Contributor: ANTHONY GELAT
{
ANTHONY GELAT>>Is it the size of the EXE File? You can compress it With PKLite or>>LZEXE - it'll load into memory With full size, though. This just>Nope, it has self modifying data. PKLiting it wouldn't work.
I have code For a self modifying EXE that claims to be PKLITEable,
so i believe it can be done...here it is
}
Unit PCkSelfM;
{ Programmer: Jim Nicholson
Purpose: Implement a method For creating "self-modifying" .EXE Files from
TP which will survive the encoding techniques used by LZEXE and PKLite(tm).
For discussion and examples, see SelfMod.Pas
This Unit contains code placed into the public domain, With the following
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
provision:
Please do not distribute modified versions of this code Without indicating
such modification by commenting the File.
if you have questions, comments, modifications, or suggestions, please
feel free to contact us:
PCkS Associates
138 Frances Place
Hillside, NJ 07205
On CompuServe, EasyPlex to 70152,332
On Delphi CHICKENJN
On GENie J.NICHOLSON1
}
Interface
Var
ExeFileName : String[128];
Function ConfigBlockPresent(Size : Integer) : Boolean;
Function NewConfigBlock(Var C_B; Size : Integer) : Boolean;
Function ReadConfigBlock(Var C_B; Size : Integer) : Boolean;
Function ConfigBlockReWrite(Var C_B; Size : Integer) : Boolean;
Implementation
Uses
Dos;
Const
SelfModHeader : String[10] = 'PCkS SMODF';
CtrlZ : Char = ^Z;
Var
ExeFile : File;
Buffer : String[10];
Function ConfigBlockPresent(Size : Integer) : Boolean;
begin
assign(ExeFile, ExeFileName);
reset(ExeFile, 1);
seek(ExeFile, FileSize(ExeFile) - (SizeOf(SelfModHeader) + Size + 1));
BlockRead(ExeFile, Buffer, SizeOf(SelfModHeader));
if Buffer = SelfModHeader then
ConfigBlockPresent := True
else
ConfigBlockPresent := False;
close(ExeFile);
end;
Function NewConfigBlock(Var C_B; Size : Integer) : Boolean;
begin
NewConfigBlock := False;
if not ConfigBlockPresent(Size) then
begin
assign(ExeFile, ExeFileName);
reset(ExeFile, 1);
Seek(ExeFile, FileSize(ExeFile));
BlockWrite(ExeFile, SelfModHeader, SizeOf(SelfModHeader));
BlockWrite(ExeFile, C_B, Size);
BlockWrite(ExeFile, CtrlZ, 1);
close(ExeFile);
NewConfigBlock := True;
end;
end;
Function ReadConfigBlock(Var C_B; Size : Integer) : Boolean;
begin
ReadConfigBlock := False;
if ConfigBlockPresent(Size) then
begin
assign(ExeFile, ExeFileName);
reset(ExeFile, 1);
seek(ExeFile, FileSize(ExeFile) - (Size + 1));
BlockRead(ExeFile, C_B, Size);
close(ExeFile);
ReadConfigBlock := True;
end;
end;
Function ConfigBlockReWrite(Var C_B; Size : Integer) : Boolean;
Var
Temp : String;
begin
ConfigBlockReWrite := False;
if ConfigBlockPresent(Size) then
begin
assign(ExeFile, ExeFileName);
reset(ExeFile, 1);
seek(ExeFile, FileSize(ExeFile) - (SizeOf(SelfModHeader) + Size + 1));
BlockWrite(ExeFile, SelfModHeader, SizeOf(SelfModHeader));
BlockWrite(ExeFile, C_B, Size);
BlockWrite(ExeFile, CtrlZ, 1);
close(ExeFile);
ConfigBlockReWrite := True;
end;
end;
begin
ExeFileName := ParamStr(0);
end.
{--------------------------And SELFMOD.PAS, referenced above: }
Program SelfMod;
{
This demonstrates a technique For creating self-modifying .EXE Files. It
has an advantage over techniques which use Typed Constants, in that it will
survive LZEXEC and PkLite(tm).
Note that if the Program is run before LZEXEC is used to compress it, the
compressed Program will not have been initialized. This is because LZEXEC
strips off the config block (and everything else) at the end of the .EXE
File. This problem does not occur With PKLite(tm).
To run the demo, compile the Program and execute it twice. Whatever
String you enter is written to the end of the .EXE File.
To further demonstrate it's ablities, compress the File With PKLite(tm) or
LZEXEC after compiling.
Address all questions and comments to:
PCkS Associates
138 Frances Place
Hillside, NJ 07205
On CompuServe, EasyPlex to 70152,332
On Delphi CHICKENJN
On GENie J.NICHOLSON1
}
Uses
PCkSelfM;
Type
ConfigBlock = String[40];
Var
MyConfig : ConfigBlock;
begin
if ConfigBlockPresent(SizeOf(ConfigBlock)) then
if ReadConfigBlock(MyConfig, SizeOf(ConfigBlock)) then
begin
Writeln('Old value of MyConfig: ',MyConfig);
Write('Enter new value: ');
readln(MyConfig);
if ConfigBlockReWrite(MyConfig,SizeOf(ConfigBlock)) then
Writeln('Rewrote the block.')
else
Writeln('ConfigBlockReWrite failed.');
end
else
Writeln('ReadConfigBlock failed')
else
begin
Write('Enter inital value For MyConfig: ');
readln(MyConfig);
if NewConfigBlock(MyConfig, SizeOf(ConfigBlock)) then
Writeln('Created new config block')
else
Writeln('NewConfigBlock failed.');
end;
end.