Add early year check to fromisocalendar

This avoids an overflow error in ordinal calculations in the C implementation.
python · vstinner · Apr 29, 2019 · Feb 15, 2019 · Feb 17, 2019 · Feb 17, 2019
commit fbab728dfb75723f8ee57f146dbdc31613270470
diff --git a/Lib/datetime.py b/Lib/datetime.py
@@ -886,6 +886,10 @@ def fromisoformat(cls, date_string):
 
     @classmethod
     def fromisocalendar(cls, year, week, day):
+        # Year is bounded this way because 9999-12-31 is (9999, 52, 5)
+        if not 0 < year < 10000:
+            raise ValueError(f"Year is out of range: {year}")
+
         if not 0 < week < 54:
             raise ValueError(f"Invalid week: {week}")
 

diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
@@ -1826,6 +1826,9 @@ class KnownFailure(tuple):
             (2019, 1, -1),
             (2019, 1, 8),
             KnownFailure([2019, 53, 1]),
+            (10000, 1, 1),
+            (0, 1, 1),
+            (9999999, 1, 1),
         ]
 
         for isocal in isocals:
@@ -1842,9 +1845,6 @@ class KnownFailure(tuple):
                     raise Exception("XPASS: Known failure condition not met")
 
 
-
-
-
 #############################################################################
 # datetime tests
 

diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
@@ -3028,6 +3028,12 @@ date_fromisocalendar(PyObject *cls, PyObject *args, PyObject *kw) {
         return NULL;
     }
 
+    // Year is bounded to 0 < year < 10000 because 9999-12-31 is (9999, 52, 5)
+    if (year <= 0 || year >= 10000) {
+        PyErr_Format(PyExc_ValueError, "Year is out of range: %d", year);
+        return NULL;
+    }
+
     if (week <= 0 || week >= 54) {
         PyErr_Format(PyExc_ValueError, "Invalid week: %d", week);
         return NULL;
@@ -3038,6 +3044,7 @@ date_fromisocalendar(PyObject *cls, PyObject *args, PyObject *kw) {
         return NULL;
     }

+
     int month = week;
     isocalendar_to_ymd(&year, &month, &day);