Funtoo binfmt misc Qemu chroot Guide

Funtoo binfmt_misc Qemu chroot Guide: aka (Frankenroot)

   qemu-arm.c (C source code) - qemu arm wrapper

/*
     * Call QEMU binary with additional "-cpu cortex-a53" argument.
     *
     * Copyright (c) 2018 sakaki <sakaki@deciban.com>
     * License: GPL v3.0+
     *
     * Based on code from the Gentoo Embedded Handbook
     * ("General/Compiling_with_qemu_user_chroot")
     */

    #include <string.h>
    #include <unistd.h>

    int main(int argc, char **argv, char **envp) {
        char *newargv[argc + 3];

        newargv[0] = argv[0];
        newargv[1] = "-cpu";
        newargv[2] = "cortex-a7";

        memcpy(&newargv[3], &argv[1], sizeof(*argv) * (argc -1));
        newargv[argc + 2] = NULL;
        return execve("/usr/local/bin/qemu-arm", newargv, envp);
    }

   masky.py (python source code) - masky

#!/usr/bin/python3
import sys
import struct
import string
import codecs

printable_chars = set(string.printable)
printable_chars = set()
def print_out_hexstring(hexstring):
    to_process = hexstring
    while len(to_process):
        ascii_value = chr(int(to_process[:2], 16))
        to_process = to_process[2:]
        if ascii_value in printable_chars:
            sys.stdout.write(ascii_value)
        else:
            sys.stdout.write("\\x" + "{0:02x}".format(ord(ascii_value)))


chunk_as_hexstring = ""
with open(sys.argv[1], 'rb') as f:
    for x in range(0,19):
       chunk_as_hexstring += f.read(1).hex()
mask_as_hexstring = "fffffffffffffffcfffffffffffffffffeffff"
mask = int(mask_as_hexstring, 16)
chunk = int(chunk_as_hexstring, 16)
out_as_hexstring = hex(chunk & mask)[2:]
sys.stdout.write(":arm:M::")
print_out_hexstring(out_as_hexstring)
sys.stdout.write(":")
print_out_hexstring(mask_as_hexstring)
sys.stdout.write(":/usr/local/bin/qemu-arm-wrapper:\n")