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gh-113993: For string interning, do not rely on (or assert) _Py_IsImmortal (GH-121358)

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Older stable ABI extensions are allowed to make immortal objects mortal.
Instead, use `_PyUnicode_STATE` (`interned` and `statically_allocated`).
This commit is contained in:
Petr Viktorin 2024-07-16 15:17:29 +02:00 • committed by GitHub
parent a0b205bba5
commit 956270d08d
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2 changed files with 10 additions and 7 deletions
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2
Misc/NEWS.d/next/C API/2024-07-04-13-23-27.gh-issue-113601.K3RLqp.rst Normal file
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@ -0,0 +1,2 @@
Removed debug build assertions related to interning strings, which were
falsely triggered by stable ABI extensions.

15
Objects/unicodeobject.c
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@ -252,7 +252,8 @@ _PyUnicode_InternedSize_Immortal(void)
// value, to help detect bugs in optimizations. // value, to help detect bugs in optimizations.
while (PyDict_Next(dict, &pos, &key, &value)) { while (PyDict_Next(dict, &pos, &key, &value)) {
if (_Py_IsImmortal(key)) { assert(PyUnicode_CHECK_INTERNED(key) != SSTATE_INTERNED_IMMORTAL_STATIC);
if (PyUnicode_CHECK_INTERNED(key) == SSTATE_INTERNED_IMMORTAL) {
count++; count++;
} }
} }
@ -688,10 +689,14 @@ _PyUnicode_CheckConsistency(PyObject *op, int check_content)
/* Check interning state */ /* Check interning state */
#ifdef Py_DEBUG #ifdef Py_DEBUG
// Note that we do not check `_Py_IsImmortal(op)`, since stable ABI
// extensions can make immortal strings mortal (but with a high enough
// refcount).
// The other way is extremely unlikely (worth a potential failed assertion
// in a debug build), so we do check `!_Py_IsImmortal(op)`.
switch (PyUnicode_CHECK_INTERNED(op)) { switch (PyUnicode_CHECK_INTERNED(op)) {
case SSTATE_NOT_INTERNED: case SSTATE_NOT_INTERNED:
if (ascii->state.statically_allocated) { if (ascii->state.statically_allocated) {
CHECK(_Py_IsImmortal(op));
// This state is for two exceptions: // This state is for two exceptions:
// - strings are currently checked before they're interned // - strings are currently checked before they're interned
// - the 256 one-latin1-character strings // - the 256 one-latin1-character strings
@ -707,11 +712,9 @@ _PyUnicode_CheckConsistency(PyObject *op, int check_content)
break; break;
case SSTATE_INTERNED_IMMORTAL: case SSTATE_INTERNED_IMMORTAL:
CHECK(!ascii->state.statically_allocated); CHECK(!ascii->state.statically_allocated);
CHECK(_Py_IsImmortal(op));
break; break;
case SSTATE_INTERNED_IMMORTAL_STATIC: case SSTATE_INTERNED_IMMORTAL_STATIC:
CHECK(ascii->state.statically_allocated); CHECK(ascii->state.statically_allocated);
CHECK(_Py_IsImmortal(op));
break; break;
default: default:
Py_UNREACHABLE(); Py_UNREACHABLE();
@ -1867,7 +1870,6 @@ static PyObject*
get_latin1_char(Py_UCS1 ch) get_latin1_char(Py_UCS1 ch)
{ {
PyObject *o = LATIN1(ch); PyObject *o = LATIN1(ch);
assert(_Py_IsImmortal(o));
return o; return o;
} }
@ -15352,7 +15354,6 @@ intern_static(PyInterpreterState *interp, PyObject *s /* stolen */)
assert(s != NULL); assert(s != NULL);
assert(_PyUnicode_CHECK(s)); assert(_PyUnicode_CHECK(s));
assert(_PyUnicode_STATE(s).statically_allocated); assert(_PyUnicode_STATE(s).statically_allocated);
assert(_Py_IsImmortal(s));
switch (PyUnicode_CHECK_INTERNED(s)) { switch (PyUnicode_CHECK_INTERNED(s)) {
case SSTATE_NOT_INTERNED: case SSTATE_NOT_INTERNED:
@ -15493,7 +15494,7 @@ intern_common(PyInterpreterState *interp, PyObject *s /* stolen */,
{ {
PyObject *r = (PyObject *)_Py_hashtable_get(INTERNED_STRINGS, s); PyObject *r = (PyObject *)_Py_hashtable_get(INTERNED_STRINGS, s);
if (r != NULL) { if (r != NULL) {
assert(_Py_IsImmortal(r)); assert(_PyUnicode_STATE(r).statically_allocated);
assert(r != s); // r must be statically_allocated; s is not assert(r != s); // r must be statically_allocated; s is not
Py_DECREF(s); Py_DECREF(s);
return Py_NewRef(r); return Py_NewRef(r);