[tor-commits] [tor/maint-0.2.8] Avoid errors in updateFallbackDirs.py when there are no fallbacks

[nickm at torproject.org]

commit 40906122469e3be5421778ceded665fde40868d9
Author: teor (Tim Wilson-Brown) <teor2345 at gmail.com>
Date:   Wed Jun 22 11:04:54 2016 +1000

    Avoid errors in updateFallbackDirs.py when there are no fallbacks
---
 scripts/maint/updateFallbackDirs.py | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/scripts/maint/updateFallbackDirs.py b/scripts/maint/updateFallbackDirs.py
index 7fcb365..d17e702 100755
--- a/scripts/maint/updateFallbackDirs.py
+++ b/scripts/maint/updateFallbackDirs.py
@@ -1408,7 +1408,11 @@ class CandidateList(dict):
   def calculate_measured_bandwidth(self):
     self.sort_fallbacks_by_cw_to_bw_factor()
     median_fallback = self.fallback_median(True)
-    median_cw_to_bw_factor = median_fallback.cw_to_bw_factor()
+    if median_fallback is not None:
+      median_cw_to_bw_factor = median_fallback.cw_to_bw_factor()
+    else:
+      # this will never be used, because there are no fallbacks
+      median_cw_to_bw_factor = None
     for f in self.fallbacks:
       f.set_measured_bandwidth(median_cw_to_bw_factor)
 
@@ -1593,7 +1597,11 @@ class CandidateList(dict):
   # return a string that describes a/b as a percentage
   @staticmethod
   def describe_percentage(a, b):
-    return '%d/%d = %.0f%%'%(a, b, (a*100.0)/b)
+    if b != 0:
+      return '%d/%d = %.0f%%'%(a, b, (a*100.0)/b)
+    else:
+      # technically, 0/0 is undefined, but 0.0% is a sensible result
+      return '%d/%d = %.0f%%'%(a, b, 0.0)
 
   # return a dictionary of lists of fallbacks by IPv4 netblock
   # the dictionary is keyed by the fingerprint of an arbitrary fallback