VPLL - The Valkyrie PLL File Converter
Introduction
------------
The version of RTLink bundled with Clipper 5 introduced the use of
".PLL" files, which permitted runtime linking of a library with a
specially-prepared executable file. Unfortunately, this resulted in
files that Valkyrie was unable to recognize and process. This
limitation has now been overcome, with the use of the VPLL file
converter. This small utility creates a binary file that the Valkyrie
Preprocessor (VPP5.EXE) can recognize and work with; subsequently, the
Valkyrie translater (V5.EXE) can be run in a normal manner.
Usage
-----
The VPLL utility is command-line driven, with the following syntax:
[LOADFIX] VPLL <target.exe> <tempfile.exe>
<target.exe> = Filespec for the file that you
wish to process. You must include
the ".exe" file extension.
<tempfile.exe> = Filespec for temporary image file
that you will actually run VPP5
against. Keep this in the same
directory as the target .exe file.
Be careful to specify a DIFFERENT NAME
than the target file, or you could
overwrite your original .exe file!
Step 1:
It is necessary to tell the RTLink loader (RTLINKST.COM, which is
probably in your CLIPPER\BIN directory) where the PLL file is, by
setting an environmental variable ("PLL") to point to that directory.
From the command line, type the following, substituting the appropriate
path for your PLL directory. If you forget to do this, you will get an
error message from loader when it is accessed by the VPLL utility, and
the conversion will probably fail. (This variable may have already been
set as part of your normal Clipper installation.)
SET PLL=<path to directory containing BASE5?.PLL>
Step 2:
Run the VPLL utility from the DOS command line, as described above, to
prepare an image file. DO NOT TRY TO EXECUTE THIS IMAGE FILE, even
though it has an ".exe" file extension. At a minimum, it will probably
result in a "hung" machine. IT IS NOT A VALID EXECUTABLE FILE, DESPITE
THE ".EXE" FILE EXTENSION!
Step 3:
Run VPP5 from the command line, using the undocumented switch "/pll"
(or "/PLL"). This is important - if you omit this switch, VPP5 will not
recognize the image file as a valid executable.
VPP5 <tempfile.exe> /pll
Step 4:
Run Valkyrie (V5) and from the File Open menu, select the tempfile.exe
image file, NOT the original .exe file as the target. Valkyrie can
then decompile the application, referring to both the target and image
files as needed. Root procedures will be pulled from the image file,
and dynamically overlaid Clipper code will be recovered from the
original .exe file. This process is transparent, and you need not be
concerned about it.
Limitations
-----------
There must be enough free disk space for the image file, which will
typically be in the range of 300 - 500 Kilobytes. In addition, VPLL
requires slightly more free DOS memory than the target .exe file
normally requires to run.
Worth mentioning again: Be sure that the file you specify for the
tempfile is DIFFERENT from the target file name... otherwise, you may
destroy your original .exe file! And do NOT try to execute the temp
image file!
DOS 5 (and above) users may need to use the LOADFIX utility to run VPLL
since it is a small program and may otherwise end up running in the
lower 64K of memory. The syntax is:
LOADFIX VPLL <target.exe> <tempfile.exe>
