[3.6] bpo-31786: Make functions in the select module blocking when timeout is a small negative value. (GH-4003). (#4022)

(cherry picked from commit 2c15b29aea5d6b9c61aa42d2c24a07ff1edb4b46)

1 files changed, 12 insertions, 1 deletions

diff --git a/Include/pytime.h b/Include/pytime.h
index 87ac7fc..9e1f304 100644
--- a/Include/pytime.h
+++ b/Include/pytime.h
@@ -29,9 +29,20 @@ typedef enum {
     _PyTime_ROUND_CEILING=1,
     /* Round to nearest with ties going to nearest even integer.
        For example, used to round from a Python float. */
-    _PyTime_ROUND_HALF_EVEN
+    _PyTime_ROUND_HALF_EVEN=2,
+    /* Round away from zero 
+       For example, used for timeout. _PyTime_ROUND_CEILING rounds
+       -1e-9 to 0 milliseconds which causes bpo-31786 issue.
+       _PyTime_ROUND_UP rounds -1e-9 to -1 millisecond which keeps
+       the timeout sign as expected. select.poll(timeout) must block
+       for negative values." */
+    _PyTime_ROUND_UP=3,
+    /* _PyTime_ROUND_TIMEOUT (an alias for _PyTime_ROUND_UP) should be 
+       used for timeouts. */
+    _PyTime_ROUND_TIMEOUT = _PyTime_ROUND_UP
 } _PyTime_round_t;
 
+
 /* Convert a time_t to a PyLong. */
 PyAPI_FUNC(PyObject *) _PyLong_FromTime_t(
     time_t sec);