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gh-116946: fully implement GC protocol for lzma objects #138288

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Merged
merged 4 commits into from
Sep 1, 2025
Merged

gh-116946: fully implement GC protocol for lzma objects #138288

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5d6ee9c
fully implement GC protocol for `lzma` objects
picnixz Aug 31, 2025
d32a93a
use `PyObject_GC_Del` for clarity
picnixz Aug 31, 2025
c13af3c
reduce diff for 3.14 and later
picnixz Aug 31, 2025
a76e4bc
smash diff
picnixz Aug 31, 2025
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37 changes: 22 additions & 15 deletions Modules/_lzmamodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -809,11 +809,14 @@ Compressor_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
return NULL;
}

assert(type != NULL && type->tp_alloc != NULL);
self = (Compressor *)type->tp_alloc(type, 0);
assert(type != NULL);
self = PyObject_GC_New(Compressor, type);
if (self == NULL) {
return NULL;
}
/* Initialize the remaining fields (untouched by PyObject_GC_New()). */
const size_t offset = sizeof(struct { PyObject_HEAD });
memset((char *)self + offset, 0, sizeof(*self) - offset);

self->alloc.opaque = NULL;
self->alloc.alloc = PyLzma_Malloc;
Expand All @@ -827,7 +830,6 @@ Compressor_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
return NULL;
}

self->flushed = 0;
switch (format) {
case FORMAT_XZ:
if (check == -1) {
Expand Down Expand Up @@ -856,6 +858,7 @@ Compressor_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
goto error;
}

PyObject_GC_Track(self);
return (PyObject *)self;

error:
Expand All @@ -866,13 +869,14 @@ Compressor_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
static void
Compressor_dealloc(PyObject *op)
{
PyTypeObject *tp = Py_TYPE(op);
PyObject_GC_UnTrack(op);
Compressor *self = Compressor_CAST(op);
lzma_end(&self->lzs);
if (self->lock != NULL) {
PyThread_free_lock(self->lock);
}
PyTypeObject *tp = Py_TYPE(self);
tp->tp_free(self);
PyObject_GC_Del(self);
Py_DECREF(tp);
}

Expand Down Expand Up @@ -933,7 +937,7 @@ static PyType_Spec lzma_compressor_type_spec = {
// lzma_compressor_type_spec does not have Py_TPFLAGS_BASETYPE flag
// which prevents to create a subclass.
// So calling PyType_GetModuleState() in this file is always safe.
.flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE),
.flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE | Py_TPFLAGS_HAVE_GC),
.slots = lzma_compressor_type_slots,
};

Expand Down Expand Up @@ -1241,16 +1245,19 @@ _lzma_LZMADecompressor_impl(PyTypeObject *type, int format,
return NULL;
}

assert(type != NULL && type->tp_alloc != NULL);
self = (Decompressor *)type->tp_alloc(type, 0);
assert(type != NULL);
self = PyObject_GC_New(Decompressor, type);
if (self == NULL) {
return NULL;
}
/* Initialize the remaining fields (untouched by PyObject_GC_New()). */
const size_t offset = sizeof(struct { PyObject_HEAD });
memset((char *)self + offset, 0, sizeof(*self) - offset);

self->alloc.opaque = NULL;
self->alloc.alloc = PyLzma_Malloc;
self->alloc.free = PyLzma_Free;
self->lzs.allocator = &self->alloc;
self->lzs.next_in = NULL;

self->lock = PyThread_allocate_lock();
if (self->lock == NULL) {
Expand All @@ -1261,9 +1268,7 @@ _lzma_LZMADecompressor_impl(PyTypeObject *type, int format,

self->check = LZMA_CHECK_UNKNOWN;
self->needs_input = 1;
self->input_buffer = NULL;
self->input_buffer_size = 0;
Py_XSETREF(self->unused_data, PyBytes_FromStringAndSize(NULL, 0));
self->unused_data = PyBytes_FromStringAndSize(NULL, 0);
if (self->unused_data == NULL) {
goto error;
}
Expand Down Expand Up @@ -1304,6 +1309,7 @@ _lzma_LZMADecompressor_impl(PyTypeObject *type, int format,
goto error;
}

PyObject_GC_Track(self);
return (PyObject *)self;

error:
Expand All @@ -1314,6 +1320,8 @@ _lzma_LZMADecompressor_impl(PyTypeObject *type, int format,
static void
Decompressor_dealloc(PyObject *op)
{
PyTypeObject *tp = Py_TYPE(op);
PyObject_GC_UnTrack(op);
Decompressor *self = Decompressor_CAST(op);
if(self->input_buffer != NULL)
PyMem_Free(self->input_buffer);
Expand All @@ -1323,8 +1331,7 @@ Decompressor_dealloc(PyObject *op)
if (self->lock != NULL) {
PyThread_free_lock(self->lock);
}
PyTypeObject *tp = Py_TYPE(self);
tp->tp_free(self);
PyObject_GC_Del(self);
Py_DECREF(tp);
}

Expand Down Expand Up @@ -1381,7 +1388,7 @@ static PyType_Spec lzma_decompressor_type_spec = {
// lzma_decompressor_type_spec does not have Py_TPFLAGS_BASETYPE flag
// which prevents to create a subclass.
// So calling PyType_GetModuleState() in this file is always safe.
.flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE),
.flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE | Py_TPFLAGS_HAVE_GC),
.slots = lzma_decompressor_type_slots,
};

Expand Down
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