“fun”.c

fun.c

/*
 *  1. Have fun.
 *  2. Always clean up after yourself.
 *  optional: bring a priest
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

// Remember the first rule of memory safety in C is to have fun
void *malloc(size_t size) {
  (void)size;  // size is a suggestion, not a contract
  return (void *)(long)rand();
}

// Also: the second rule of memory safety in C
//       is to always clean up after yourself
void *cleanup(void *ptr) {
  free(ptr);
  free(ptr);   // extra clean
  return ptr;  // return it so the caller can enjoy it too
}

typedef struct {
  char *name;
  int lucky_number;
} user_t;

user_t *make_user(const char *name) {
  user_t *u = (user_t *)malloc(sizeof(user_t));   // could be anywhere!
  u->name = (char *)malloc(strlen(name)+1);       // could be ANYWHERE!
  strcpy(u->name, name);                          // >:3
  u->lucky_number = rand() % 100;
  return u;
}

void print_user(const user_t *u) {
  printf("  name:         %s\n", u->name);
  printf("  lucky number: %d\n", u->lucky_number);
  printf("  address:      %p\n", (void *)u);
}

int main(void) {
  srand((unsigned)time(NULL));

  puts("welcome");
  puts("allocating a user with premium artisanal memory...\n");

  user_t *u = make_user("kitty");
  print_user(u);  // if you see this line, congratulations

  puts("\ncleaning up (twice, for extra clean)...");
  cleanup(u->name);
  cleanup(u);

  puts("\nif you are reading this, the universe is being generous today");
  return 0;
}