https://github.com/python/cpython/commit/b93b7e566e5a4efe7f077af2083140e50bd2b08f
commit: b93b7e566e5a4efe7f077af2083140e50bd2b08f
branch: main
author: Serhiy Storchaka <[email protected]>
committer: serhiy-storchaka <[email protected]>
date: 2025-02-18T09:46:48+02:00
summary:
gh-130230: Fix crash in pow() with only Decimal third argument (GH-130237)
files:
A Misc/NEWS.d/next/Library/2025-02-17-21-16-51.gh-issue-130230.9ta9P9.rst
M Lib/test/test_decimal.py
M Modules/_decimal/_decimal.c
diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index 02d3fa985e75b9..0e15eb3693888d 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -4481,6 +4481,15 @@ def test_implicit_context(self):
self.assertIs(Decimal("NaN").fma(7, 1).is_nan(), True)
# three arg power
self.assertEqual(pow(Decimal(10), 2, 7), 2)
+ if self.decimal == C:
+ self.assertEqual(pow(10, Decimal(2), 7), 2)
+ self.assertEqual(pow(10, 2, Decimal(7)), 2)
+ else:
+ # XXX: Three-arg power doesn't use __rpow__.
+ self.assertRaises(TypeError, pow, 10, Decimal(2), 7)
+ # XXX: There is no special method to dispatch on the
+ # third arg of three-arg power.
+ self.assertRaises(TypeError, pow, 10, 2, Decimal(7))
# exp
self.assertEqual(Decimal("1.01").exp(), 3)
# is_normal
diff --git
a/Misc/NEWS.d/next/Library/2025-02-17-21-16-51.gh-issue-130230.9ta9P9.rst
b/Misc/NEWS.d/next/Library/2025-02-17-21-16-51.gh-issue-130230.9ta9P9.rst
new file mode 100644
index 00000000000000..20327fd5f25b43
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-02-17-21-16-51.gh-issue-130230.9ta9P9.rst
@@ -0,0 +1 @@
+Fix crash in :func:`pow` with only :class:`~decimal.Decimal` third argument.
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index 3dcb3e9870c8a4..8a24d8c12cab8a 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -147,6 +147,24 @@ find_state_left_or_right(PyObject *left, PyObject *right)
return (decimal_state *)state;
}
+static inline decimal_state *
+find_state_ternary(PyObject *left, PyObject *right, PyObject *modulus)
+{
+ PyTypeObject *base;
+ if (PyType_GetBaseByToken(Py_TYPE(left), &dec_spec, &base) != 1) {
+ assert(!PyErr_Occurred());
+ if (PyType_GetBaseByToken(Py_TYPE(right), &dec_spec, &base) != 1) {
+ assert(!PyErr_Occurred());
+ PyType_GetBaseByToken(Py_TYPE(modulus), &dec_spec, &base);
+ }
+ }
+ assert(base != NULL);
+ void *state = _PyType_GetModuleState(base);
+ assert(state != NULL);
+ Py_DECREF(base);
+ return (decimal_state *)state;
+}
+
#if !defined(MPD_VERSION_HEX) || MPD_VERSION_HEX < 0x02050000
#error "libmpdec version >= 2.5.0 required"
@@ -4407,7 +4425,7 @@ nm_mpd_qpow(PyObject *base, PyObject *exp, PyObject *mod)
PyObject *context;
uint32_t status = 0;
- decimal_state *state = find_state_left_or_right(base, exp);
+ decimal_state *state = find_state_ternary(base, exp, mod);
CURRENT_CONTEXT(state, context);
CONVERT_BINOP(&a, &b, base, exp, context);
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