Use a time-invariant comparison in choose_array_element_by_weight

#undef SCALE_TO_U64_MAX

}

/** Time-invariant 64-bit greater-than; works on two integers in the range

 * (0,INT64_MAX). */

#if SIZEOF_VOID_P == 8

#define gt_i64_timei(a,b) ((a) > (b))

#else

static INLINE int

gt_i64_timei(uint64_t a, uint64_t b)

{

  int64_t diff = (int64_t) (b - a);

  int res = diff >> 63;

  return res & 1;

}

#endif

/** Pick a random element of <b>n_entries</b>-element array <b>entries</b>,

 * choosing each element with a probability proportional to its (uint64_t)

 * value, and return the index of that element.  If all elements are 0, choose

  if (total == 0)

    return crypto_rand_int(n_entries);

  tor_assert(total < INT64_MAX);

  rand_val = crypto_rand_uint64(total);

  for (i = 0; i < n_entries; ++i) {

    total_so_far += entries[i].u64;

    if (total_so_far > rand_val) {

    if (gt_i64_timei(total_so_far, rand_val)) {

      i_chosen = i;

      n_chosen++;

      /* Set rand_val to UINT_MAX rather than stopping the loop. This way,

      /* Set rand_val to INT64_MAX rather than stopping the loop. This way,

       * the time we spend in the loop does not leak which element we chose. */

      rand_val = UINT64_MAX;

      rand_val = INT64_MAX;

    }

  }

  tor_assert(total_so_far == total);