &r);
  if( (r.x.flags & 1) == 0 )
  {
    /* Get the file system type. */
    for(n = 0; n < 8; n++)
    {
      result_str[n] = _farpeekb( _dos_ds, __tb + 0x11 + n);
    }
    result_str[8] = 0;

    return( 1 );
  }

  return( 0 );

}


int /* Number of bits in FAT; 0 == not FAT; -1 == error. */
_get_fat_size(const int drive /* drive number (1=A:). */
              )
{
  char s[9];
  int n;

  if( _get_fs_type( drive, s ) )
  {
    if( sscanf(s, " FAT%d", &n) == 1 )
    {
      return( n );
    }
    else
    {
      return( 0 );
    }
  }

  return( -1 );
}


int main(void)
{
  int ret;
  int i;

  for(i = 3; i < 20; i++)
  {
    ret = _get_fat_size(i);
    printf("%c: -> %d.\n", 'A' - 1 + i, ret);
  }

  return(0);
}
----- end -----

- Raw text -