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gh-156865: don't raise exceptions for overflows in the ctypes module #156919

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gh-156865: don't raise exceptions for overflows in the ctypes module #156919

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ca96502
gh-156865: don't raise exceptions for overflows in the ctypes module
skirpichev Sep 4, 2026
bb3fd9e
skip that for poor childrens
skirpichev Sep 4, 2026
e7afd4e
Merge branch 'main' into fix-ctypes-Zf_set_sw
skirpichev Sep 4, 2026
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17 changes: 17 additions & 0 deletions Lib/test/test_ctypes/test_numbers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -231,6 +231,8 @@ def test_init(self):
# probably be changed:
self.assertRaises(TypeError, c_int, c_long(42))

@unittest.skipUnless(hasattr(ctypes, "c_double_complex"),
"requires C11 complex type")
def test_float_overflow(self):
big_int = int(sys.float_info.max) * 2
for t in float_types + [c_longdouble]:
Expand All @@ -240,6 +242,21 @@ def test_float_overflow(self):
if (hasattr(t, "__ctype_le__")):
self.assertRaises(OverflowError, t.__ctype_le__, big_int)

# gh-156865: be silent in overflows of C types
self.assertEqual(ctypes.c_float(3e300).value, float('inf'))
self.assertEqual(ctypes.c_float.__ctype_le__(3e300).value, float('inf'))
self.assertEqual(ctypes.c_float.__ctype_be__(3e300).value, float('inf'))
self.assertEqual(ctypes.c_float_complex(3e300).value, complex('inf'))
self.assertEqual(ctypes.c_float_complex.__ctype_le__(3e300).value,
complex('inf'))
self.assertEqual(ctypes.c_float_complex.__ctype_be__(3e300).value,
complex('inf'))
self.assertEqual(ctypes.c_float_complex(3e300j).value, complex('infj'))
self.assertEqual(ctypes.c_float_complex.__ctype_le__(3e300j).value,
complex('infj'))
self.assertEqual(ctypes.c_float_complex.__ctype_be__(3e300j).value,
complex('infj'))


if __name__ == '__main__':
unittest.main()
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2026-09-04-11-45-08.gh-issue-156865.mrdfKJ.rst
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@@ -0,0 +1,2 @@
Don't raise exceptions on overflows in floating-point types of the
:mod:`ctypes`. Patch by Sergey B Kirpichev.
8 changes: 4 additions & 4 deletions Modules/_ctypes/cfield.c
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Expand Up @@ -865,14 +865,14 @@ Zf_set_sw(void *ptr, PyObject *value, Py_ssize_t size)
return NULL;
}
#ifdef WORDS_BIGENDIAN
if (PyFloat_Pack4(c.real, ptr, 1)
|| PyFloat_Pack4(c.imag, ptr + sizeof(float), 1))
if (PyFloat_Pack4((float)c.real, ptr, 1)
|| PyFloat_Pack4((float)c.imag, ptr + sizeof(float), 1))
{
return NULL;
}
#else
if (PyFloat_Pack4(c.real, ptr, 0)
|| PyFloat_Pack4(c.imag, ptr + sizeof(float), 0))
if (PyFloat_Pack4((float)c.real, ptr, 0)
|| PyFloat_Pack4((float)c.imag, ptr + sizeof(float), 0))
{
return NULL;
}
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