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gh-103648: Make datetime.timestamp() raise OverflowError when overflow on Windows #103653

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gh-103648: Make datetime.timestamp() raise OverflowError when overflow on Windows #103653

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0de68d4
Make timestamp() raise overflowerror on overflow
gaogaotiantian Apr 20, 2023
49ca04f
📜🤖 Added by blurb_it.
blurb-it[bot] Apr 20, 2023
8c063af
Add the assertion for tm != NULL
gaogaotiantian Jun 9, 2023
10653f0
Update comments
gaogaotiantian Jun 9, 2023
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5 changes: 5 additions & 0 deletions Lib/test/datetimetester.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2481,6 +2481,11 @@ def test_timestamp_aware(self):
self.assertEqual(t.timestamp(),
18000 + 3600 + 2*60 + 3 + 4*1e-6)

@unittest.skipUnless(sys.platform == "win32", "This only overflows on Windows")
def test_timestamp_overflow_windows(self):
t = self.theclass(9000, 1, 1, 1, 2, 3, 4)
self.assertRaises(OverflowError, t.timestamp)

@support.run_with_tz('MSK-03') # Something east of Greenwich
def test_microsecond_rounding(self):
for fts in [self.theclass.fromtimestamp,
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2023-04-20-18-51-57.gh-issue-103648.rXB8z5.rst
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@@ -0,0 +1 @@
Make :func:`datetime.datetime.timestamp()` raise ``OverflowError`` when overflow on Windows
11 changes: 10 additions & 1 deletion Python/pytime.c
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Expand Up @@ -1307,8 +1307,17 @@ _PyTime_localtime(time_t t, struct tm *tm)

error = localtime_s(tm, &t);
if (error != 0) {
// There are only 3 cases where an error could occur:
// * tm is NULL
// * &t is NULL (impossible in this usage)
// * it overflows (t < 0 or t > _MAX__TIME64_T)
errno = error;
PyErr_SetFromErrno(PyExc_OSError);
if (tm == NULL) {
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How is it possible that tm becomes NULL after calling localtime_s()? Is it a macro which sets tm on error? _PyTime_localtime() must not be called with tm=NULL.

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This is the case listed by localtime_s. I did not find any existing usage that could possibly call _PyTime_localtime with tm = NULL, but I did not find any documentation for it either. Of course it does not quite make sense to call it with tm = NULL, but if someone ran into the issue in the future(for example, did a _PyTime_localtime(t, tm_ptr) and forgot to check the pointer), they would get an OverflowError instead of an OSError, which would be confusing.

So two things we can do:

  1. Leave it as it is as a sanity check - the code path is kind of dead as of now, but could benefit in the future.
  2. Document that tm can't be NULL in the comments and/or do an assertion in the function.

I'm fine with either solution.

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Please add an assertion to ensure that the function is never called with tm=NULL. A runtime check is not needed. Right, private functions are not documented.

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Done, thanks for the review!

PyErr_SetFromErrno(PyExc_OSError);
} else {
PyErr_SetString(PyExc_OverflowError,
"localtime argument out of range");
}
return -1;
}
return 0;
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