TPUG - Toronto PET Users Group/TPUG Users Group CD/TPUG Users Group CD.iso/AMIGA/(A)TA/(A)TAP.ADF/DS.readme

Text File | 1987-02-03 | 16KB | 347 lines

                        D i s k S a l v

                 AmigaDOS Disk Salvage Program

                 Copyright 1988 by Dave Haynie

                  Version 1.2 for AmigaOS 1.3


INTRODUCTION

    DiskSalv V1.2 is a disk recovery program for all Amiga file
system devices that use either the AmigaOS V1.2/V1.3 Standard File
System or the AmigaOS V1.3 Fast File System.  DiskSalv will scan a bad
disk volume for anything that can be recovered, and will restore these
items to any AmigaDOS volume.  It does not make any attempt to fix the
bad device in place; thus, any file that can't be restored with DiskSalv
might possibly be restored with an alternate method.


1. THE BASICS OF DISKSALV V1.2

    DiskSalv V1.2 (from here on referred to as "DiskSalv") is a
program designed to "salvage" any files and directories from a damaged
AmigaDOS file system device to a good one.  DiskSalv is run from an
Amiga CLI, and in the simplest case is used very much like the AmigaDOS
"DiskCopy" program.  For example, to recover files from a bad disk in
DF0: and restore them on a good disk DF1:, the user will type:

    1> DiskSalv FROM DF0: TO DF1:

Here the "FROM" and "TO" keywords are fully optional if the ordering of
the input and output devices is kept INPUT OUTPUT.  The following line
would also achieve the same result:

    1> DiskSalv TO DF1: FROM DF0:

In either case, DiskSalv will immediately print to the shell's screen:

    DiskSalv V1.2 Copyright ⌐ 1988 by Dave Haynie

    Salvage FROM Device DF0: TO Path DF1:

      DEVICE     =    trackdisk.device   (DF0:)
      UNIT       =        0    FLAGS      =        0
      HEADS      =        2    SECTORS    =       11
      LOCYL      =        0    HICYL      =       79
          LOBLOCK    =        0    HIBLOCK    =     1759
      RESERVED   =        2    MEMTYPE    =        3
      ROOT BLOCK =      880    DISK SIZE  =     1760

    Scan Range: START 2, STOP 1759, Expecting Standard FileSystem

    Should I continue [Y]

At this point, a simple RETURN entered will start up the recovery
process, while an "N" followed by a RETURN will abort the recovery.

1.1 The Scan Phase

    If we proceed with the recovery, DiskSalv will start the first
phase of it's recovery.  At this point, the input device will be scanned
from start to finish (blocks 2 though 1759).  DiskSalv is looking for
valid AmigaDOS file or directory blocks.  A small Intuition window
called "DiskSalv Scan" will open on the Amiga's WorkBench screen.  There
are three columns in this window, BLOCK, NODES, and TYPE.  As each block
is read, it's number is displayed under BLOCK.  This happens pretty
quickly; ordinarily, there's no need to examine individual block numbers
anyway.  The TYPE field indicates whether the block is a file (FILE),
root directory (ROOT), user directory (UDIR), data block (DATA), unused
block (FREE), unknown block type (????), or bad block (ERR!).  Note that
under the new AmigaDOS V1.3 Fast FileSystem, there's no way to
distinguish between DATA and FREE blocks during a scan, so these are
always displayed as unknown blocks.  The final field, NODES, indicates
the number of user directory or file blocks that have been located so
far.

    The other feature of this phase is the file list, which takes
place on the screen.  The shell window will indicate "Building Directory
Map...", and the name of each directory and file that's found will be
displayed under this heading.  Note that at any time during this
scanning phase, a ^C typed to the shell window will abort DiskSalv.

1.2 The Directory Resolution Phase

    The next phase is usually a very short one.  The scanning window
will disappear, and the shell window will indicate that DiskSalv is
"Resolving Stray Directories...".  During the scanning phase, when
DiskSalv finds a file block, it attaches it to a directory in it's
directory list.  To make the scan phase fast, however, DiskSalv only
does a single linear pass over the input disk during that phase.  If the
parent directory for a file or subdirectory isn't available, DiskSalv
makes a dummy directory for it in it's directory list.

    Normally, all of those dummy directories get changed into normal
ones as they are found in the scan.  However, there are some DiskSalv
modes (covered later) that may result in only a partial scan being
performed.  In this case, valid directory entires may be outside of the
scanning range.  In order to get the proper names of such directories,
the resolution phase goes through the directory entires in it's dummy
list and tries to find real directories to match them.  If a directory
can't be found, it was probably located on a bad block.  That's no
problem, all that's lost is the name of that directory, not any of it's
contents.

1.3 The Directory Pruning Phase

    The next pass happens purely in memory, and it attempts to
remove any empty directories from the directory list.  There are rarely
any empty directories that need to be restored, and there are some
DiskSalv options that tend to force a number of empty directories to be
created in the directory list.  This pass can be overridden if empty
directories are deemed important.

1.4 The Disk Salvage Phase

    In this next phase, the disk structure is actually restored to
the output device.  This proceeds until stopped via ^C, or until the
output device is full.  If the output device fills up, a new one can be
inserted if the device supports removable media.  The most common form
of this would be floppy disk.

    There are certain output devices which may not return proper
volume sizing information through AmigaDOS.  For instance, the RAM:
device always says it's full.  A DiskSalv option allows output size
checking to be turned off, and it's automatically selected if the
output device is RAM:.

    DiskSalv uses normal AmigaDOS I/O routines to re-create the
recovered files.  Thus, it may restore to a subdirectory instead of the
root of a device.  If a subdirectory is specified that doesn't exit,
DiskSalv will create it.  Similarly, DiskSalv may output to a logical
volume name instead of a device name.

    Finally, there are occasions under which there may be file name
collisions.  If the output device has a file by the same name as one
that's on the input device, such a collision occurs.  DiskSalv won't
overwrite files.  Instead, the colliding file is renamed before it is
rebuilt.  An extension is added to it, starting at "-0" and going on up
to "-100" as collisions continue to occur.


2. DISKSALV REFERENCE GUIDE

    The DiskSalv program is run and controlled completely via
command-line arguments.  It should run without problem from all Amiga
shell programs; it currently can't be run from the WorkBench.

2.1 Command-Line Options

    There are quite a few options in DiskSalv that'll modify in
various ways the recovery action described above.  The syntax for the
DiskSalv command line is given as:

    DiskSalv [FROM] InDev: [TO] OutPath [FFS|NOFFS]
             [ASK] [NOPRUNE] [NOCHECK] [NOTD] [QUICK]
             [START block|ROOT] [STOP [+]block]
             [MASK [a|A][r|R][w|W][e|E][d|D][p|P][s|S]]

    or

    DiskSalv HELP|INFO

The first form actually runs the program; the second form gives the user
a little built-in documentation.  In each case, text in brackets ("[]")
indicates an optional parameter, text outside of brackets indicates a
required parameter, and "|" indicates a choice of parameters.  The
options are:

ASK
    This options allows the Disk Salvage pass to proceed
    interactively instead of automatically.  The user is prompted
    at each file or directory.  A reply of 'Y' will recover that
    file or move into that directory, a reply of 'N' will skip that
    item.  Replying '?' will list all the valid options.  A reply of
    'A' will recover everything left at the current directory level;
    a reply of 'U' will skip everything left at the current
    directory level.  Finally, a reply of 'Q' will quit the program
    completely.

FFS | NOFFS
    This allows the disk's filesystem to be selected.  Normally,
    DiskSalv can tell the difference between a fast and standard
    filesystem disk, and will act accordingly.  However, if that
    disk is badly damaged, this assumption may be incorrect.  In
    such a case, DiskSalv will usually assume standard filesystem.
    If it's assumption is wrong, the filesystem can be forced with
    these options.

FROM InDev:
    This option allows an input device to be specified.  The input
    device must be a real device, not a path specification.  The
    FROM keyword is optional, but can be used to allow FROM and TO
    specifications to be given in any order.

HELP
    The HELP option lists some information about the various options
    available.  It should be specified in the command line without
    any other options.

INFO
    The INFO option lists some information about the program, it's
    distribution, bug reporting, and other stuff.  It should be
    specified in the command line without any other options.

MASK [a|A][r|R][w|W][e|E][d|D][p|P][s|S]
    This options allows the user to specify a protection bit mask as
    a filter.  The supported bits are "A" for Archive, "R" for Read,
    "W" for Write, "E" for Execute, "D" for Delete, "P for Pure, and
    "S" for Script.  Specifying the bit in lowercase indicates a mask
    for that bit not set, a bit in uppercase indicates a mask for that
    bit set.  For example, specifying "MASK a" will scan for only
    those files that don't have the archive bit set; "MASK WD" will
    scan only for those files with Write and Delete permission
    enabled.  Any bits not specifically MASKed can be in either state.

NOCHECK
    This option prevents the output device's size from being
    checked.  Normally this would only be used with a device that
    doesn't properly report it's size, and it's automatically
    invoked with output to RAM:.

NOPRUNE
    This option prevents the directory pruning phase from taking
    place.  If the input device contains empty directories that must
    be restored, use this option.

NOTD
    DiskSalv does some special optimizations when it's recovering from
    a floppy disk device based on the "trackdisk.device" driver.  While
    there's currently no real use for this option, a future version of
    "trackdisk.device" might possibly not work with these enhancements.
    This option will turn the enhancements off, making a recovery from
    the "trackdisk.device" work exactly like any other recovery.

QUICK
    This option performs a quick scan.  The scan speed is improved
    by not displaying the block number and type information for every
    block.  This doesn't make as much difference as it did in the
    earlier versions of DiskSalv; the "DiskSalv Scan" window routine
    has been greatly sped up this display.

TO OutPath
    This option allows an output path to be specified.  The output
    device can be any valid AmigaDOS file device specification.  The
    TO keyword is optional, but can be used to allow FROM and TO
    specifications to be given in any order.

START block | ROOT
    This option allows the scanning routine to start at any place on
    the input device.  This position is either given as a decimal
    block number, or as the string ROOT.  Since many files are
    clustered after the directory root on most disks, it's often
    possible to get many of a disk's files back starting the scan
    there instead of at the start of the disk.

STOP [+] block
    This option allows the scanning routine to stop at any place on
    the input device.  This position is either given as a decimal
    block number, or (via the optional "+") as an offset relative to
    the START of the disk.  Thus, specifying START ROOT STOP +50
    would scan a disk's root and the next 49 blocks.

2.2 Input Device Specification

    DiskSalv requires a DOS name specification for its input device.
Such a name is automatically created by the operating system for each
3.5" disk drive attached, and for some hardware add-ons during automatic
device binding process initiated by the AmigaDOS BindDrivers command.
Other DOS names are created by the Mount command and the MountList file.

    On occasion, a few problems show up in this theory.  First of all,
a device like a hard disk may store its physical layout, necessary to
create a DOS node, on the disk itself.  If the disk is damaged, this
special information may not be available any longer, and as a result, the
hard disk's device driver won't be able to create a DOS node.  In this
case, the user will have to create a MountList entry by hand for the
device.  This device will then be Mount-ed, and DiskSalv can take over
from there.

    The other problem I've found is that allowing AmigaDOS to access
a bad volume can occasionally result in a system crash.  With a mounted
volume, that's no big problem; AmigaDOS won't try to access the
device, or even load the device driver, until that drive is actually
accessed.  It's OK, and in fact required by DiskSalv, to just "Mount"
the device.  With floppies, this is a bit harder.  The trackdisk.device
looks for a diskchange signal from all 3.5" floppies, whenever a floppy
is changed.  So as soon as you insert a floppy disk, DOS will look at it.
If that disk causes a crash, it'll take effect as soon as the disk is
inserted.  Fortunately, there's a cure for this.  You can run DiskSalv,
giving it the proper device input, without the floppy actually in the
device.  Once DiskSalv starts up (at the "Should I Continue [Y]" prompt),
it inhibits that drive.  The dangerous floppy can then be inserted
without any problems.


3. LISCENCING AND DISTRIBUTION

    This program may be distributed free of charge, provided that no
extra restrictions are placed on it.  Nominal charges for copying or
on-line services are permitted provided that they are only for those
services.  This program was written to help out the Amiga community, not
to make folks feel guilty.  Thus, no payment is required for its use.

    I certainly don't mind donations, including donations of bug
reports, comments, suggestions for future enhancements, macadamia nuts,
or even software.  BUT PLEASE, DON'T SEND ME ANY PIRATED SOFTWARE.  YOU
WILL REGRET IT.  I wouldn't have thought it necessary to mention this,
given the quality of the people working with the Amiga (intelligent folks
recognize superiority).  But I received several such disks from users of
DiskSalv V1.0.  They all came from out of the country, and served me just
fine as blank disks.  But it really annoys me to see this.  Anyway, I can
be reached at:

                Dave Haynie
        645 Allen Avenue
        Gibbstown, NJ 08027

        BIX:    hazy
        PLINK:    D-DAVE H
        USENET:    ...!cbmvax!daveh

If you really want to send money, consider sending a donation instead to:

        GreenPeace
        1436 U Street NW
        Washington, DC 20009

Tell me about it, and I'll include you in my registration files.  I know
you don't get rich from "ShareWare"; while I got some donations from
DiskSalv V1.0 (which I'm certainly very grateful for), they certainly
didn't pay for the writing of DiskSalv V1.2.  I wrote DiskSalv V1.2
because it's needed, because I like to write programs in my spare time,
and for my ego -- if I didn't write DiskSalv V1.2, someone else out
there is going to write a better disk recovery program, and then mine
won't be the best any more.  Don't know if DiskSalv V1.2 necessarily is
the best these days, but I know it's better than DiskSalv V1.0.  Anyway,
while DiskSalv's saving your disks, maybe the folks at GreenPeace will
get a little extra money to save a few more important things, like clean
air, clean water, and wildlife.


                -Dave Haynie
                 September 14, 1988