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gh-83714: Fix stat_nanosecond_timestamp() for 32-bit time_t#141069

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Merged
vstinner merged 1 commit into from
Nov 5, 2025
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gh-83714: Fix stat_nanosecond_timestamp() for 32-bit time_t #141069

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6 changes: 4 additions & 2 deletions Modules/posixmodule.c
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Original file line numberDiff line numberDiff line change
Expand Up@@ -2634,13 +2634,14 @@ _posix_free(void *module)
static PyObject *
stat_nanosecond_timestamp(_posixstate *state, time_t sec, unsigned long nsec)
{
#if SIZEOF_LONG >= 8
#if SIZEOF_TIME_T == 4
return PyLong_FromLongLong(sec * SEC_TO_NS + nsec);

@serhiy-storchakaserhiy-storchakaNov 5, 2025

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What is the type of SEC_TO_NS? Should not it or sec be cast to long long?

We will get a warning also in the very unlikely case of more than 64-bit long long. Maybe use condition SIZEOF_TIME_T + 4 <= SIZEOF_LONG_LONG?

@vstinnervstinnerNov 5, 2025

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What is the type of SEC_TO_NS?

It's a long long: it uses the LL suffix.

@vstinnervstinnerNov 5, 2025

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We will get a warning also in the very unlikely case of more than 64-bit long long.

I don't see which kind of warning would be emitted if long long is larger than 64-bit?

@serhiy-storchakaserhiy-storchakaNov 5, 2025

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The same warning. If long long is 128-bit and time_t is 64-bit, then the condition (LLONG_MIN/SEC_TO_NS) <= sec && sec <= (LLONG_MAX/SEC_TO_NS - 1) will be tested, and it will be always true.

I do not know if Python is currently used on any platform with larger than 64-bit long long. This is hypothetical.

@serhiy-storchakaserhiy-storchakaNov 5, 2025

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Anyway, this would be just a warning. Not wrong code or missed optimization.

@vstinnervstinnerNov 5, 2025

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If long long is 128-bit and time_t is 64-bit

Oh ok. Well, I expect many warnings if long long is larger than 64-bit, not just on these lines. We can revisit the code once such platform will exist :-)

#else
/* 1677-09-21 00:12:44 to 2262-04-11 23:47:15 UTC inclusive */
if ((LLONG_MIN/SEC_TO_NS) <= sec && sec <= (LLONG_MAX/SEC_TO_NS - 1)) {
return PyLong_FromLongLong(sec * SEC_TO_NS + nsec);
}
else
#endif
{
PyObject *ns_total = NULL;
PyObject *s_in_ns = NULL;
Expand All@@ -2663,6 +2664,7 @@ stat_nanosecond_timestamp(_posixstate *state, time_t sec, unsigned long nsec)
Py_XDECREF(s_in_ns);
return ns_total;
}
#endif
}

static int
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