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<h1>The International Obfuscated C Code Contest</h1>
|
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<h2>2001/anonymous - Dishonorable mention</h2>
|
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|
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<a class="Left Disabled" href="#">first entry</a>
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<a class="Left" href="../index.html">↑ 2001 ↑</a>
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<a class="Left" href="../bellard/index.html">bellard →</a>
|
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<a class="Right" href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.c">C code</a>
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<a class="Right" href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/Makefile">Makefile</a>
|
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<a class="Right" href="#inventory">Inventory</a>
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<a class="Right" href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fioccc-src.github.io%2Ftemp-test-ioccc%2F2001%2Fanonymous%2Findex.html">✓</a>
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<!-- START: this line starts content generated by: bin/output-index-author.sh -->
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<h2 id="author">Author:</h2>
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||
<ul>
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<li>Name: <a href="../../authors.html#Anonymous_2001">Anonymous 2001</a><br>
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Location: <a href="../../location.html#GB">GB</a> - <em>United Kingdom of Great Britain and Northern Ireland</em> (<em>United Kingdom</em>)</li>
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<!-- BEFORE: 1st line of markdown file: 2001/anonymous/README.md -->
|
||
<h2 id="to-build">To build:</h2>
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||
<pre><code> make</code></pre>
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<p>The programs that this program is supposed to act on,
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||
<a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.ten.c">anonymous.ten.c</a> and <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.bed.c">anonymous.bed.c</a>,
|
||
compiled with <code>make</code>, MUST be compiled as 32-bit ELF binaries. In the case that
|
||
this fails these programs will be compiled as 64-bit binaries as alternate code,
|
||
<code>anonymous.ten.alt</code> and <code>anonymous.bed.alt</code>, ELF or otherwise. However trying to
|
||
use the entry on these files will fail. See <a href="#alternate-code">Alternate code</a>
|
||
below for information on how to compile these programs as 64-bit binaries (or
|
||
whatever your system will compile them as).</p>
|
||
<h3 id="bugs-and-misfeatures">Bugs and (Mis)features:</h3>
|
||
<p>The current status of this entry is:</p>
|
||
<blockquote>
|
||
<p><strong>STATUS: INABIAF - please DO NOT fix</strong></p>
|
||
</blockquote>
|
||
<p>For more detailed information see <a href="../../bugs.html#2001_anonymous">2001/anonymous in bugs.html</a>.</p>
|
||
<h2 id="to-use">To use:</h2>
|
||
<pre><code> ./anonymous x86_program</code></pre>
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<h2 id="try">Try:</h2>
|
||
<pre><code> ./try.sh
|
||
|
||
./anonymous anonymous.bed # if able to compile as a 32-bit (-m32) ELF binary</code></pre>
|
||
<p>NOTE: if the 32-bit version cannot be compiled the script will at least compile
|
||
<a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.ten.c">anonymous.ten</a> as a 64-bit program (or whatever your system is
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||
set to) and run it directly.</p>
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||
<p>What happens if the x86 program has already been modified by this program? The
|
||
judges’ remarks below might give you a hint!</p>
|
||
<p>What happens if you try it on another file like <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.c">anonymous.c</a>? Can
|
||
you recompile it okay? What if you run it on <code>anonymous</code> itself? Can you run the
|
||
program successfully after it without recompiling?</p>
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||
<h2 id="alternate-code">Alternate code:</h2>
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||
<p>In the case you you wish to manually compile the extra programs as 64-bit code
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||
you may do so. Using the entry on these binaries will very likely crash the
|
||
program or do something terribly wrong like slaughtering all the
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||
<a href="https://www.glyphweb.com/arda/e/elves.html">elves</a> of
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||
<a href="https://www.glyphweb.com/arda/i/imladris.php">Imladris</a>! :-) so please don’t do
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that :-(</p>
|
||
<h3 id="alternate-build">Alternate build:</h3>
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<pre><code> make alt</code></pre>
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<h3 id="alternate-use">Alternate use:</h3>
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<pre><code> ./anonymous.ten.alt
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./anonymous.bed.alt</code></pre>
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<h3 id="a-2023-note-about-the-warning-from-the-author">A 2023 note about the warning from the author:</h3>
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<p>The author suggested that this <em>might</em> somewhat destroy the binaries this
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touches but after the fix of 2023 this was not observed (yet?). It does indeed
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||
modify the files (though not all files are modified: can you figure out why that
|
||
is?) but using them after did not result in any problems. It could be that it’s
|
||
no longer known exactly what is supposed to happen and possibly that the
|
||
modification might not be entirely correct for that reason though it does appear
|
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to be correct.</p>
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<p>It appears that the corruption happens only if the modification fails in the
|
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middle of doing so so that might be why it hasn’t been observed.</p>
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||
<h2 id="judges-remarks">Judges’ remarks:</h2>
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||
<p>Is emulation the sincerest form of flattery? This small program does
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||
quite a lot of bit twiddling.</p>
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||
<h2 id="authors-remarks">Author’s remarks:</h2>
|
||
<p>This program is an optimizing dynamic binary translator, allowing you to
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||
run x86 programs on any machine (x86 or otherwise).</p>
|
||
<p>I have included a simple <a href="https://www.bbc.co.uk/teach/school-radio/nursery-rhymes-ten-green-bottles/zncyt39">10 Green
|
||
Bottles</a>
|
||
<a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.ten.c">program</a> (try <code>make anonymous.ten</code>), meant to be compiled as a
|
||
32-bit ELF binary.</p>
|
||
<p>The program <code>anonymous.ten</code>, and its source (dull) are included as data
|
||
files.</p>
|
||
<h3 id="warning">Warning</h3>
|
||
<p>Note that the translator screws around with the binary you run on it and <em>might</em>
|
||
corrupt the binary to some extent and in so doing might leave any program you
|
||
run on it unusable.</p>
|
||
<p>The build script should give an example command to compile the program.</p>
|
||
<h3 id="features">Features</h3>
|
||
<p><a href="https://en.wikipedia.org/wiki/Basic_block">Basic Block</a>
|
||
<a href="https://en.wikipedia.org/wiki/Cache_(computing)">Cache</a>: Rather than
|
||
translating each instruction individually the dynamic binary translator
|
||
generates a translation for an entire basic block of subject code. Having
|
||
translated a block once, the target code generated will be stored for the
|
||
duration that the program is running, so as a program runs its performance will
|
||
improve, as it hits cached blocks. This can be clearly observed in the example
|
||
program, <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.ten.c">anonymous.ten</a> which must be compiled as a 32-bit ELF
|
||
binary.</p>
|
||
<h3 id="target-library-linking">Target Library Linking:</h3>
|
||
<p>The program runs <a href="https://en.wikipedia.org/wiki/Dynamic_linker">dynamically
|
||
linked</a> <a href="https://en.wikipedia.org/wiki/Executable_and_Linkable_Format">ELF
|
||
binaries</a>, and
|
||
when the subject program attempts to make a call to a standard
|
||
<a href="https://en.wikipedia.org/wiki/Library_(computing)">library</a>, the translator
|
||
attempts to make an appropriate call to the native system libraries on the
|
||
target machine. This involves mangling between different calling conventions,
|
||
etc.</p>
|
||
<h3 id="automatic-endian-detectionreversal">Automatic Endian Detection/Reversal:</h3>
|
||
<p>There are various problems raised when attempting to run little
|
||
<a href="https://en.wikipedia.org/wiki/Endianness">endian</a>
|
||
<a href="https://en.wikipedia.org/wiki/X86">x86</a> code on a big endian chip, such as a
|
||
<a href="https://en.wikipedia.org/wiki/PowerPC">PPC</a>. These problems are dealt
|
||
with in a manner that is entirely transparent to the user.</p>
|
||
<h3 id="configuration">Configuration:</h3>
|
||
<h4 id="warnings">Warnings:</h4>
|
||
<p>By default the build script should compile the program with a set of
|
||
switches such that while compiling the program it generates one error
|
||
(which I feel is useful advice). The program should generate no further
|
||
compiler errors while it is running (yes, the program can generate
|
||
compiler errors while it is running). If you do not wish to see this
|
||
error, or if the program generates any further error when compiled using
|
||
your C compiler please remove the <code>-Dwarning='-Dprocessor'</code> line and the
|
||
<code>$$warning</code> from the compiler invocation.</p>
|
||
<h3 id="optimization">Optimization</h3>
|
||
<p>The build script contains a <code>-O1</code> switch for the compiler. Increasing
|
||
the optimization level will make the program run <em>slower</em>, while
|
||
compiling the program without any optimization will allow it to run
|
||
<em>faster</em>.</p>
|
||
<h3 id="obfuscation">Obfuscation</h3>
|
||
<p>The most obvious part of the obfuscation is probably the mess of <code>#define</code>s at the
|
||
top. This may seem a somewhat tired old obfuscation - however since many of
|
||
these macros are (sometimes only) used by the program once it has dynamically
|
||
recompiled itself, they are only referenced within the source code from within
|
||
strings - and therefore the macros cannot be expanded. Furthermore, some of
|
||
these strings of code are not given as strings, but instead are wrapped up in
|
||
macros that use the <code>#</code> preprocessor operator to turn them into strings. In the
|
||
hope of throwing off a few C beautifiers the macro to generate the strings is
|
||
not contained within the source code but instead is passed in on the command
|
||
line.</p>
|
||
<p>Buried under all this, and the fact that the entire program is just a
|
||
call to <code>exit(3)</code>, there are some nice subtle little obfuscations. For
|
||
example, you may notice that there are a couple of macros that use the
|
||
<code>##</code> preprocessor operator to build pairs of functions. One of these
|
||
macros is used to build pairs of functions of which only one has
|
||
local variables which shadow global variables: so one modifies the
|
||
global state, and the other doesn’t.</p>
|
||
<p>There is also quite a nice trick where I wave a magic wand, and a chunk of code
|
||
which should only be run when the program is run for the first time (setting the
|
||
<a href="https://en.wikipedia.org/wiki/Program_counter">PC / IP</a> to point at <code>main()</code>
|
||
etc.) gets turned into a <del>frog</del>string. The C compiler sees a string by
|
||
itself in the code, thinks “yup, that’s a valid C expression”, and quietly moves
|
||
on to the next line of code.</p>
|
||
<h3 id="limitations">Limitations</h3>
|
||
<p>Due to space limitations only a handful of instructions are supported; these
|
||
instructions which are supported are supported in somewhat non-conventional
|
||
ways: chunks of the architecture (e.g. flags) are just ignored, the ELF
|
||
<a href="https://en.wikipedia.org/wiki/Loader_(computing)">loader</a> does not really load
|
||
the <a href="https://en.wikipedia.org/wiki/Executable_and_Linkable_Format">ELF binary</a>,
|
||
the target <a href="https://en.wikipedia.org/wiki/Linker_(computing)">library linking</a>
|
||
can only pass up to 3 parameters to the target library function, etc.</p>
|
||
<p>In short, please consider this a full disclaimer for any bug that may
|
||
turn up - yes the program is unsafe, but it’s pretty cool anyway.</p>
|
||
<p>Despite all this, the translator is not exclusively limited to running the
|
||
<a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.ten.c">anonymous.ten</a> program. Other trivial <strong><em>x86</em></strong> programs may
|
||
run on the translator - and I have successfully run a wide range of “Hello
|
||
World” programs, including one of last year’s IOCCC entries,
|
||
<a href="../../2000/tomx/index.html">2000/tomx</a>.</p>
|
||
<h3 id="complete-program">Complete Program</h3>
|
||
<p>The fact that the program makes calls to <code>system(3)</code> and <code>execv(3)</code> may imply that
|
||
it is not a complete program in its own right, as it relies on other programs.
|
||
The call to <code>system(3)</code> is a call to ask gcc to recompile the translator with a
|
||
new set of switches, and the call to <code>execv(3)</code> asks for the newly compiled
|
||
program to be executed. I would point out that almost every other entry to this
|
||
competition also require a C compiler (well, the published winning entries at any rate,
|
||
and I recognize that a few don’t). There is little real difference between this
|
||
program and one like last year’s entry <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/dhyang/dhyang.c">dhyang</a>; both are
|
||
just C programs that generate C code as their output.</p>
|
||
<p>Enjoy and thanks!</p>
|
||
<!--
|
||
|
||
Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
|
||
|
||
You are free to share and adapt this file under the terms of this license:
|
||
|
||
Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
|
||
|
||
For more information, see:
|
||
|
||
https://creativecommons.org/licenses/by-sa/4.0/
|
||
|
||
-->
|
||
<!-- AFTER: last line of markdown file: 2001/anonymous/README.md -->
|
||
|
||
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|
||
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|
||
|
||
<!-- START: this line starts content generated by: bin/output-index-inventory.sh -->
|
||
|
||
<div id="inventory">
|
||
<h1 id="inventory-for-2001anonymous">Inventory for 2001/anonymous</h1>
|
||
</div>
|
||
<h2 id="primary-files">Primary files</h2>
|
||
<ul>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.c">anonymous.c</a> - entry source code</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/Makefile">Makefile</a> - entry Makefile</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.orig.c">anonymous.orig.c</a> - original source code</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.bed.c">anonymous.bed.c</a> - Ten In the Bed song C source</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/anonymous.ten.c">anonymous.ten.c</a> - Ten Green Bottles song C source</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/try.sh">try.sh</a> - script to try entry</li>
|
||
</ul>
|
||
<h2 id="secondary-files">Secondary files</h2>
|
||
<ul>
|
||
<li><a href="2001_anonymous.tar.bz2">2001_anonymous.tar.bz2</a> - download entry tarball</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/README.md">README.md</a> - markdown source for this web page</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/.entry.json">.entry.json</a> - entry summary and manifest in JSON</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/.gitignore">.gitignore</a> - list of files that should not be committed under git</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2001/anonymous/.path">.path</a> - directory path from top level directory</li>
|
||
<li><a href="index.html">index.html</a> - this web page</li>
|
||
</ul>
|
||
<hr style="width:10%;text-align:left;margin-left:0">
|
||
<h4>
|
||
Jump to: <a href="#">top</a>
|
||
</h4>
|
||
|
||
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|
||
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|
||
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|
||
|
||
</div>
|
||
|
||
<!-- END: this line ends content from: inc/after-content.default.html -->
|
||
<!-- START: this line starts content from: inc/footer.inventory.html -->
|
||
|
||
<!--
|
||
|
||
Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
|
||
|
||
You are free to share and adapt this file under the terms of this license:
|
||
|
||
Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
|
||
|
||
For more information, see:
|
||
|
||
https://creativecommons.org/licenses/by-sa/4.0/
|
||
|
||
-->
|
||
|
||
<div class="footer">
|
||
|
||
<div id="copyright"><h3>Copyright © 1984-2024 by Landon Curt Noll:
|
||
<a href="https://creativecommons.org/faq/#what-does-some-rights-reserved-mean"
|
||
target="_blank"
|
||
rel="license noopener noreferrer">Some Rights Reserved</a></h3>
|
||
<p>
|
||
This work is <b>licensed by Landon Curt Noll</b> under
|
||
<b><a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1"
|
||
target="_blank"
|
||
rel="license noopener noreferrer"
|
||
style="display:inline-block;">CC BY-SA 4.0</a></b>.
|
||
<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
|
||
src="../../png/cc.png"
|
||
alt="cc inside circle symbol">
|
||
<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
|
||
src="../../png/by.png"
|
||
alt="person inside circle symbol">
|
||
<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
|
||
src="../../png/sa.png"
|
||
alt="arrow looping back on itself inside circle symbol"><br>
|
||
You should <b>carefully review</b> the
|
||
<b><a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en"
|
||
target="_blank"
|
||
rel="license noopener noreferrer">CC BY-SA 4.0 LEGAL CODE</a></b>
|
||
before using the licensed material.<br>
|
||
You may wish to review the
|
||
<b><a href="../../license.html"
|
||
target="_blank"
|
||
rel="license noopener noreferrer">highlights of some of the key features and terms</a></b>
|
||
of <b>CC BY-SA 4.0</b>.<br>
|
||
</p>
|
||
</div>
|
||
|
||
<div id="coda"><h3>Coda</h3>
|
||
<p>
|
||
<a href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fioccc-src.github.io%2Ftemp-test-ioccc%2F2001%2Fanonymous%2Findex.html" rel="nofollow">Nu HTML check this web page</a><br>
|
||
<a href="#top">Jump to top</a> <a href="#content">Jump to Content</a> <a href="#inventory">Jump to Inventory</a><br>
|
||
</p>
|
||
</div>
|
||
|
||
</div>
|
||
|
||
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||
|
||
</body>
|
||
</html>
|
||
|
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