Bug 975996: Add _PyTime_DoubleToTimet to C API

New include file timefuncs.h exports private API function
_PyTime_DoubleToTimet() from timemodule.c.  timemodule should export
some other functions too (look for painful bits in datetimemodule.c).

Added insane-argument checking to datetime's assorted fromtimestamp()
and utcfromtimestamp() methods.  Added insane-argument tests of these
to test_datetime, and insane-argument tests for ctime(), localtime()
and gmtime() to test_time.

2 files changed, 20 insertions, 12 deletions

diff --git a/Modules/datetimemodule.c b/Modules/datetimemodule.c
index 7f38d1a..d9cf604 100644
--- a/Modules/datetimemodule.c
+++ b/Modules/datetimemodule.c
@@ -8,6 +8,7 @@
 
 #include <time.h>
 
+#include "timefuncs.h"
 #include "datetime.h"
 
 /* We require that C int be at least 32 bits, and use int virtually
@@ -2226,11 +2227,15 @@ date_new(PyTypeObject *type, PyObject *args, PyObject *kw)
 
 /* Return new date from localtime(t). */
 static PyObject *
-date_local_from_time_t(PyObject *cls, time_t t)
+date_local_from_time_t(PyObject *cls, double ts)
 {
 	struct tm *tm;
+	time_t t;
 	PyObject *result = NULL;
 
+	t = _PyTime_DoubleToTimet(ts);
+	if (t == (time_t)-1 && PyErr_Occurred())
+		return NULL;
 	tm = localtime(&t);
 	if (tm)
 		result = PyObject_CallFunction(cls, "iii",
@@ -2278,7 +2283,7 @@ date_fromtimestamp(PyObject *cls, PyObject *args)
 	PyObject *result = NULL;
 
 	if (PyArg_ParseTuple(args, "d:fromtimestamp", &timestamp))
-		result = date_local_from_time_t(cls, (time_t)timestamp);
+		result = date_local_from_time_t(cls, timestamp);
 	return result;
 }
 
@@ -3654,10 +3659,15 @@ static PyObject *
 datetime_from_timestamp(PyObject *cls, TM_FUNC f, double timestamp,
 			PyObject *tzinfo)
 {
-	time_t timet = (time_t)timestamp;
-	double fraction = timestamp - (double)timet;
-	int us = (int)round_to_long(fraction * 1e6);
+	time_t timet;
+	double fraction;
+	int us;
 
+	timet = _PyTime_DoubleToTimet(timestamp);
+	if (timet == (time_t)-1 && PyErr_Occurred())
+		return NULL;
+	fraction = timestamp - (double)timet;
+	us = (int)round_to_long(fraction * 1e6);
 	return datetime_from_timet_and_us(cls, f, timet, us, tzinfo);
 }
 
diff --git a/Modules/timemodule.c b/Modules/timemodule.c
index 0783f7f..f855796 100644
--- a/Modules/timemodule.c
+++ b/Modules/timemodule.c
@@ -3,6 +3,7 @@
 
 #include "Python.h"
 #include "structseq.h"
+#include "timefuncs.h"
 
 #include <ctype.h>
 
@@ -84,11 +85,8 @@ static double floattime(void);
 /* For Y2K check */
 static PyObject *moddict;
 
-/* Cast double x to time_t, but raise ValueError if x is too large
- * to fit in a time_t.  ValueError is set on return iff the return
- * value is (time_t)-1 and PyErr_Occurred().
- */
-static time_t
+/* Exposed in timefuncs.h. */
+time_t
 _PyTime_DoubleToTimet(double x)
 {
 	time_t result;
@@ -382,7 +380,7 @@ time_strftime(PyObject *self, PyObject *args)
         /* Checks added to make sure strftime() does not crash Python by
             indexing blindly into some array for a textual representation
             by some bad index (fixes bug #897625).
-        
+
             No check for year since handled in gettmarg().
         */
         if (buf.tm_mon < 0 || buf.tm_mon > 11) {
@@ -583,7 +581,7 @@ time_tzset(PyObject *self, PyObject *args)
 	/* Reset timezone, altzone, daylight and tzname */
 	inittimezone(m);
 	Py_DECREF(m);
-	
+
 	Py_INCREF(Py_None);
 	return Py_None;
 }