#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>
#include <unistd.h>

#define COUNT_FILE "../data/counter.c.txt"

int main(void) {
  int fd;
  FILE *fp;
  int count = 0;

  fd = open(COUNT_FILE, O_RDWR | O_CREAT, 0644);
  if (fd == -1) {
    perror("open");
    return 1;
  }

  if (flock(fd, LOCK_EX) == -1) {
    perror("flock");
    close(fd);
    return 1;
  }

  fp = fdopen(fd, "r+");
  if (fp == NULL) {
    perror("fdopen");
    close(fd);
    return 1;
  }

  if (fscanf(fp, "%d", &count) != 1) {
    count = 0;
  }
  count++;

  rewind(fp);
  fprintf(fp, "%d\n", count);
  /*
  fflush(fp);
  ftruncate(fd, ftell(fp));
  */

  fclose(fp);

  printf("Content-Type: text/plain\n");
  printf("\n");

  printf("%d\n", count);

  return 0;
}