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gh-142451: correctly copy HMAC attributes in HMAC.copy() #142510

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Merged
picnixz merged 1 commit into from
Dec 14, 2025
Merged

gh-142451: correctly copy HMAC attributes in HMAC.copy() #142510

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1 change: 1 addition & 0 deletions Lib/hmac.py
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Original file line number Diff line number Diff line change
Expand Up @@ -171,6 +171,7 @@ def copy(self):
# Call __new__ directly to avoid the expensive __init__.
other = self.__class__.__new__(self.__class__)
other.digest_size = self.digest_size
other.block_size = self.block_size
if self._hmac:
other._hmac = self._hmac.copy()
other._inner = other._outer = None
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9 changes: 9 additions & 0 deletions Lib/test/test_hmac.py
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Expand Up @@ -1076,6 +1076,15 @@ def test_properties(self):
self.assertEqual(h.digest_size, self.digest_size)
self.assertEqual(h.block_size, self.block_size)

def test_copy(self):
# Test a generic copy() and the attributes it exposes.
# See https://github.com/python/cpython/issues/142451.
h1 = self.hmac_new(b"my secret key", digestmod=self.digestname)
h2 = h1.copy()
self.assertEqual(h1.name, h2.name)
self.assertEqual(h1.digest_size, h2.digest_size)
self.assertEqual(h1.block_size, h2.block_size)

def test_repr(self):
# HMAC object representation may differ across implementations
raise NotImplementedError
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2025-12-10-11-02-53.gh-issue-142451.eCLvhG.rst
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@@ -0,0 +1,2 @@
:mod:`hmac`: correctly copy :class:`~hmac.HMAC` attributes for objects
copied through :meth:`HMAC.copy() <hmac.HMAC.copy>`. Patch by Bénédikt Tran.
14 changes: 11 additions & 3 deletions Modules/_hashopenssl.c
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Expand Up @@ -606,9 +606,14 @@ get_asn1_utf8name_by_nid(int nid)
{
const char *name = OBJ_nid2ln(nid);
if (name == NULL) {
// In OpenSSL 3.0 and later, OBJ_nid*() are thread-safe and may raise.
assert(ERR_peek_last_error() != 0);
if (ERR_GET_REASON(ERR_peek_last_error()) != OBJ_R_UNKNOWN_NID) {
/* In OpenSSL 3.0 and later, OBJ_nid*() are thread-safe and may raise.
* However, not all versions of OpenSSL set a last error, so we simply
* ignore the last error if none exists.
*
* See https://github.com/python/cpython/issues/142451.
*/
unsigned long errcode = ERR_peek_last_error();
if (errcode && ERR_GET_REASON(errcode) != OBJ_R_UNKNOWN_NID) {
goto error;
}
// fallback to short name and unconditionally propagate errors
Expand Down Expand Up @@ -2255,6 +2260,9 @@ _hashlib_HMAC_copy_impl(HMACobject *self)
return NULL;
}
retval->ctx = ctx;
#ifdef Py_HAS_OPENSSL3_SUPPORT
retval->evp_md_nid = self->evp_md_nid;
#endif
HASHLIB_INIT_MUTEX(retval);
return (PyObject *)retval;
}
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