gistfile1.txt

int main() {
    unsigned char *target = mmap(NULL, 1024, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
    Buffer buffer = {target, 1024, 0};
    char *param = "Hello World\n";
    void (*fn)(char*) = (void(*)(char*)) printf;
    append_x86_64_push_reg(&buffer, X86_64_RBP);
    append_x86_64_set_reg_reg(&buffer, X86_64_RBP, X86_64_RSP);
    append_x86_64_set_reg_imm(&buffer, X86_64_RDI, (size_t) param);
    append_x86_64_set_reg_imm(&buffer, X86_64_RAX, (size_t) fn);
    append_x86_64_call_reg(&buffer, X86_64_RAX);
    append_x86_64_pop_reg(&buffer, X86_64_RBP);
    append_x86_64_ret(&buffer);
    for (int i = 0; i < buffer.offset; i += 8) {
        for (int k = i; k < ((i + 8 < buffer.offset) ? (i + 8) : buffer.offset); k++) {
            printf("%02x ", buffer.data[k]);
        }
        printf("\n");
    }
    mprotect(buffer.data, buffer.length, PROT_EXEC);
    union pedantic_convert generated_fn;
    generated_fn.ptr = buffer.data;
    generated_fn.funcptr();
    return 0;
}