commit 80e57af50fe06ac76733ee99644c5efe797b2b8c Author: Sebastian Hahn sebastian@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);