A Tiny Arena (Own Once, Free Once)

Implement a bump allocator (arena) — one ownership boundary for many small allocations: ``c typedef struct { unsigned char *buf; size_t cap, used; } Arena; /* in boilerplate */ int arena_init(Arena *a, size_t cap); /* malloc cap bytes; 0 on failure */ /* returns cap bytes of zeroed space inside the arena, or NULL if full */ void *arena_alloc(Arena *a, size_t n); /* frees the whole arena in one free; zeroes the struct */ void arena_destroy(Arena *a); ``

Difficulty: intermediate