ProfitPress Mega CDROM2 …eeware (MSDOS)(1992)(Eng)/ProfitPress-MegaCDROM2.B6I/UTILITY/FILE/DISLT101.ZIP/DISLITE.DOC

Text File | 1992-04-14 | 18.9 KB | 425 lines

                                    DISLITE

                            Executable file expander



CONTENTS

         WARRANTY                           TECHS
     COPYING                            MESSAGES
         WHAT                               BUGS
         WHY                                PRICE
         HOW                                SOURCE
         LIMITS                             WHO



WARRANTY

   NONE! THIS PROGRAM COMES 'AS IS'. I CANNOT BE HELD RESPONSIBLE FOR
   ANY DAMAGE CAUSED BY THE USE OR MISUSE THIS PROGRAM. I CANNOT
   GUARANTEE THE FITNESS OF THIS PROGRAM FOR ANY PARTICULAR PURPOSE.
   IF THIS PROGRAM TURNS OUT TO BEHAVE UNEXPECTEDLY OR ERRONEOUSLY,
   THE USER IS RESPONSIBLE, AND I CANNOT BE FORCED TO SUPPLY THE USER
   WITH A FIX.

   So, now that I have the lawyers off my back (I hope), you can forget
   all that capsed crap above, and read the rest of the manual, in
   which I promise not to shout anymore.



COPYING

   You are free to distribute this program, provided that neither the
   program nor this document are changed, and the program and this
   document are kept together. Only a marginal fee may be asked for
   shipment and handling when distributing. You are not allowed to
   sell this program.

   Now that the black-market pirates are away too, we can get to business.



WHAT

   DISLITE expands all programs compressed by PKLITE (tm) to their
   original image. Expanding your files has many benefits over leaving
   them in their compressed state.

   Most important, the uncompressed image can be examined by other
   tools, such as virus scanners. A regular virus scanner can never
   detect a virus embedded in a compressed file (unless by executing
   and checking for suspicious actions), but on the uncompressed image
   a much faster pattern matching algorithm can be used.

   Then, PKLITE compressed programs can hardly be compressed any further
   using "regular" file compressors like ARJ, LHA. The uncompressed files
   however, usually compress quite well using these products, and normally
   the result of compressing the original file is better than that
   achieved when first compressing with PKLITE, and then with another
   compression utility. (Though not always)

   The same argument usually holds if you are using products like Stacker
   or SpeedStor to enlarge your disk, which could be considered as
   compression utilities on-the-fly. It would be silly to have a second,
   almost useless, compression slowing down your system.

   In a similar context can be mentioned that some people prefer other
   executable processors, such as DIET, to recompress the files.

   Then there is an increase in execution speed of uncompressed files,
   because the uncompression is no longer needed before execution. This
   may, on the other hand, not be true on fast machines with slow drives.
   In these circumstances the compressed file might actually execute
   quicker because there is less disk access.

   Finally, for the compression-hunters, there are a few extra's in this
   program that lets you strip unnecessary information off of the
   executables, making it a tad smaller.



WHY

   You could ask why this separate program is necessary, as PKLITE
   has the -x option to "extract" (I'd rather call it uncompress)
   a compressed files.

   The answer is simple. There is also an option in the commercial
   version of PKLITE to generate "unextractable" files (-e). Needless
   to say there are numerous programs available nowadays in this
   "unextractable" format. For those of us who don't like PKLITE for
   some reason, this presents a problem!

   DISLITE has the capability of expanding these "unextractable" files
   to their original image. Unfortunately some information is lost
   during the compression process of PKLITE, but there is no important
   information missing. See the TECHS section further on to get
   more details on this.



HOW

   Usage of DISLITE is very simple. If you type DISLITE without any
   arguments, a short help screen appears to remind you of the proper usage.
   If you specify the name of an executable file, DISLITE will expand that
   executable to its original state (provided it was compressed using
   PKLITE). If you specify two filenames, the second will be treated as
   the destination file, which will contain the decompressed image.
   Note that you do not need to specify the extension of the executables.
   Then there are several options which may occur anywhere on the command
   line.

   The official prototype of the command is as follows:

      DISLITE [options] [d:][/path]Infile [[d:][/path]Outfile]

      Options are:
        -b = make backup .BAK file of original
        -e = extract unextractable file
    -f = fix fixups also on normal compressed files
        -h = remove irrelevant header data
        -o = overwrite output file if it exists
        -p = align text data on a page
        -r = remove overlay data
        -s = silent, do not generate any warnings
        -u = update file time/date to current time/date
        -v = verbose

   Options can always be combined, so "-b -v -h" can be abbreviated as
   "-bvh". You can also use the switch character (usually '/', but it
   could be set to anything) as the option indicator. In case you use '/',
   the program tries to be smart and figures out whether you mean a
   filename or indeed an option (since you can use the '/' character as
   a directory separator too). In case of difficulty, use '-' and '\'.
   (More specific: DISLITE will only recognise an option initiated with
   '/' as option if every following character is a valid option.)

   A short description of all possible options follows:

   -b  This option makes a backup of the compressed file image, which
       has the same name and path as the Infile, but the extension .BAK.
       Any existing file with that name will be overwritten.

   -e  This option serves two purposes: First, to annoy Phil Katz, the
       original writer of the (quite good) program PKLITE. Second, to
       allow you more freedom in the creation of profane and filthy
       words with the option letters. To further support you in this,
       double specified options have no addition effect at all. The
       commonly heard rumour that the filthiest, profanest words will
       get you enhanced performance of DISLITE is absolutely untrue.
       This option is further completely ignored by the program.

   -f  Use this option if you previously got the "harmless warning: design
       thinko or linker cockup". With this option, DISLITE repairs a
       damaged fixup table in an .EXE file. Note that this is automatic
       on extra compressed files. It is, of course, useless on .COM files.
       See the MESSAGES section for more information on this.

   -h  Most linkers include in the exe file header some information that
       is not needed for program execution in any way, information that
       might be used by a debugger later. Use this option to remove that
       information from the executable. (For the technically gifted:
       the information between the end of the documented DOS header, and
       the start of the relocation table. PKLITE ignores all information
       after the relocation table in the header, so that is lost forever
       after using any PKLITE compression method.)
       Note that this option has no effect on .COM files as they have no
       exe header, and neither on extra-compressed files, as the extra
       header data is then removed by PKLITE on compression.

   -o  Use this option to overwrite an output file that already exists.
       Note that files with extensions .BAK and .$$$ with the name of
       the Infile are always overwritten (provided these files are
       generated by the program. You normally never see .$$$ but this
       is used as an interim file in case you only specify an Infile).

   -p  Align text data on a page. This option can be used for any .EXE
       file, to make the exe header a multiple of 512 bytes. Some say
       that the executable loads faster if this is the case.

   -r  Remove any overlay data present. Overlay data is data after the
       executable file image until the physical end of file. DISLITE
       never complains when overlays are present, it normally just copies
       the overlays.

   -s  Be silent. No warnings are given, and the header is suppressed
       too. Usefull for background or batch execution.

   -u  Update time. Use this option to set the file date/time stamp to
       the current time. Normally, DISLITE leaves the file date/time
       of the file the same (even when you specify an Outfile).

   -v  Be verbose. When you use this option, you will get a progress
       indicator, and lots and lots of information about the file
       being uncompressed. Recommended to the nosey.



LIMITS

   DISLITE uses quite a lot of memory. I haven't exactly calculated it,
   but I expect you need approximately 150K + the amount the expanded
   program takes to execute. In case you have not enough memory available,
   DISLITE will first try to shrink its buffers a little (upto a certain
   point), but this can lead to errors like "Too many fixups, sorry".

   In case anyone ever stumbles upon an executable that has more than
   16384 fixups, DISLITE gives up. I doubt any such file exists. I bet
   DOS gives up before that, because of the .EXE header exceeding 64K.

   The program uses the build-in extractor of the executable, and
   therefore a very smart virus can get hold of your system if you
   expand a compressed file which had a virus infecting it after
   compression. But since DISLITE disallows DOS and BIOS access for the
   expanding program, the chances that you actually catch a virus
   that infected a compressed file are much larger. See the TECHS
   section for more info.

   The "effective compression" ratio as described under MESSAGES can
   give odd or incorrect results if you specify one of the -hpr
   options.

   I haven't really tried to turn DISLITE into a speed demon. Especially
   the part where the resulting executable is written could be a little
   faster. That probably requires quite a thorough rewrite, though.



TECHS

   As said in the previous section, DISLITE uses the extractor build
   into the compressed file to decompress it. There is a little
   debugger inside DISLITE that allows it to only execute the build-in
   decompressor and extract information from it at the same time.
   Because of this, DISLITE is likely to work with future versions of
   PKLITE also, in case a slightly different encoding scheme is used.
   Currently DISLITE has been thoroughly tested with PKLITE versions
   upto 1.13, but it also works for the PKLITE 1.20 compressed files
   I could lay my hands on.

   When debugging the program that is decompressed, DOS and BIOS
   interrupts are disabled. But in case such an interrupt is called
   anyway, DISLITE displays the offending interrupt number and follows
   with a dump of all internal registers. This might indicate several
   things: If you had previous warnings about an unrecognised PKLITE
   version, that is likely to be cause of the troubles. If you
   haven't, someone might have modified the compressed program.
   This modification could have been done by the original programmer
   on purpose, or, as a final case, by a virus.

   .COM files are always extracted to their original image, and so are
   normal compressed .EXE files. (Well, at least restored just as
   PKLITE -x would restore them. If there was any information stored
   after the relocation table, that is lost.)

   Extra compressed .EXE files can not be restored to their original
   image exactly. As said before, the information stored in the header
   just after the DOS documented .EXE header and before the relocation
   table cannot be recovered. This information is not needed anyway.
   Further, there are 3 entries in the .EXE header that can not be
   recovered completely. Two of these, the headersize and the position
   of the relocation table follow from the fact that the additional
   header data is lost.

   The third entry that can not be completely recovered is the minimum
   memory to allocate to the program. This value might be a little bigger
   in the newly extracted image as compared to the original one. In case
   you have such a critical memory setup that the program cannot execute
   with this larger minimum memory requirement, it wouldn't have done so
   *with* the PKLITE decompression code either. Resuming, this is again not
   a great loss.

   However, DISLITE is very well able to *completely* restore the relocation
   or fixup table. In fact DISLITE goes through some trouble finding the
   right segment for each fixup, as PKLITE -e kindly throws that information
   away.



MESSAGES

   Many! DISLITE is stuffed to under its chin with all kinds of information
   messages, most of which are self-explanatory. I will, however, name
   some.

   There are four types of messages DISLITE can produce: informational,
   harmless warnings, warnings, and errors.

   Informational messages are enabled with the -v option. They include:
   progress indicators, and various file information. There are two
   compression ratio's mentioned for .EXE files: the real compression and
   the effective compression. The real compression is the compression of
   text (executable) data, as achieved by the PKLITE algorithms, and the
   effective compression is the file-to-file overall compression factor,
   the one that PKLITE displays. This latter value might not be correct
   in all circumstances. See the LIMITS section.


   There are only two harmless warnings (and turned off with -s):

      Harmless warning: design thinko or linker cockup.
      Fixup XXXX:XXXX out of segment (should be in XXXX)
      ...

   This can only occur if you are extracting a normal compressed .EXE
   file. It means that DISLITE found a fixup to be incorrectly
   specified in the wrong segment. No harm is done, however, since the
   fixup is applied to the same file location nevertheless. This either
   means that there is a major design flaw in DISLITE or, more probably,
   some linker (or other expander software) has made an error. This is
   likely to happen if you expand a file that has previously been
   compressed with LZEXE, uncompressed with an old version of UNLZEXE,
   and then immediately compressed with PKLITE again, without using
   HDROPT first. (Newer versions of PKLITE have HDROPT build in, though).

   What this effectively means is, that if this would have been an extra
   compressed file, DISLITE would have rebuild it in a different way.
   If your esteem of aesthetics is high, and you can not tolerate such
   faulty fixups in your files, you should apply the -f option. This will
   cause DISLITE to fix the fixups for you.

   The other harmless warning reports that a relative segment in the .EXE
   is ignored. Not likely to happen.

   The program will complete like nothing happened after a harmless warning.


   Warnings are given if you try to expand a program that has no executable
   extension, if you are expanding a program that has an .EXE extension but
   is in fact a .COM file or vice versa, if you are expanding a program
   that was compressed with an unknown version of PKLITE (pre 1.03 or post
   1.20), or if the program has unknown internal PKLITE flags set.

   You are asked to confirm before proceeding. Again, setting -s turns this
   all off.

   A warning that doesn't ask for permission before proceeding, is the
   one generated when DISLITE detects incorrect original header data in a
   normal compressed .EXE file. DISLITE just assumes it is an extra
   compressed .EXE file, calculates the header on its own, and proceeds.
   You can no longer fool DISLITE by resetting the "extra" flag bit on an
   extra compressed file.


   There are innumerable errors, mostly DOS errors of the format
   "short explanation:DOS error description". These are all of the type
   "get your dirty hands off that disk drive door and retry". DISLITE
   can't do much about it.

   There are some DISLITE specific errors, like "Cannot find end of
   decode loop."; or "Unexpected interrupt xxh from processed program.",
   followed by a dump of all CPU registers; or "Not enough memory." or
   "Too many fixups, sorry."

   This all means that DISLITE can no longer keep track of what's happening,
   and gives up. Increasing the memory available to DISLITE might help.
   If it doesn't, blame PKWARE for bringing out an incompatible version of
   PKLITE. (And start looking for an updated DISLITE :-)

   The only likely error is that of an unexpected exit from the compressed
   program, which normally means you pressed Ctrl-Break.

   You cannot turn off the errors or stop them from aborting the program.



BUGS

   Just one, but I can't find it. ;-(
   In case you do, please notify me (see the WHO section below).



PRICE

   Zero. Give this away to all your friends, especially if their initials
   are PK ;-) But of course donations are greatly appreciated. See the
   WHO section below to know where to send your money.



SOURCE

   Might be messy. I've written the lot using Borland C++ 2.0. The main
   routines are in C, but the taskswitching routines for the debugger are
   all in assembly. Now that it's finished I realise how it all Should Have
   Been Done (tm), but it's too late for that now, I guess.

   If you want to take a look at the source, it is available, but not for
   free. If you think you can learn something from this source then I
   can *certainly* make you think that you should pay me before I hand out
   that source.

   The price is HFL 25,- DM 25,- or AM$ 20 (Yes, the Germans are screwed
   by this, sorry...). See the WHO section below to find out where you
   should sent your payment too. Please include an internet E-mail or
   FidoNet address where I can send the source to. If you don't, include
   a self-addressed envelope. Specify how you want to receive the source:
   diskette or paper. Yes, I pay for the shipment & handling. And for
   the diskette, if any.



WHO

   I can be reached:

      Jan-Pieter Cornet
      Aletta Jacobsstraat 8
      2642 AD  Pijnacker
      Netherlands
      phone: [phone]
      Email: [e-mail]
          or [e-mail]

      Dutch Bank: ABN Bank Delft, 562217320, tnv. J.P.M. Cornet
      Dutch Giro: 1444902, tnv. J.P.M. Cornet, Pijnacker


   DISLITE (pd)   Executable File Expander   Version 1.01   14-04-92
   Written 1991-1992 JohnPC.   No rights reserved.   Blatant bending