Amiga Computing 67/ac067a.adf/Utilities/FixDisk.doc

Text File | 1978-03-30 | 12KB | 264 lines

                  FixDisk V1.2
           (C) Copyright Werner Guenther 1990
                Freeware
            USE THIS PROGRAM AT YOUR OWN RISK


  FixDisk is a program to recover as much as possible from a defective disk.
  I don't claim it is better than Diskdoctor or DiskSalv, but it has some
features the others don't have:
  It can recover damaged (unreadable) tracks. It has functions to check
file integrity, to check the directory structure and functions to undelete,
copy or show (even defective) files and fix corrupted directory pointers.
  A damaged file structure can be recovered copying the data file by file
to another disk (a la DiskSalv) or can be fixed in place (like Diskdoctor).
  Everything can be selected with an intuition interface, so users can
determine what action should be take place.
  Now the bad news: The program does not keep track of loose blocks, those
files without a file header, as DiskSalv does.
  It doesn't process partitions > 48Mb.

USAGE

  After starting FixDisk from CLI or Workbench, you will see a set of
gadgets with the available drives on the top of the window. Choose the
desired drive by clicking its gadget. If the chosen drive is a 3.5" or a
5.25" drive, you will be asked to insert a disk. Now the program starts to
read in the disk, cylinder by cylinder, searching for file/directory
headers. This may take a while, so be patient.
  You may be told of read errors and other messages at this point:
  - Block 0 has to start with `DOS' or `KICK'. If it does not, you are
asked if you want to fix it.
  - The program couldn't find the root block and FixDisk wants to build a
new one.
  - The disk isn't validated and the program will validate it.
  - There is no root block and no file header on the disk, meaning the
disk is probably a custom disk or the Kickstart disk. FixDisk won't check
anything and won't let you check, change or fix anything except read errors.
   You may press break (CTRL-C) if you want to abort this operation. When
the disk has been examined, you'll get a file requester on the left half of
the window. The first column shows the key, the block number where the file
header has been found, followed by DEL for deleted files or '-->' followed
by the file name. Red (color 3) entries are directories. Click on the
file name to select it or shift-click for multiple selections. Double-click
a directory to enter the directory.
  The right half of the window is filled with 17 gadgets. Some of them are
disabled at startup. These gadgets will write onto the disk. To enable them,
choose "Write enable" from the Miscellaneous menu.

THE GADGETS:

Scan mode - ALL
    Tells FixDisk to read the entire disk, cylinder by cylinder. This is
    the safest way of operation and makes sure you get any fileheader on
    the disk. It is used if the disk is heavily damaged, or if you want
    to undelete/recover all deleted files.

Scan mode - Directory
    This is much faster than the previous one. It builds up the disk
    structure by following the hash chains, i.e. by reading the directory.
    Use this one for smaller problems like a 'key already set' error.

Scan mode - Deleted
    Similar to 'Scan mode - All' but somewhat optimised to find
    fileheaders. You may enter a filename to search for, if you wish.

Scan mode - Specify
    Used to find deleted files. Lets you specify which cylinders to scan,
    in case you already know where the fileheader was. The usual trick is
    to type 'list keys' and to look where other files with the same date
    are stored and to scan the cylinders in the vicinity.

Directory - Parent
   This gadget is part of the file requester. The requester will show files
   from the parent directory.

Directory - Root
  Same as above, but steps to the root directory.

Show - Selected
  Shows a file in Hex or ASCII. Like all other commands, the file is
  processed without using DOS, but each sector (block) is read, checked and
  displayed. It works just as "Copy" does (see below), so you can use this
  function to see what exactly can be recovered from a defective file. If
  the file is on a 'Standard Filesystem' (non FFS) disk, you will be asked
  from where the program should take the file links. Each block that
  belongs to a file is listed in the file header block and in one or more
  "file list blocks" if the file is too large. On the "Standard Filesystem,"
  each data block has a pointer to the next block belonging to the same file.
  So there are two ways to determine how the file is built: using the links
  listed in the file header, or using the inter-block links. It is much safer
  if you select the file header links, since if only one block is wrong,
  you'll get rubbish using the inter-block links.

Check Files - Selected
  This function checks the selected files. With the standard filesystem it
  is easy to determine if a file is good or defective, as each data block
  has a checksum, a pointer to the file header, pointer to the next block,
  etc. This is not the case with the FFS and there is no way to determine
  if a given data block really belongs to that file. So even if the file
  passes the test, it may still be corrupt.

Check Files - Deleted Checks
  only deleted files, so you can see which one can be undeleted.

Check Files - All
  Checks all files.

Undelete Files - Selected
  This function first calls "check file." If the file seems to be OK, the
  file header is inserted into the hash chain of its parent directory and
  the bitmap is updated, but the "Bitmap Flag" changes to FALSE, just to
  make sure the disk is validated after this operation.

Undelete Files - All
  Tries to undelete all deleted files.

Copy Files - Selected
  Works like "Show" (see above). You'll be asked to enter an output
  path/directory. If the directory fills, you may enter a new path. If a
  given file already exists in the destination directory, the program will
  append ".2" to the filename (if .2 exists too, you'll get .2.2. (Don't
  tell me this is dumb, I know that already.) As with "Check File," you may
  get some error messages while the program is working. If a block doesn't
  seem to belong to a given file, you'll be asked to "SKIP IGNORE ABORT."
  Skip means the damaged block won't be copied, Ignore the block will be
  copied, no matter what is on that block, Abort leaves "Copy Files."
  Protection bits are preserved, dates are not.

Copy Files - All
  Copies the entire disk, trying to recover as much as possible.

Wipe Files - Selected
  This function clears the file header of a deleted file. Utilities like
  Diskdoctor and DiskSalv will try to recover all files, even if they have
  been deleted. If you don't want some files to pop up again using one of
  the programs above, you may use this function. Be warned: After this
  operation you'll have to use a disk-monitor/sector-editor to get the data
  back.

Wipe Files - Deleted
  Purges all deleted files.

Delete - Selected
  Deletes a file, i.e. the file header will be taken out of its hash chain,
  and the bitmap updated. The 'Bitmap Flag' will be set to FALSE as in
  "Undelete" (see above). This function even works if the DOS delete does
  return an error.

Delete - Faulty
  Checks all files and deletes those with errors. The program may ask you
  before deleting a file, if you wish.

Info - Device
  Returns some information about the selected device.

Validate - Disk
  This is not the Amiga validator but my own. The main difference between
  them is that this one tries to repair the disk structure. You may get
  some error reports: loops in a hash chain, wrong or unreadable file
  headers, checksum errors or "key already set," two files claiming to own
  the same data block. You will be informed about any error and prompted
  before FixDisk attempts to fix it.

Rename - Selected
  Rename a selected file.

Recover - Track
  Tries to recover tracks with read/write errors on floppy disks. It uses
  the RAWREAD command from the trackdisk.device and therefore works with
  the trackdisk.device only. It will RAWREAD the track into a buffer,
  search the syncs and decode the sectors. If a sector sync is missing, the
  program tries to determine where the sector has to start. When the track
  has been decoded, you'll get a window displaying: the number of the
  sector (1-11), the first four longwords of that sector, if the checksum
  is OK or BAD, and if that block is ALLOCated or FREE. If an entries is
  red (color 3), the sector didn't have a sync. If instead of the first few
  bytes you get "unreadable," the program couldn't even work out where the
  sector should have been. If you are not satisfied with the result, you
  may click RETRY to restart the procedure and usually get a different
  result. If you think the result is good enough, click on WRITE. This will
  format the track and write those sectors back. If the track has a hard
  error, i.e. a damaged surface, it may happen that the track can't be
  formatted. Click RETRY several times and the defective part of the track
  may fall into the gap at some point. If this doesn't seem to work, select
  SAVE from the requester and save the track to a file. Now exit FixDisk,
  backup the disk and restart FixDisk using the backup. Select
  Recover-Track and click LOAD from the requester, filling the buffer with
  the data from the original disk. After selecting WRITE again, the track
  should be recovered.

  Gadgets on the "Recover - Track" requester:

      RETRY
    read and decode the same track again.

      WRITE
    reformat the track an write the data back to the disk.

      NEXT / NEW
    FixDisk builds a list of unreadable tracks. "NEXT" steps to the
    next damaged track on the list. If the list is empty, the gadget
    will display "NEW" instead.

      FIND
    Searches a pattern anywhere in the buffer. Useful if you know the
    first few bytes of a sector (which is quite easy to determine on a
    standard file system disk).

      SAVE
    Save the decoded track to a file.

      LOAD
    Read a decoded track from a file into the buffer.

      CANCEL
    Quit 'Recover - Track' and return to FixDisk's main window.

  The window displaying the sectors has several gadgets too:

      LEFT ARROW
    If a sector sync mark is missing, FixDisk will compute the position
    of that sector within the buffer and decode the sector from this
    point. You may manually correct this position using the arrow
    gadgets. The left arrow will shift the starting position one BIT
    (not byte) to the left.

      RIGHT ARROW
    Shift sector one bit to the right.

      NUMERIC STRING GADGET
    the string gadget will display the position of the sector relative
    FixDisk assumption.

      SECTOR DATA
    clicking onto the sector data area will 'lock' the sector, i.e.
    will prevent FixDisk from redecoding this sector when using
    RETRY from the requester.

THE MENU
  There are actually only two menu items:

Ignore Readerrors
  Usually you get a requester asking RETRY IGNORE if an error occurs. This
  may be annoying if the disk has many defective tracks. This item will
  stop that requester popping up. It has also a second function. If you are
  using the "Copy" function, the program will stop every time a file seems
  to be damaged and ask what action should be taken. With "Ignore
  readerrors" on, errors are just listed, but the program will act as if
  you have chosen IGNORE.

Write Enable
  Enables those gadgets that will write onto the disk.

 That's all. Well, almost. The program has about 80 requesters, some of
them have not been explained, but they should be self-explanatory.

Send flames, bug reports, requests to
 [e-mail]

Werner Guenther
Wingertspfad 12
D 6900 Heidelberg (FRG)