xDMS - extracting DMS disk image files
--------------------------------------
Introduction:
-------------
Some time ago I started using UAE and Fellow Amiga emulators in the PC,
while still using my Amiga. Both emulators are very nice, and I started
testing some of my old games and demos with it. But a thing annoyed me. I
have some CDs with demos and other software, with hundreds of disk images
compressed with DMS. DMS was always the Amiga 'de facto' standard for
storing copies of non-dos disks, as used by most games and demos. But the
emulators required the Amiga software to be in uncompressed disk image
format (now known as .ADF) or disk images compressed with gzip (ADZ). To
use my DMS archives in the emulators I had to uncompress them with DMS
inside the emulation, saving it as an uncompressed disk image in the PC
hard disk. It was very boring, and also a waste of time and hard disk
space, since I could not leave the files into the CDs. I thought a much
better solution would be to add direct support for DMS files in the
emulators itselves, in the same way as they support gzip compressed images.
But as DMS uses a proprietary format, I thought DMS support in the near
future would be unlikely. So I decided to do something myself and began to
study the inner workings of DMS. After some days of hard work, I wrote a
portable DMS unpacker, xDMS. xDMS is more useful for users of Amiga
emulators, but can also be useful for actual Amiga users too.
xDMS Features:
--------------
Supports decompression of files compressed using all known DMS
compression modes, including old and obsolete ones, and also encrypted
files, for 100% compatibility.
Can test DMS files integrity, view file informations and show attached
Banners and FILEID.DIZ .
Can generate standard disk images and compressed disk images, using gzip,
if you want to store your files in ADF or ADZ formats.
Can extract the files contained inside the DMS archives, if the
compressed disk is an AmigaDOS disk, using readdisk made by Bernd Schmidt.
Can process multiple files in batch with a single command, and also use
stdin and stdout for input and output of data.
Installation:
------------
This archive contains xDMS in binary executable format for AmigaOS,
MS-DOS and Linux/Intel/ELF, and also its source code. If the system you
use is one of these, you can just copy the binary file to a directory in
your path. If you use another system, you will need to compile xDMS
yourself. xDMS was written in ANSI C and should work with most ANSI C or
C++ compilers and platforms with minor or no changes. It was tested under
Linux with GCC, MS-DOS with DJGPP and Amiga with SAS/C and worked well,
without warnings. To compile it with GCC or DJGPP you can just use make
with the supplied Makefile. For other compilers you may have to modify it
slightly. A smakefile for SAS/C is also supplied. After a successful
compilation you can install the generated executable somewhere in your
path. You also need to install gzip and readdisk if you want to be able to
create gzip compressed disk images and extract files from DMS. gzip is
available in most public domain software libraries. Readdisk is supplied
with UAE. You probably already have both.
Usage:
------
xDMS is a shell utility program. When executed without arguments, it
shows an usage screen. The template of xDMS is the following:
xdms [options] <command> {<dms_file[.dms]> [+output]}
Arguments inside [] are optional. Arguments inside <> are required.
Arguments inside {} can be used one or several times.
A command is indicated by a letter and can be one of the following:
t : Test DMS archives
u : Unpack DMS archives to disk images
z : Unpack to disk images and compress it with gzip
x : Extract files inside DMS archives using readdisk
v : View DMS archives information
f : View full information
d : Show attached FILEID.DIZ
b : Show attached Banner
If the supplied input DMS file name doesn't have a .DMS or .dms
extension, a default .dms will be appended to it.
The output argument is optional and specifies a file name or a directory
for each unpacked file. If the output filename is not supplied, it is
generated from the input filename. If the generated file is a standard
disk image it will have the .adf extension. If it is a compressed image
the extension will be .adz . If you supply an output file name, no
extension will be added. By default, files are unpacked to the current
directory, unless you specify another directory with the output file name
or use the -d option.
Commands z and x respectively need gzip and readdisk instaled in the
current path, or it will fail.
When extracting files with x option, xDMS will call readdisk and it will
reconstruct the tree of files and directories contained inside the DMS
compressed disk image, starting in a directory with the same name as the
volume name of the disk in the DMS file. This command can fail if xDMS
can't execute readdisk, or if the dms compressed disk is not an AmigaDOS
disk. The current version of readdisk supplied with UAE only supports old
OFS Kickstart 1.x compatible disks, reporting any of the newer formats
introduced with AmigaOS 2.0 or newer as non-dos disks, while they actualy
are.
The v commands show some information contained in DMS files, as the
version of DMS that created it, the type of the disk, date of creation,
number of tracks, etc. The f command also shows additional tracks
informations.
The b command shows the banner, if the file contains one. A banner is a
text that is displayed when DMS unpacks a file and usually contains
informations about the group/BBS/person that made it.
The f command shows the FILEID.DIZ, if found in the DMS. It is a text
that identifies what the DMS file contains.
You can also supply as input filename stdin and/or +stdout as output. in
this case xDMS will read the data from the standard input and/or send it to
the standard output.
You can supply multiple input and optional output files and use wild
cards. When using wildcards, the +output argument will affect only the
last file name expanded from the wildcard. To supply a global destination
directory you must use the -d option. All commands and options are not
case sensitive.
You can also supply one or more (or none) of the following options:
-f : Override errors (to salvage broken data tracks)
-q : Quiet
-v : Verbose
-d <destdir> : Set destination directory
-p <password> : Decrypt encrypted archives using password
When more than one option is supplied they must be separated. You can't
use something like -qd dir .
The quiet option suppresses all messages usually emited by xDMS,
including error messages. It is mostly to be used when xDMS is called from
inside emulators or some type of front-end. The program that calls xDMS
can verify if the operation was successful checking the return code of
xDMS. It will be zero if the operation was successful or non-zero if it
failed for one or more files.
The verbose option makes xDMS display more messages than it usually does,
including a progress indicator when unpacking files. This indicator is
only useful if you have a slow computer.
The -d option specifies a global destination directory. This directory
name is inserted before the name of any output file or output directory
supplied with +output in the command line.
The -p option uses a password to decrypt the dms files if they are
encrypted. DMS uses a very lame encryption algorithm that could be easyly
cracked. In fact, if the file is encrypted, and contains a banner, you can
unpack it with any password.
Some examples:
xdms u foo.dms
This will unpack the file foo.dms in the current directory and save it as
foo.adf, also in the current directory.
xdms -v -d /tmp/tst u foo +bar.dsk
This will unpack the file foo.dms in the current directory and save it as
/tmp/tst/bar.dsk . Aditional messages and a progress indicator will be
displayed.
xdms f ram:Hardwired1.dms (in the Amiga or inside Amiga emu)
This will show informations about the file Hardwired1.dms in Amiga's Ram
Disk, including tracks information.
xdms -p treva u tst1 tst2 +tstdir/ttt tst3.DMS +stdout >tora
This will (try to) unpack the files tst1.dms, tst2.dms and tst3.DMS in the
current directory. If any of them is encrypted xDMS will try to decrypt it
using the password "treva". tst1.dms will be unpacked as tst1.adf,
tst2.dms as tstdir/ttt and tst3.DMS will be unpacked to stdout that is
redirected to file tora.
xdms -d /home/apele/uae/demos z /mnt/cdrom/*.dms (under Linux)
xdms -d c:emulfellowdemos z f:*.dms (under MS-DOS)
This will unpack all files with the dms extension in the root directory of
a CDROM disk, pack it again using gzip and save it in another directory.
The generated files will have the .adz extension.
xdms -q x tst
This will (try to) extract the files contained inside the tst.dms file.
The files and directories will be extracted to a directory with a name
equal to the volume name of the disk contained in the dms file. No
messages will be displayed.
xdms -d stdout u *.dms >bigfile
This will unpack all the dms files in the current directory and save them
all to a single file.
xdms -d /home u apele +apele/yourfile.adf trevor +trevor/yourfile.adf
This will unpack the file apele.dms in the current directory and save it as
/home/apele/yourfile.adf . Will also unpack the file trevor.dms as
/home/trevor/yourfile.adf .
cat tst.dms | xdms u stdin +stdout | strings | more
This will display the ascii strings inside the unpacked dms file. In this
case, xDMS is used as a filter.
Known problems:
---------------
If you try to extract the files (using the x command) of a DMS archive
that contains a disk in one of the disk formats introduced with AmigaOS
version 2 or newer, it will fail. Also, if you try to extract the files
under MS-DOS it will almost always fail. It's not a problem in xDMS. It
is a problem in the current version of readdisk. It only suports OFS
disks. Another problem of readdisk is that it fails when executed under
MS-DOS and the DMS archive contains files with names invalid to MS-DOS
rules. If your Amiga disk compressed in the DMS archive contains a file
named as Amazing_Amiga.txt.info, it will fail. It works under Unix. Under
MS-DOS readdisk also changes the current working directory after its
execution, if you specify an output directory to it. This can cause some
problems too.
xDMS doesn't perform internal expansion of wildcards, but expects the
shell (or the compiler) to do it. It is the usual under unix. But if you
use it in a system where the shell does not perform wildcard expansion and
your compiler also does not generate code to perform it, then wildcards
will not work. This is the case, for example when using xDMS in the Amiga,
under the standard Amiga Shell, when compiled with SAS/C. I think Amiga
GCC adds wildcard expansion to the program it compiles. The same applies
to xDMS compiled with compilers like TurboC under MS-DOS. DJGPP for MSDOS
generate code to expand wildcards.
Acknowledgements:
-----------------
xDMS uses source code fragments or informations from the following public
domain or freeware programs:
Unix LHA by Masaru Oki : xDMS Heavy mode decrunch functions are based in
lha static lzh functions. DMS used parts of LHA and LZHUF in the first
place.
LZHUF by Haruyasu Yoshizaki : xDMS Deep mode decrunch functions are based
in LZHUF.
testdms by Bjorn Stenberg : I got some initial information about the DMS
headers with testdms, and also the CRC calculation function.
xDMS also calls, if available, gzip made by Jean-loup Gailly / Free
Software Foundation, and readdisk made by Bernd Schmidt
<crux pool.informatik.rwth-aachen.de>
Copyright:
----------
xDMS is released as public domain software. You can spread it, modify it
and use it in any way you like. You can do anything with it without even
asking me first. But I would like to know if you do something cool with
it.
How to contact the author:
--------------------------
If you have some problem, or have found a bug in xDMS, you can contact me
by e-mail. But first make sure you have read all this documentation.
The new maintainer:
Heikki Orsila
heikki.orsilaiki.fi
The old maintainer:
Andre' Rodrigues de la Rocha
adlrocusa.net |
