mirror of
https://github.com/upx/upx.git
synced 2024-11-27 14:40:25 +00:00
145 lines
4.0 KiB
Plaintext
145 lines
4.0 KiB
Plaintext
The UPX Hacker's Guide
|
|
======================
|
|
|
|
|
|
Foreword
|
|
--------
|
|
|
|
The precompiled UPX versions are linked against the NRV compression
|
|
library instead of the UCL library. Using the same compression algorithms,
|
|
NRV achieves a better compression ratio. NRV is not publicly
|
|
available, though, and probably never will be.
|
|
|
|
While you may be disappointed that you don't have access to the
|
|
latest state-of-the-art compression technology this is actually
|
|
a safe guard for all of us. The UPX source code release makes
|
|
it very easy for any evil-minded person to do all sort of bad
|
|
things. By not providing the very best compression ratio it is much
|
|
more difficult to create fake or otherwise disguised UPX versions (or
|
|
similar trojans), as any end user will notice when the compression
|
|
has gotten worse with a new "version" or "product".
|
|
|
|
Finally please be aware that you now have your hands on the source
|
|
code of the most sophisticated executable packer ever.
|
|
Let's join our forces to make it even better :-)
|
|
|
|
Share and enjoy,
|
|
Markus & Laszlo
|
|
|
|
|
|
Introduction
|
|
------------
|
|
|
|
Welcome to the UPX source code release!
|
|
|
|
UPX is not a toy for kids. Apart from basic knowledge about executables
|
|
and data compression you will need to be firm in C++, assembler,
|
|
Perl and Makefiles. Probably some other things as well.
|
|
|
|
If you can't manage to compile it then the sources are
|
|
probably not for you. Don't email us for help.
|
|
|
|
The authors use Linux for development. You might want to as well.
|
|
|
|
|
|
Short overview
|
|
--------------
|
|
|
|
The UPX source code consists of two mainly independent parts:
|
|
|
|
1) The src/stub directory contains the decompression stubs that
|
|
will get added to each compressed executable.
|
|
The stubs are mainly written in assembler and get "compiled"
|
|
into ordinary C header files.
|
|
|
|
2) The src directory contains the actual packer sources. The stubs
|
|
are #included by the individual executable format handlers.
|
|
|
|
|
|
Prerequisites
|
|
-------------
|
|
|
|
- first of all you need to build the UCL compression library
|
|
http://www.oberhumer.com/opensource/ucl/
|
|
|
|
|
|
Tools needed to build/modify the UPX sources
|
|
--------------------------------------------
|
|
|
|
- A C++ compiler supporting inner classes, templates, exceptions
|
|
and RTTI.
|
|
|
|
- GNU make 3.80 or better (GNU make 3.81 recommened).
|
|
|
|
|
|
To compile the packer sources
|
|
-----------------------------
|
|
|
|
Set the environment variable UPX_UCLDIR to point to your
|
|
UCL build directory, e.g.
|
|
|
|
set UPX_UCLDIR=c:\src\ucl-1.03 (DOS / Windows)
|
|
export UPX_UCLDIR=$HOME/local/src/ucl-1.03 (Unix)
|
|
|
|
Set the environment variable UPX_LZMADIR to point to your
|
|
to your unpacked lzma443.tar.bz2 source directory, e.g.
|
|
|
|
export UPX_LZMADIR=$HOME/local/src/lzma-4.43 (Unix)
|
|
|
|
Finally type
|
|
|
|
make
|
|
|
|
|
|
If you want to modify the stub sources you'll also need
|
|
-------------------------------------------------------
|
|
|
|
- GNU make 3.81 or better
|
|
http://savannah.gnu.org/projects/make/
|
|
|
|
- Perl & Python
|
|
|
|
- A number of cross-assemblers and cross-compilers - precompiled
|
|
binaries for i386-linux hosts are available from
|
|
http://sourceforge.net/project/showfiles.php?group_id=2331
|
|
|
|
|
|
Misc. notes
|
|
-----------
|
|
|
|
As the docs say: UPX is a portable, extendable and endian neutral
|
|
program, so if you want to add some new stuff, try not to break these
|
|
nice properties.
|
|
|
|
- Use the types LE16, LE32, BE16 and BE32 for fields in file headers.
|
|
- Use [sg]et_[bl]e(16|32) for getting/setting values in the data
|
|
stream.
|
|
- Use gcc extensions and other compiler specific stuff only through
|
|
macros.
|
|
|
|
***
|
|
|
|
Some conventions:
|
|
|
|
- follow our coding style
|
|
- indent level = 4
|
|
- expand all tabulators
|
|
|
|
- Use throwSomeException() functions instead of throw SomeException():
|
|
this makes the code shorter if used often.
|
|
|
|
***
|
|
|
|
Patches/Contributions
|
|
|
|
- Please send us bug fixes/contributions only using
|
|
|
|
diff -u oldfile newfile
|
|
|
|
or
|
|
|
|
diff -uNr olddirectory newdirectory
|
|
|
|
|
|
# vi:ts=4:et
|