From 5ee593d632ddc9f1ab0a5b407820c153364419eb Mon Sep 17 00:00:00 2001 From: Cody Boone Ferguson <53008573+xexyl@users.noreply.github.com> Date: Mon, 4 Dec 2023 12:48:00 -0800 Subject: [PATCH] Format/typo check 2014/skeggs This includes updating the run of iocccsize -i on the README.md file as the size has changed (it also referred to REMARKS.md but I changed it to README.md). This is to make things consistent. --- 2014/skeggs/README.md | 47 +++++++++++++++++++++---------------------- 1 file changed, 23 insertions(+), 24 deletions(-) diff --git a/2014/skeggs/README.md b/2014/skeggs/README.md index e77b14b97..c971fcf09 100644 --- a/2014/skeggs/README.md +++ b/2014/skeggs/README.md @@ -11,13 +11,6 @@ make ./prog ``` - -### Try: - -```sh -echo "Do or do not. There is no try." -``` - HINT: Try pressing the left and right arrow keys as needed. Also try pressing space/enter to select options. Pressing Q or Escape may end the fun before you are ready. :-) @@ -32,10 +25,10 @@ Look at some of the C pre-processor macros in the source code. Ask yourself why C source is being passed as arguments to some of those macros. -Now you may observe, while it is running, that some C source code -is being written to a file and then compiled. And yet that compiled -code is somehow executed from main. But how? How is main able to -call code that was written and compiled just in time for execution? +Now you may observe, while it is running, that some C source code is being +written to a file and then compiled. And yet that compiled code is somehow +executed from `main()`. But how? How is `main()` able to call code that was +written and compiled just in time for execution? ## Author's remarks: @@ -62,11 +55,12 @@ Armed with your right-facing curly brace, you charge into battle. (Use left and right arrow keys and space/enter to select options. Press Q or Escape to quit.) + ### KNOWN COMPILER WARNINGS Unfortunately, it became very difficult to get this entry to fit within the -size requirements. It's currently at 2052 according to iocccsize, and 3994 -according to wc -c. +size requirements. It's currently at 2052 according to +[iocccsize](../iocccsize.c), and 3994 according to `wc -c`. The current size is a third to a half of the original size before compression. @@ -74,7 +68,7 @@ Due to this, it does LOTS of things that subtly annoy compilers! * (10) data argument not used by format string - This occurs because some of the fprintf invocations don't use all their + This occurs because some of the `fprintf(3)` invocations don't use all their parameters. The program should still work fine! * (1) using the result of an assignment as a condition without parentheses @@ -89,13 +83,14 @@ Due to this, it does LOTS of things that subtly annoy compilers! * (1) control may reach end of non-void function - Turns out that sometimes, a return statement is too much. This will never + Turns out that sometimes, a `return` statement is too much. This will never actually occur, but some C compilers think they know more about my program than I do! :P * (?) Under some systems, `-fPIC` is irrelevant for shared libraries. If so, you should remove it from the Makefile. + ## OBFUSCATION? WHAT OBFUSCATION? THIS IS A PERFECTLY NORMAL C PROGRAM! # THE COOL PART @@ -108,13 +103,13 @@ as would be cool. Essentially, it generates C code at runtime, dumps it to a file, and then runs a C compiler on that file, telling the C compiler to generate a shared library. -Then it loads the shared library with dlopen, and... +Then it loads the shared library with `dlopen(3)`, and... Ignores the result? That can't be right. -Well, it is. Instead of using dlsym like a normal programmer, I mark one of the +Well, it is. Instead of using `dlsym(3)` like a normal programmer, I mark one of the generated functions with `__attribute__((constructor))`. This means that it gets called immediately on load, so it can make its functions available. @@ -126,6 +121,7 @@ then casts to pointers and accesses! It uses this to make certain functions available to the main program, so the main program's generated code will then enter itself where it's needed. + # THE NOT-SO-COOL PART There are also lots of `#defines`. @@ -133,10 +129,10 @@ There are also lots of `#defines`. No, these are not obfuscation. These are compression. There is a little bit of obfuscation gained from using the stringification -operator. (I can never remember what it's actually called, but it's the # +operator. (I can never remember what it's actually called, but it's the `#` operator in a preprocessor macro) - this allows me to pass C code in arguments to the macros, meaning that it gets interpreted as C code instead of a string -by the iocccsize tool, so it gets counted as smaller! :D +by the [iocccsize](../iocccsize.c) tool, so it gets counted as smaller! :D # A SLIGHTLY COOL PART @@ -144,6 +140,7 @@ As part of the JIT compiling, the program hides the fact that it needs ncurses: it just links ncurses with one of the generated shared libraries, and then can access the contents of the ncurses library! + # WAIT WHAT Also, note where functions start and end... @@ -162,11 +159,13 @@ one! (There's an obvious way around this but I'm not going to spell it out for you. That'd be too easy!) + ### MISCELLANEOUS STUFF Do note that there are some other miscellaneous obfuscations, but they should be easy to understand once you figure out the ones above. + ### TROUBLESHOOTING GUIDE This program is a very easy program to cause to fail! @@ -183,7 +182,7 @@ Some things to check (I had to do this under Cygwin.) * Does your system need `-fPIC` (or other arcane invocations) to compile a - shared library? If so, make sure that you include it in the -DCC argument in + shared library? If so, make sure that you include it in the `-DCC` argument in the build script. * Does your system have a vague dislike for `-fPIC`? (Like Cygwin.) You might need to remove it from the build script. @@ -218,11 +217,11 @@ I ran out of time to test it on more systems. Station 13. I didn't, however, look at the minigame at all during the development of this entry. -* What's the length of this REMARKS file according to the iocccsize tool? +* What's the length of this README file according to the +[iocccsize](../iocccsize.c) tool? - `$ ./iocccsize -i