#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <unistd.h>

#define CHECK(result, textOnFail)                                              \
  if (((long int)result) == -1) {                                              \
    perror(textOnFail);                                                        \
    exit(1);                                                                   \
  }

struct myData {
  int version;
  char text[1020];
};

volatile sig_atomic_t stopFlag = 0;
void ctrlC(int num) { stopFlag = 1; }

int main() {
  int fd = shm_open("/os_cp", O_RDWR | O_CREAT, 0600);
  CHECK(fd, "shm_open failed");
  int r = ftruncate(fd, sizeof(struct myData));
  CHECK(r, "ftruncate failed");
  struct myData *data = mmap(NULL, sizeof(struct myData),
                             PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  CHECK(data, "mmap failed");
  close(fd);

  signal(SIGINT, ctrlC);
  while (!stopFlag) {
    for (char letter = 'a'; letter <= 'z'; ++letter) {
      data->version++;
      for (int i = 0; i < 1020 - 1; ++i) {
        data->text[i] = letter;
      }
      if (stopFlag)
        break;
    }
  }
  munmap(data, sizeof(struct myData));
  return 0;
}