#include <errno.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct creds creds_t;

typedef struct creds {
  char name[16];
  void (*welcome)(void);
} creds_t;

static creds_t *creds;

/* internal prototypes */
static void login(void);

static void s3cr3t(void);

/* entry point */
// ./mixed01 aaaaaaaaaaaaaaaaa 65536
int main(int argc, char **argv) {
  if (argc < 3) {
    printf("usage: %s <name> <length of name>\n", argv[0]);
    return -1;
  }
  int32_t size = atoi(argv[2]);
  uint16_t s = size;
  creds = (creds_t *)calloc(1, sizeof(creds_t));
  if (!creds) {
    perror("calloc");
    return -1;
  }
  if (s >= sizeof(creds->name)) {
    fprintf(stderr, "length exceeds buffer size\n");
    free(creds);
    return -1;
  }
  creds->welcome = login;
  snprintf(creds->name, size + 1, "%s", argv[1]);
  creds->welcome();
  free(creds);
  return 0;
}

/* internal function definitions */
static void login(void) { printf("Hello %s.\n", creds->name); }

static void s3cr3t(void) { printf("You've gathered secret material!\n"); }