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2001/anonymous updates

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Format fix in README.md.

Add cpp.c which is the C pre-processed version cleaned up and somewhat
commented as it heavily (ab)uses the ternary operator and recursion.
Probably futile but it gave me something to do even if it was a waste of
time (could have worked on other README.md files or a host of other
things). This did indeed take a long time and a lot of effort!

Updated bugs.md with more hints about this entry. I explained here how I
came up with the C pre-processed version as it involves something of a
hack because of the complicated build instructions.

Updated anonymous.ten.c: #include <stdio.h>

Added anonymous.ten rule to Makefile.

Also disabled optimising level as the author stated that this makes it
slower.

I observed that the author is anonymous and yet the author information
shows the country. I'm not sure if this is intended or not.
This commit is contained in:
Cody Boone Ferguson committed 2023-04-21 05:46:10 -07:00
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2001/anonymous/README.md
+61 -56
View File
@@ -1,7 +1,7 @@
# Most likely to amaze
The author wishes to remain anonymous
Great Britain
The author wishes to remain anonymous
Great Britain
## To build:
@@ -15,17 +15,21 @@ make
./anonymous program
```
NOTE: this entry seems to no longer work. [Cody Boone
Ferguson](/winners.html#Cody_Boone_Ferguson) has offered some tips in the
NOTE: [Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed the
supplementary program which is necessary to test the program. He C pre-processed
and cleaned it up as well as commented it some as it heavily uses the ternary
operator and recursive calls. It is not consistent but if you look at it you
should understand why that is! Thank you Cody for your assistance! He notes
however that this entry seems to no longer work and has offered some tips in the
[bugs.md](/bugs.md) file for anyone who mights want to try and fix this but it
seems to require a lot of parsing, debugging, an x86 system and possibly knowing
the internals of the ELF format (x86 specific). You need to run the program on a
binary to test. See the try section below for a program that, if you get the
entry to work, would be okay to test it on. Thank you and we will happily credit
you if you fix this.
does seem to require a lot of parsing, debugging, an x86 system and possibly
knowing the internals of the ELF format (x86 specific if there are any?). You
need to run the program on a binary to test. See the try section below for the
above mentioned program that you can test the entry on. Thank you and we will
happily credit you if you fix this.
WARNING: if you do get this to work it will destroy files that it is used on.
See the author's warning on this.
WARNING: if you do get this to work **IT WILL _DESTROY FILES__ that it is used
on!** See the author's warning on this.
## Try:
@@ -46,7 +50,8 @@ quite a lot of bit twiddling.
This program is an optimizing dynamic binary translator, allowing you to
run x86 programs on any machine (x86 or otherwise).
I have included a simple "10 green bottles" program, already compiled
I have included a simple [10 green
bottles](https://www.bbc.co.uk/teach/school-radio/nursery-rhymes-ten-green-bottles/zncyt39) program, already compiled
for the x86. The program 'ten', and its source (dull) are given as info
files. Warning: note that the translator screws around with the binary
you run on it, *will* corrupt the binary to some extent, and may leave
@@ -88,75 +93,75 @@ switches such that while compiling the program it generates one error
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 "warning=..." line from the build
script.
your C compiler please remove the `-Dwarning='-Dprocessor'` line and the
`$$warning` from the compiler invocation.
### Optimization:
### Optimization
The build script contains a "-O1" switch for the compiler. Increasing
The build script contains a `-O1` switch for the compiler. Increasing
the optimization level will make the program run *slower*, while
compiling the program without any optimization will allow it to run
*faster*.
### Obfuscation:
### Obfuscation
The most obvious part of the obfuscation is probably the mess of defines
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 "#"
preprocessor operator to turn them into strings. In the hope throwing 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.
The most obvious part of the obfuscation is probably the mess of defines 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 `#` 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.
Buried under all this, and the fact that the entire program is just a
call to exit, there are some nice subtle little obfuscations. For
call to `exit()`, there are some nice subtle little obfuscations. For
example, you may notice that there are a couple of macros that use the
"##" preprocessor operator to build pairs of functions. One of these
`##` preprocessor operator to build pairs of functions. One of these
macros is used to build to 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.
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 PC to point at main, etc) gets turned into a
frog^M^M^M^Mstring. 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.
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
[PC / IP](https://en.wikipedia.org/wiki/Program_counter) to point at `main()`,
etc) gets turned into a `frog^M^M^M^Mstring`. 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.
### Limitations:
### Limitations
Due to space limitations only a handful of instructions are supported,
those instructions which are supported may supported in somewhat
non-conventional ways, chunks of the architecture (e.g. flags) are just
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 loader does not really load the elf binary, the target
library linking can only pass up to 3 parameters to the target library
function, etc, etc, etc.
function, etc.
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.
Despite all this, the translator is not exclusively limited to running
the 'ten' program. Other trivial x86 programs may run on the translator
\- and I have successfully run a wide range of HelloWorld programs,
including one of last years IOCCC winners, 'tomx'.
Despite all this, the translator is not exclusively limited to running the
[anonymous.ten](anonymous.ten.c) program. Other trivial **_x86_** programs may
run on the translator \- and I have successfully run a wide range of "Hello
World" programs, including one of last years IOCCC winners,
[tomx](/2000/tomx/tomx.c).
### Complete Program:
### Complete Program
The fact that the program makes calls to system and execv may imply that
it is not a complete program in its own right, as it relies on other
programs. The call to system is a call to ask gcc to recompile the
translator with a new set of switches, and the call to execv 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 winners at any rate, and I recognize that a few
don't). There is little real difference between this program and one
like last years entry 'dhyang'; both are just C programs that generate C
code as their output.
The fact that the program makes calls to `system()` and `execv()` may imply that
it is not a complete program in its own right, as it relies on other programs.
The call to `system()` is a call to ask gcc to recompile the translator with a
new set of switches, and the call to `execv()` 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 winners at any rate,
and I recognize that a few don't). There is little real difference between this
program and one like last years entry [dhyang](/2000/dhyang/dhyang.c); both are
just C programs that generate C code as their output.
Enjoy, thanks!
Enjoy and thanks!
## Copyright and CC BY-SA 4.0 License: