naive.c

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

#define BUFFER_SIZE 8192

size_t process_data(char *text, size_t bytes_read)
{
  size_t popCount = 0;
  while (bytes_read > 0) {
    char *ptr = memchr(text, '\n', bytes_read);
    if (ptr == NULL) {
      return popCount;
    } else {
      popCount++;
      bytes_read = bytes_read - ((ptr - text) + 1);
      text = ptr + 1;
    }
  }
}

int main(int argc, char **argv)
{
  if (argc < 2) {
    return 1;
  }

  char *in_filename = argv[1];

  FILE *in_file = fopen(in_filename,  "r");

  if (!in_file) {
    return 1;
  }

  char buffer[BUFFER_SIZE];

  size_t total_bytes_read = 0;

  size_t bytes_read = fread(buffer, 1, BUFFER_SIZE, in_file);

  size_t newline_count = 0;

  while (bytes_read > 0) {
    total_bytes_read += bytes_read;

    newline_count += process_data(buffer, bytes_read);

    bytes_read = fread(buffer, 1, BUFFER_SIZE, in_file);
  }

  printf("%zu\n", newline_count);

  fclose(in_file);

  return 0;

}