From 77d9d68812411191f3ca9437382734381dbde0df Mon Sep 17 00:00:00 2001
From: Crowthebird <78076854+thatbirdguythatuknownot@users.noreply.github.com>
Date: Mon, 14 Mar 2022 09:23:59 +0800
Subject: [PATCH] bpo-39829: Fix `__len__()` is called twice in list()
constructor (GH-31816) (cherry picked from commit
2153daf0a02a598ed5df93f2f224c1ab2a2cca0d)
Co-authored-by: Crowthebird <78076854+thatbirdguythatuknownot@users.noreply.github.com>
---
Misc/ACKS | 1 +
.../2022-03-11-09-39-01.bpo-39829.mlW3Su.rst | 1 +
Objects/listobject.c | 29 ++++++++-----------
3 files changed, 14 insertions(+), 17 deletions(-)
create mode 100644 Misc/NEWS.d/next/Core and Builtins/2022-03-11-09-39-01.bpo-39829.mlW3Su.rst
diff --git a/Misc/ACKS b/Misc/ACKS
index 889bf8aeaea1ac..b83f99956de0b1 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1332,6 +1332,7 @@ William Park
Claude Paroz
Heikki Partanen
Harri Pasanen
+Jeremiah Gabriel Pascual
Gaël Pasgrimaud
Feanil Patel
Ashish Nitin Patil
diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-03-11-09-39-01.bpo-39829.mlW3Su.rst b/Misc/NEWS.d/next/Core and Builtins/2022-03-11-09-39-01.bpo-39829.mlW3Su.rst
new file mode 100644
index 00000000000000..1f3d945188a32a
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-03-11-09-39-01.bpo-39829.mlW3Su.rst
@@ -0,0 +1 @@
+Removed the ``__len__()`` call when initializing a list and moved initializing to ``list_extend``. Patch by Jeremiah Pascual.
diff --git a/Objects/listobject.c b/Objects/listobject.c
index d3bc5766df7a0b..7f37b7386051d0 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -863,7 +863,6 @@ list_extend(PyListObject *self, PyObject *iterable)
PyObject *it; /* iter(v) */
Py_ssize_t m; /* size of self */
Py_ssize_t n; /* guess for size of iterable */
- Py_ssize_t mn; /* m + n */
Py_ssize_t i;
PyObject *(*iternext)(PyObject *);
@@ -887,7 +886,13 @@ list_extend(PyListObject *self, PyObject *iterable)
/* It should not be possible to allocate a list large enough to cause
an overflow on any relevant platform */
assert(m < PY_SSIZE_T_MAX - n);
- if (list_resize(self, m + n) < 0) {
+ if (self->ob_item == NULL) {
+ if (list_preallocate_exact(self, n) < 0) {
+ return NULL;
+ }
+ Py_SET_SIZE(self, n);
+ }
+ else if (list_resize(self, m + n) < 0) {
Py_DECREF(iterable);
return NULL;
}
@@ -926,10 +931,13 @@ list_extend(PyListObject *self, PyObject *iterable)
* eventually run out of memory during the loop.
*/
}
+ else if (self->ob_item == NULL) {
+ if (n && list_preallocate_exact(self, n) < 0)
+ goto error;
+ }
else {
- mn = m + n;
/* Make room. */
- if (list_resize(self, mn) < 0)
+ if (list_resize(self, m + n) < 0)
goto error;
/* Make the list sane again. */
Py_SET_SIZE(self, m);
@@ -2717,19 +2725,6 @@ list___init___impl(PyListObject *self, PyObject *iterable)
(void)_list_clear(self);
}
if (iterable != NULL) {
- if (_PyObject_HasLen(iterable)) {
- Py_ssize_t iter_len = PyObject_Size(iterable);
- if (iter_len == -1) {
- if (!PyErr_ExceptionMatches(PyExc_TypeError)) {
- return -1;
- }
- PyErr_Clear();
- }
- if (iter_len > 0 && self->ob_item == NULL
- && list_preallocate_exact(self, iter_len)) {
- return -1;
- }
- }
PyObject *rv = list_extend(self, iterable);
if (rv == NULL)
return -1;
pFad - Phonifier reborn
Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.
Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.
Alternative Proxies:
Alternative Proxy
pFad Proxy
pFad v3 Proxy
pFad v4 Proxy