Refactor the tor_calloc_ overflow check.

  return result;

}

#define SQRT_SIZE_MAX (((size_t) SIZE_MAX) >> (sizeof(size_t) * 8 / 2))

static INLINE int

size_mul_check(const size_t x, const size_t y)

{

  return ((x <= SQRT_SIZE_MAX && y <= SQRT_SIZE_MAX) ||

          y == 0 || x <= SIZE_MAX / y);

}

/** Allocate a chunk of <b>nmemb</b>*<b>size</b> bytes of memory, fill

 * the memory with zero bytes, and return a pointer to the result.

 * Log and terminate the process on error.  (Same as

 * calloc(<b>nmemb</b>,<b>size</b>), but never returns NULL.)

 *

 * XXXX This implementation probably asserts in cases where it could

 * work, because it only tries dividing SIZE_MAX by size (according to

 * the calloc(3) man page, the size of an element of the nmemb-element

 * array to be allocated), not by nmemb (which could in theory be

 * smaller than size).  Don't do that then.

 */

void *

tor_calloc_(size_t nmemb, size_t size DMALLOC_PARAMS)

   * we're allocating something very big (it knows if it just got the memory

   * from the OS in a pre-zeroed state).  We don't want to use tor_malloc_zero

   * for big stuff, so we don't bother with calloc. */

  void *result;

  size_t max_nmemb = (size == 0) ? SIZE_MAX : SIZE_MAX/size;

  tor_assert(nmemb < max_nmemb);

  result = tor_malloc_zero_((nmemb * size) DMALLOC_FN_ARGS);

  return result;

  tor_assert(size_mul_check(nmemb, size));

  return tor_malloc_zero_((nmemb * size) DMALLOC_FN_ARGS);

}

/** Change the size of the memory block pointed to by <b>ptr</b> to <b>size</b>