commit 80e57af50fe06ac76733ee99644c5efe797b2b8c
Author: Sebastian Hahn <sebastian(a)torproject.org>
Date: Tue Apr 26 03:01:25 2011 +0200
Appease clang - and my tortured mind
This possible div by 0 warning from clang's analyzer was quite fun to
track down. Turns out the current behaviour is safe.
---
src/or/circuitbuild.c | 12 +++++++++++-
1 files changed, 11 insertions(+), 1 deletions(-)
diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c
index 0e033a5..2189e0e 100644
--- a/src/or/circuitbuild.c
+++ b/src/or/circuitbuild.c
@@ -559,7 +559,9 @@ circuit_build_times_create_histogram(circuit_build_times_t *cbt,
* Return the Pareto start-of-curve parameter Xm.
*
* Because we are not a true Pareto curve, we compute this as the
- * weighted average of the N=3 most frequent build time bins.
+ * weighted average of the N most frequent build time bins. N is either
+ * 1 if we don't have enough circuit build time data collected, or
+ * determined by the consensus parameter cbtnummodes (default 3).
*/
static build_time_t
circuit_build_times_get_xm(circuit_build_times_t *cbt)
@@ -572,6 +574,9 @@ circuit_build_times_get_xm(circuit_build_times_t *cbt)
int n=0;
int num_modes = circuit_build_times_default_num_xm_modes();
+ tor_assert(nbins > 0);
+ tor_assert(num_modes > 0);
+
// Only use one mode if < 1000 buildtimes. Not enough data
// for multiple.
if (cbt->total_build_times < CBT_NCIRCUITS_TO_OBSERVE)
@@ -579,6 +584,7 @@ circuit_build_times_get_xm(circuit_build_times_t *cbt)
nth_max_bin = (build_time_t*)tor_malloc_zero(num_modes*sizeof(build_time_t));
+ /* Determine the N most common build times */
for (i = 0; i < nbins; i++) {
if (histogram[i] >= histogram[nth_max_bin[0]]) {
nth_max_bin[0] = i;
@@ -600,6 +606,10 @@ circuit_build_times_get_xm(circuit_build_times_t *cbt)
histogram[nth_max_bin[n]]);
}
+ /* The following assert is safe, because we don't get called when we
+ * haven't observed at least CBT_MIN_MIN_CIRCUITS_TO_OBSERVE circuits. */
+ tor_assert(bin_counts > 0);
+
ret /= bin_counts;
tor_free(histogram);
tor_free(nth_max_bin);