bpo-31786: Make functions in the select module blocking when timeout is a small negative value. (#4003)

1 files changed, 15 insertions, 2 deletions

diff --git a/Python/pytime.c b/Python/pytime.c
index 7b55b10d10..f19bb3673e 100644
--- a/Python/pytime.c
+++ b/Python/pytime.c
@@ -120,9 +120,13 @@ _PyTime_Round(double x, _PyTime_round_t round)
     else if (round == _PyTime_ROUND_CEILING) {
         d = ceil(d);
     }
-    else {
+    else if (round == _PyTime_ROUND_FLOOR) {
         d = floor(d);
     }
+    else {
+        assert(round == _PyTime_ROUND_UP);
+        d = (d >= 0.0) ? ceil(d) : floor(d);
+    }
     return d;
 }
 
@@ -427,7 +431,7 @@ _PyTime_Divide(const _PyTime_t t, const _PyTime_t k,
             return t / k;
         }
     }
-    else {
+    else if (round == _PyTime_ROUND_FLOOR){
         if (t >= 0) {
             return t / k;
         }
@@ -435,6 +439,15 @@ _PyTime_Divide(const _PyTime_t t, const _PyTime_t k,
             return (t - (k - 1)) / k;
         }
     }
+    else {
+        assert(round == _PyTime_ROUND_UP);
+        if (t >= 0) {
+            return (t + k - 1) / k;
+        }
+        else {
+            return (t - (k - 1)) / k;
+        }
+    }
 }
 
 _PyTime_t