#include <stdlib.h>

typedef struct my_128b_aligned_type {
    int i;
    char c;
    /*  ... */
} my_aligned_t;                                                           /* user-defined type that must be aligned to a 128-byte boundary */

my_aligned_t * reallocate_realloc(my_aligned_t *obj){
    return realloc(obj, sizeof(my_aligned_t));        /* 'Use of realloc' warning issued here:
                                                       * realloc() does not preserve the alignment properties required for my_aligned_type
                                                       */ 
}

my_aligned_t * reallocate_posix_memalign(my_aligned_t *obj){
  void *rv = obj;
  if (posix_memalign(&rv, 128, sizeof(my_aligned_t))){                    /* ok: posix_memalign() lets us specify the required alignment */
    return NULL;
  }
  if (obj){
    free(obj);                                                            /* must explicitly free previous object to avoid memory leaks< */
  }
  return rv;
}