CCCC - A very special "decompiler"

CCCC is a tool that lets you extract functions as bytecode strings you can then drop into C source files, cast to function, then execute.

The bytecode strings are not made to be pretty, but I could add a flag to make it a little bit prettier. For now, the strings are as compact as they can be.

It follows absolutely no C best practice and is actually pretty rarely useful, rendering your code immediately non-portable and fixed to the architecture your code was originally made for (or whatever assembly you used with -a)

It only works on linux despite being made in python (because it uses tools that are built on that system)

It's just an excuse for me to experiment with compiled binaries, I guess.

Usage

cccc [options] [--] objfile

Here are the various options you can pass to this program :

• -k <symbol,...> : A list of symbols to only keep
• -s <section,...> : A list of sections to only keep
• -t <type> : The type that corresponds to the C string unit
• -a <id> : Dumps the ASM string as a function named id
• -D : Dump all symbols (like objdump's -D)
• -b <id> : Dumps the input C function as a symbol named id
• -f : Append a function definition (for -b or -a) Renames the symbol as id_fn to name the function itself id
• --args <args> : The arguments of the function(s), with the parentheses (for -b and/or -f)
• --returns <type> : The return type of the function(s) (for -b and/or -f)

Adding -- will tell it to stop reading options.

Prerequisites

This tool requires gcc and objdump in your path. If you are using this tool, you probably have them already installed.

Example

This is a way you can use CCCC to drop a bunch of bytecode that will run the exit syscall (linux, x86-64):

__attribute__((section(".text#")))
const char exit_function[16] =
    "UH\x89\xe5H\xc7\xc0<\0\0\0\x0f\x05\x90]\xc3";
const void (*exit2)(volatile register long status) =
    (void(*)(long)) exit_function;

void _start(void)
{
    exit2(0); // This will exit using the provided exit code.
}

(Compile it using gcc -nostdlib <source_file> to get a usable result)

As mentioned, not that useful considering you can use exit(n) in literally any circumstance, and that would be much more portable.

Making of this program

This was made in a random Discord VC at 2AM. Don't expect clean code, or more than a single massive commit. Don't even expect a docstring.

Also, this has nearly no error handling.