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DMSDOS 0.9.1.5

DMSDOS ioctl commands (outdated.... newers are missing here)

*****************************************************************************
WARNING: INFORMATION IN THIS FILE IS OUTDATED AND PARTIALLY WRONG. SEE THE
         DMSDOS UTILITIES SOURCE CODE FOR PROGRAMMING EXAMPLES.

         When I have enough time I write better documentation.....
*****************************************************************************

Example code:

  #include<stdio.h>
  #include<linux/dmsdos_fs.h>
  #include<sys/ioctl.h>
  #include<sys/types.h>
  #include<sys/stat.h>
  #include<fcntl.h>
  #include<string.h>
  #include<errno.h>

  Dblsb dblsb;
  int fd;
  int ret;
  unsigned long w[10];
  Mdfat_entry mde;

  /* open file descriptor fd */
  fd=open(CVF_name,O_RDONLY);
  if(fd<0)
  { printf("No such file or directory.\n");
    return;
  }

DMSDOS_GET_DBLSB:
read DMSDOS version number and read CVF parameters in dblsb structure.
This function also performs a version check, i.e. if the dmsdos driver in
the kernel thinks the version number you supply in s_dcluster is too old, 
it "or"s the returned value with 0x0f000000 and doesn't fill in the values
for the dblsb structure.

** Since not all DMSDOS versions support all commands, this ioctl should be
always issued first **

  dblsb.s_dcluster=DMSDOS_VERSION;  
  ret=ioctl(fd,DMSDOS_GET_DBLSB,&dblsb);
  if(ret<0)
  { printf("This is not a DMSDOS directory.\n");
    exit(1);
  }
  printf("You are running DMSDOS Version %d.%d.%d.\n\n",(ret&0xff0000)>>16,
         (ret&0x00ff00)>>8,ret&0xff);
  if(ret&0x0f000000)
  { printf("This program is too old for the DMSDOS version you are running.\n");
    exit(1);
  }

  dblsb structure see dmsdos.h.

DMSDOS_READ_BITFAT:
read bitfat entry
w[0]=sectornr; returns 0 in w[1] if sector free

  ret=ioctl(fd,DMSDOS_READ_BITFAT,w);
  if(ret<0)error.....;

DMSDOS_WRITE_BITFAT:
write bitfat entry
w[0]=sectornr, w[1]=new value (0=free, 1=allocated)

  ret=ioctl(fd,DMSDOS_WRITE_BITFAT,w);
  if(ret<0)error.....;

DMSDOS_READ_MDFAT:
read mdfat entry
w[0]=clusternr; returns result in mde structure.

  w[1]=&mde;
  ret=ioctl(fd,DMSDOS_READ_MDFAT,w);
  if(ret<0)error......;
  
DMSDOS_WRITE_MDFAT:
write mdfat entry
w[0]=clusternr; mde=new mdfat entry value.
  
  w[1]=&mde;
  ret=ioctl(fd,DMSDOS_WRITE_MDFAT,w);
  if(ret<0)error......;

raw MDFAT entry: 32/40 bit number (hidden to the user)

  dos 6.x, Win95 without drivespace 3:
  3322222222221111111111
  10987654321098765432109876543210 
  ucaaaammmm?sssssssssssssssssssss

  Win95 with drivespace 3:
  33333333322222222221111111111
  9876543210987654321098765432109876543210 
  ucaaaaaammmmmm??ssssssssssssssssssssssss

Mdfat_entry structure: (the dmsdos driver automatically converts it to the
                        appropriate 32 or 40 bit number)

  mde.sector_minus_1= ('ssss...' bits)
  mde.size_lo_minus_1= ('mmmmmm' bits)
  mde.size_hi_minus_1= ('aaaaaa' bits)
  mde.flags= ('uc' bits)
  mde.unknown= ('?' bit(s)), are NOT written, always set to zero
  
  u: 1=entry is used, 0=entry is free
  c: 1=cluster is uncompressed, 0=cluster is compressed
  a: uncompressed size minus 1 (number of sectors belonging to this cluster)
  m: compressed size minus 1 (      "      "        "          )
  ?: unknown, but seem(s) to be used sometimes
  s: sector number minus 1 (theoretical 2 GB limit)
     The sector number is counted from the beginning of the CVF file
     starting with sector number 0.

DMSDOS_SET_COMP:
set compression method for write access.
  
  ioctl(fd,DMSDOS_SET_COMP,READ_ONLY); or:
  ioctl(fd,DMSDOS_SET_COMP,UNCOMPRESSED); or:
  ioctl(fd,DMSDOS_SET_COMP,GUESS); or:
  ioctl(fd,DMSDOS_SET_COMP,DS_0_0); or:
  ioctl(fd,DMSDOS_SET_COMP,DS_0_1); or:
  ioctl(fd,DMSDOS_SET_COMP,DS_0_2); or:
  ioctl(fd,DMSDOS_SET_COMP,JM_0_0); or:
  ioctl(fd,DMSDOS_SET_COMP,JM_0_1); or:
  ioctl(fd,DMSDOS_SET_COMP,SQ_0_0);

DMSDOS_SET_CF:
set compression level:
  
  ioctl(fd,DMSDOS_SET_CF,level-1);

DMSDOS_EXTRA_STATFS:
special statfs command for dmsdos
reads special info in w.

  ioctl(fd,DMSDOS_EXTRA_STATFS,w);

w[0]= free sectors in CVF.
w[1]= used sectors.
w[2]= maximum free unfragmented sectors (contiguous sectors)
w[3]= free fat clusters
w[4]= used fat clusters
w[5]= clusters allocated in fat but free in MDFAT (filesystem error if > 0)
w[6]= sum of sectors used by compressed clusters
w[7]= sum of sectors used by uncompressed clusters
w[8]= number of compressed clusters
w[9]= number of uncompressed clusters

DMSDOS_READ_BLOCK:
read sector from CVF; returns sector contents in bstruct.data;

  struct bstruct
  { unsigned long sectornr;
    unsigned char data[512];
  };

  bstruct.sectornr= sector number;

  ioctl(fd,DMSDOS_READ_BLOCK,&bstruct);

DMSDOS_WRITE_BLOCK:

  analogue to read_block...

DMSDOS_READ_DIRENTRY:
DMSDOS_WRITE_DIRENTRY:

  removed and unsupported...

DMSDOS_READ_DFAT:
w[0]=clusternr; returns fat entry value in w[1]; (last=-1 or 0xFFFFFFFF)

  ret=ioctl(fd,DMSDOS_READ_DFAT,w);
  if(ret<0)error......;

DMSDOS_WRITE_DFAT:
w[0]=clusternr; w[1]=new value;

  ret=ioctl(fd,DMSDOS_WRITE_DFAT,w);
  if(ret<0)error......;

DMSDOS_SIMPLE_CHECK:
performs simple filesystem check (crosslinks & allocation errors)
w[0]=0; means do not try to repair errors

returns result in w[0] (0=ok, -1=FAT error, -2=MDFAT error, -3=BITFAT error,
                        1=out of memory, check aborted,
                        2=FAT ok, but out of memory for MDFAT check)

  ioctl(fd,DMSDOS_SIMPLE_CHECK,w);
  if(w[0]==....)printf(.....);


dmsdos daemon ioctls missing here....

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