#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <getopt.h>

int main(int argc, char *argv[]) {
  FILE *input = stdin;
  int buffer_size = 4096;

  // Parse command line arguments
  // -f filename (optional)
  // b buffer_size (optional)
  char opt;
  while ((opt = getopt(argc, argv, "f:b:")) != -1) {
    switch (opt) {
    case 'f':
      input = fopen(optarg, "r");
      if (input == NULL) {
        fprintf(stderr, "Error: Could not open input file\n");
        return EXIT_FAILURE;
      }
      break;
    case 'b':
      buffer_size = atoi(optarg); break;
    default:
      printf("Usage: %s [-f filename] [-b buffer_size]\n", argv[0]);
      return 1;
    }
  }

  // Allocate buffer
  char *buffer = malloc(buffer_size);

  // Read from input and write to stdout
  while (fgets(buffer, buffer_size, input) != NULL) {
    fwrite(buffer, sizeof(char), strlen(buffer), stdout);
  }

  // Cleanup
  free(buffer);

  return 0;
}