upx.html

非常好的可执行文件压缩软件

<P>
Extra options available for this executable format:

<P>
<PRE>  --8086              Create an executable that works on any 8086 CPU.
</PRE>
<P>
<PRE>  --no-reloc          Use no relocation records in the exe header.
</PRE>
<P>
<HR>
<H2><A NAME="NOTES_FOR_DOS_SYS">NOTES FOR DOS/SYS</A></H2>
<P>
You can only compress plain sys files, sys/exe (two in one) combos are not
supported.

<P>
Compressed programs only work on a 286+.

<P>
Packed programs will be byte-identical to the original after uncompression.

<P>
Maximum uncompressed size: ~65350 bytes.

<P>
Extra options available for this executable format:

<P>
<PRE>  --8086              Create an executable that works on any 8086 CPU.
</PRE>
<P>
<HR>
<H2><A NAME="NOTES_FOR_DJGPP2_COFF">NOTES FOR DJGPP2/COFF</A></H2>
<P>
First of all, it is recommended to use UPX *instead* of <STRONG>strip</STRONG>. strip has the very bad habit of replacing your stub with its own
(outdated) version. Additionally UPX corrects a bug/feature in strip
v2.8.x: it will fix the 4 KByte aligment of the stub.

<P>
UPX includes the full functionality of stubify. This means it will
automatically stubify your COFF files. Use the option <STRONG>--coff</STRONG> to disable this behaviour (see below).

<P>
UPX automatically handles Allegro packfiles.

<P>
The DLM format (a rather exotic shared library extension) is not supported.

<P>
Packed programs will be byte-identical to the original after uncompression.
All debug information and trailing garbage will be stripped, though.

<P>
BTW, UPX is the successor of the DJP executable packer.

<P>
Extra options available for this executable format:

<P>
<PRE>  --coff              Produce COFF output instead of EXE. By default
                      UPX keeps your current stub.
</PRE>
<P>
<HR>
<H2><A NAME="NOTES_FOR_LINUX_i386">NOTES FOR LINUX/i386</A></H2>
<P>
How it works:

<P>
<PRE>  Because Linux is a real operating system, the in-place in-memory
  decompression scheme used in the other executable formats doesn't
  work here.
</PRE>
<P>
<PRE>  Instead we must use temporary decompression to disk. Interestingly -
  because of the good memory management of the Linux kernel - this
  often does not introduce a noticable delay, and in fact there
  will be no disk access at all if you have enough free memory as
  the entire process takes places within the filesystem buffers.
</PRE>
<P>
<PRE>  A compressed executable consists of the UPX stub and an overlay
  which contains the original program in a compressed form.
</PRE>
<P>
<PRE>  The UPX stub is a statically linked ELF executable and does
  the following at program startup:
</PRE>
<P>
<PRE>    1) decompress the overlay to a temporary location in /tmp
    2) open the temporary file for reading
    3) try to delete the temporary file and start (execve)
       the uncompressed program in /tmp using /proc/&lt;pid&gt;/fd/X as
       attained by step 2)
    4) if that fails, fork off a subprocess to clean up and
       start the program in /tmp in the meantime
</PRE>
<P>
<PRE>  The UPX stub is about 1700 bytes long, partly written in assembler
  and only uses kernel syscalls. It is not linked against any libc.
</PRE>
<P>
Benefits:

<P>
<PRE>  - UPX can compress all executables, be it AOUT, ELF, libc4, libc5,
    libc6, Shell/Perl/Python/... scripts, standalone Java .class
    binaries, or whatever...
    All scripts and programs will work just as before.
</PRE>
<P>
<PRE>  - Compressed programs are completely self-contained. No need for
    any external program.
</PRE>
<P>
<PRE>  - UPX keeps your original program untouched. This means that
    after decompression you will have a byte-identical version,
    and you can use UPX as a file compressor just like gzip.
    [ Note that UPX maintains a checksum of the file internally,
      so it is indeed a reliable alternative. ]
</PRE>
<P>
<PRE>  - As the stub only uses syscalls and isn't linked against libc it
    should run under any Linux configuration that can run ELF
    binaries and has working /proc support.
</PRE>
<P>
<PRE>  - For the same reason compressed executables should run under
    FreeBSD and other systems which can run Linux binaries.
    [ Please send feedback on this topic ]
</PRE>
<P>
Drawbacks:

<P>
<PRE>  - You need additional free disk space for the uncompressed program
    in your /tmp directory. This program is deleted immediately after
    decompression, but you still need it for the full execution time
    of the program.
</PRE>
<P>
<PRE>  - You must have /proc filesystem support as the stub wants to open
    /proc/&lt;pid&gt;/exe and needs /proc/&lt;pid&gt;/fd/X. This also means that you
    cannot compress programs that are used during the boot sequence
    before /proc is mounted.
</PRE>
<P>
<PRE>  - `ldd' and `size' won't show anything useful because all they
    see is the statically linked stub (since version 0.82 the section
    headers are stripped from the UPX stub and `size' doesn't even
    recognize the file format any longer - looks like a binutils bug).
</PRE>
<P>
<PRE>  - Utilities like `top' will display numerical values in the process
    name field. This is because Linux computes the process name from
    the first argument of the last execve syscall (which is typically
    something like /proc/&lt;pid&gt;/fd/3).
</PRE>
<P>
<PRE>  - To reduce memory requirements during uncompression UPX splits the
    original file into blocks, so the compression ratio is a little bit
    worse than with the other executable formats (but still quite nice).
    [ Advise from kernel experts which can tell me more about the
      execve memory semantics is welcome. Maybe this shortcoming
      could be removed. ]
</PRE>
<P>
<PRE>  - Because of temporary decompression to disk the decompression speed
    is not as fast as with the other executable formats. Still, I can see
    no noticable delay when starting programs like my ~3 MB emacs (which
    is less than 1 MB when compressed :-).
</PRE>
<P>
Notes:

<P>
<PRE>  - As UPX leaves your original program untouched it is advantageous
    to strip it before compression.
</PRE>
<P>
<PRE>  - It is not advisable to compress programs which usually have many
    instances running (like `make') because the common segments of
    compressed programs won't be shared any longer between different
    processes.
</PRE>
<P>
<PRE>  - If you compress a script you will lose platform independence -
    this could be a problem if you are using NFS mounted disks.
</PRE>
<P>
<PRE>  - Compression of suid, guid and sticky-bit programs is rejected
    because of possible security implications.
</PRE>
<P>
<PRE>  - For the same reason there is no sense in making any compressed
    program suid.
</PRE>
<P>
<PRE>  - Obviously UPX won't work with executables that want to read data
    from themselves. E.g., this might be a problem for Perl scripts
    which access their __DATA__ lines.
</PRE>
<P>
<PRE>  - In case of internal errors the stub will abort with exitcode 127.
    Typical reasons for this to happen are that the program has somehow
    been modified after compression, you have run out of disk space
    or your /proc filesystem is not yet mounted.
    Running `strace -o strace.log compressed_exe' will tell you more.
</PRE>
<P>
Extra options available for this executable format:

<P>
<PRE>  (none)
</PRE>
<P>
<HR>
<H2><A NAME="NOTES_FOR_RTM32_PE">NOTES FOR RTM32/PE</A></H2>
<P>
Same as win32/pe.

<P>
<HR>
<H2><A NAME="NOTES_FOR_TMT_ADAM">NOTES FOR TMT/ADAM</A></H2>
<P>
This format is used by the TMT Pascal compiler - see <A
HREF="http://www.tmt.com/">http://www.tmt.com/</A> .

<P>
Extra options available for this executable format:

<P>
<PRE>  (none)
</PRE>
<P>
<HR>
<H2><A NAME="NOTES_FOR_WATCOM_LE">NOTES FOR WATCOM/LE</A></H2>
<P>
UPX has been successfully tested with the following extenders: DOS4G,
DOS4GW, PMODE/W, DOS32a, CauseWay. The WDOS/X extender is partly supported
(for details see the file bugs BUGS).

<P>
Yes, you can use your compressed executables with DOS4GW.

<P>
The LX format is not yet supported.

<P>
DLLs are not supported.

<P>
Extra options available for this executable format:

<P>
<PRE>  --le                Produce an unbound LE output instead of
                      keeping the current stub.
</PRE>
<P>
<HR>
<H2><A NAME="NOTES_FOR_WIN32_PE">NOTES FOR WIN32/PE</A></H2>
<P>
The PE support in UPX is quite stable now, but definitely there are still
some incompabilities with some files.

<P>
Because of the way UPX (and other packers for this format) works, you can
see increased memory usage of your compressed files. If you start several
instances of huge compressed programs you're wasting memory because the
common segements of the program won't get shared across the instances. On
the other hand if you're compressing only smaller programs, or running only
one instance of larger programs, then this penalty is smaller, but it's
still there.

<P>
If you're running executables from network, then compressed programs will
load faster, and require less bandwidth during execution.

<P>
DLLs are supported.

<P>
Extra options available for this executable format:

<P>
<PRE> --compress-exports=0 Don't compress the export section.
                      Use this if you plan to run the compressed
                      program under Wine.
 --compress-exports=1 Compress the export section. [DEFAULT]
                      Compression of the export section can improve the
                      compression ratio quite a bit but may not work
                      with all programs (like winword.exe).
                      UPX never compresses the export section of a DLL
                      regardless of this option.
</PRE>
<P>
<PRE>  --compress-icons=0  Don't compress any icons.
  --compress-icons=1  Compress all but the first icon.
  --compress-icons=2  Compress all icons which are not in the
                      first icon directory. [DEFAULT]
</PRE>
<P>
<PRE>  --compress-resources=0  Don't compress any resources at all.
</PRE>
<P>
<PRE>  --force             Force compression even when there is an
                      unexpected value in a header field.
                      Use with care.
</PRE>
<P>
<PRE>  --strip-relocs=0    Don't strip relocation records.
  --strip-relocs=1    Strip relocation records. [DEFAULT]
                      This option only works on executables with base
                      address greater or equal to 0x400000. Usually the
                      compressed files becomes smaller, but some files
                      may become larger. Note that the resulting file will
                      not work under Win32s.
                      UPX never strips relocations from a DLL
                      regardless of this option.
</PRE>
<P>
<HR>
<H1><A NAME="DIAGNOSTICS">DIAGNOSTICS</A></H1>
<P>
Exit status is normally 0; if an error occurs, exit status is 1. If a
warning occurs, exit status is 2.

<P>
<STRONG>UPX</STRONG>'s diagnostics are intended to be self-explanatory.

<P>
<HR>
<H1><A NAME="BUGS">BUGS</A></H1>
<P>
Please report all bugs immediately to the authors.

<P>
<HR>
<H1><A NAME="AUTHORS">AUTHORS</A></H1>
<P>
<PRE> Markus F.X.J. Oberhumer &lt;[e-mail]&gt;
 <A HREF="http://wildsau.idv.uni-linz.ac.at/mfx/upx.html">http://wildsau.idv.uni-linz.ac.at/mfx/upx.html</A>
</PRE>
<P>
<PRE> Laszlo Molnar &lt;[e-mail]&gt;
 <A HREF="http://www.nexus.hu/upx">http://www.nexus.hu/upx</A>
</PRE>
<P>
<HR>
<H1><A NAME="COPYRIGHT">COPYRIGHT</A></H1>
<P>
Copyright (C) 1996-2000 Markus Franz Xaver Johannes Oberhumer Copyright (C)
1996-2000 Laszlo Molnar

<P>
This program may be used freely, and you are welcome to redistribute it
under certain conditions.

<P>
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the UPX License Agreement for more
details.

<P>
You should have received a copy of the UPX License Agreement along with
this program; see the file LICENSE. If not, visit the UPX home page.

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