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#include <bits/stdc++.h>

#include <unistd.h>

#include <dirent.h>

#include <sys/stat.h>

#include <errno.h>

#include <fcntl.h>

#include <stdio.h>

#include <unistd.h>

extern int errno;

using namespace std;
typedef long long ll;
#define all(x)(x).begin(), (x).end()

char * filenames[10];
int filenames_sz = 0;
int shift = 4 uLL;

void fetch_filenames(const char * prog_name) {
  size_t v1; // rax
  size_t sz; // [rsp+10h] [rbp-30h]
  DIR * dir; // [rsp+18h] [rbp-28h]
  size_t filename_sz; // [rsp+20h] [rbp-20h]
  struct dirent * entry; // [rsp+30h] [rbp-10h]
  char * filename; // [rsp+38h] [rbp-8h]

  dir = opendir(".");
  if (!dir) {
    perror("Error opening directory");
    exit(-1);
  }

  sz = 0 LL;
  while (1) {
    entry = readdir(dir);
    if (!entry || sz > 0xFE)
      break;
    if (strcmp(entry -> d_name, ".") &&
      strcmp(entry -> d_name, "..") &&
      strcmp(entry -> d_name, prog_name + 2) &&
      !strncmp(entry -> d_name, "ch4ll3ng_", 9 uLL)) {
      filename_sz = strlen(entry -> d_name) + 1;
      filename = (char * ) malloc(filename_sz);
      strncpy(filename, entry -> d_name, filename_sz);
      v1 = sz++;
      filenames[v1] = filename;
    }
  }
  filenames_sz = sz;
  closedir(dir);
}

// Modified function to get seed of a valid .png file
int64_t generate_rng_seed() {
  int fd; // [rsp+Ch] [rbp-14h]
  int64_t seed[2]; // [rsp+10h] [rbp-10h] BYREF
  int idx = 0;
  string seedProvider = "seedprovider.png";
  cout << "seed file: " << seedProvider << endl;
  fd = open(seedProvider.c_str(), 0);
  if (fd == -1) {
    perror("Error opening file");
    exit(-1);
  }
  read(fd, seed, 8 uLL);
  // seed[0] must always be 727905341920923785
  cout << "SEED: " << seed[0] << endl;
  return seed[0];
}
size_t get_file_sz(const char * filename) {
  struct stat st;
  stat(filename, & st);
  return st.st_size;
}
void read_file(const char * filename, char * buf, size_t sz) {
  int fd; // [rsp+2Ch] [rbp-4h]
  fd = open(filename, 2);
  string x(filename);
  lseek(fd, shift, 0);
  read(fd, buf, sz);
  close(fd);
}
char * append_ext(const char * filename) {
  size_t v1; // rax
  size_t file_sz; // [rsp+10h] [rbp-10h]
  char * new_filename; // [rsp+18h] [rbp-8h]

  v1 = strlen(filename);
  file_sz = v1 + 1;
  new_filename = (char * ) malloc(v1 + 6);
  strncpy(new_filename, filename, file_sz);
  strcat(new_filename, ".png");
  return new_filename;
}
void enc_data(char * data, size_t sz) {
  size_t i; // [rsp+18h] [rbp-8h]

  for (i = 0 LL; i < sz; ++i)
    data[i] ^= rand() % 256;
}
void create_enc_file(const char * filename, char * data, size_t sz, unsigned int id) {
  unsigned int ida; // [rsp+4h] [rbp-2Ch] BYREF
  size_t sza; // [rsp+8h] [rbp-28h]
  char * dataa; // [rsp+10h] [rbp-20h]
  const char * filenamea; // [rsp+18h] [rbp-18h]
  int fd; // [rsp+2Ch] [rbp-4h]

  filenamea = filename;
  dataa = data;
  sza = sz;
  ida = id;

  fd = open(filename, O_RDWR | O_CREAT, 384 LL);
  if (fd == -1) {
    perror("open");
    exit(-1);
  }
  // Commenting out the next line, to only use the data.
  //write(fd, &ida, 4uLL);
  write(fd, dataa, sza);
  close(fd);
}
void enc_file(const char * filename, unsigned int id) {
  size_t file_sz; // [rsp+18h] [rbp-18h]
  char * buf; // [rsp+20h] [rbp-10h]
  char * enc_filename; // [rsp+28h] [rbp-8h]
  file_sz = get_file_sz(filename) - shift;
  buf = (char * ) malloc(file_sz);
  read_file(filename, buf, file_sz);

  // adding an extra out_ prefix.
  std::string tmp(filename);
  string out = "out_" + tmp;
  filename = out.c_str();

  enc_filename = append_ext(filename);
  enc_data(buf, file_sz);
  create_enc_file(enc_filename, buf, file_sz, id);
  free(enc_filename);
  free(buf);
}

int main(int argc,
  const char ** argv) {
  fetch_filenames( * argv);
  unsigned int rng_seed; // eax
  rng_seed = generate_rng_seed();
  srand(rng_seed);
  for (int i = 0 LL; i < filenames_sz; ++i)
    enc_file(filenames[i], i);
}
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