https://github.com/python/cpython/commit/bd1ada6df35f29069fc478ce3b0fee3372df075a
commit: bd1ada6df35f29069fc478ce3b0fee3372df075a
branch: main
author: AN Long <[email protected]>
committer: encukou <[email protected]>
date: 2025-09-30T11:08:50+02:00
summary:
gh-138092: Allow calling mmap.flush with offset only (#138093)
files:
A Misc/NEWS.d/next/Library/2025-08-24-02-04-32.gh-issue-138092.V4-wTO.rst
M Doc/library/mmap.rst
M Lib/test/test_mmap.py
M Modules/mmapmodule.c
diff --git a/Doc/library/mmap.rst b/Doc/library/mmap.rst
index bd3f7229bdaf70..b6ffb5cebc020e 100644
--- a/Doc/library/mmap.rst
+++ b/Doc/library/mmap.rst
@@ -212,8 +212,7 @@ To map anonymous memory, -1 should be passed as the fileno
along with the length
Writable :term:`bytes-like object` is now accepted.
- .. method:: flush()
- flush(offset, size, /)
+ .. method:: flush([offset[, size]])
Flushes changes made to the in-memory copy of a file back to disk.
Without
use of this call there is no guarantee that changes are written back
before
@@ -230,6 +229,12 @@ To map anonymous memory, -1 should be passed as the fileno
along with the length
on error under Windows. A zero value was returned on success; an
exception was raised on error under Unix.
+ .. versionchanged:: next
+ Allow specifying *offset* without *size*. Previously, both *offset*
+ and *size* parameters were required together. Now *offset* can be
+ specified alone, and the flush operation will extend from *offset*
+ to the end of the mmap.
+
.. method:: madvise(option[, start[, length]])
diff --git a/Lib/test/test_mmap.py b/Lib/test/test_mmap.py
index 75ea1a671b67de..0571eed23f72dc 100644
--- a/Lib/test/test_mmap.py
+++ b/Lib/test/test_mmap.py
@@ -1145,6 +1145,18 @@ def test_access_violations(self):
self.assertEqual(stdout.strip(), b'')
self.assertEqual(stderr.strip(), b'')
+ def test_flush_parameters(self):
+ with open(TESTFN, 'wb+') as f:
+ f.write(b'x' * PAGESIZE * 3)
+ f.flush()
+
+ m = mmap.mmap(f.fileno(), PAGESIZE * 3)
+ self.addCleanup(m.close)
+
+ m.flush()
+ m.flush(PAGESIZE)
+ m.flush(PAGESIZE, PAGESIZE)
+
class LargeMmapTests(unittest.TestCase):
diff --git
a/Misc/NEWS.d/next/Library/2025-08-24-02-04-32.gh-issue-138092.V4-wTO.rst
b/Misc/NEWS.d/next/Library/2025-08-24-02-04-32.gh-issue-138092.V4-wTO.rst
new file mode 100644
index 00000000000000..21c28c49628cba
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-08-24-02-04-32.gh-issue-138092.V4-wTO.rst
@@ -0,0 +1,2 @@
+Fixed a bug in :meth:`mmap.mmap.flush` where calling with only an offset
+parameter would fail.
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index 8caadde8ae211b..41d117162882d7 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -933,11 +933,15 @@ static PyObject *
mmap_flush_method(PyObject *op, PyObject *args)
{
Py_ssize_t offset = 0;
+ Py_ssize_t size = -1;
mmap_object *self = mmap_object_CAST(op);
- Py_ssize_t size = self->size;
CHECK_VALID(NULL);
- if (!PyArg_ParseTuple(args, "|nn:flush", &offset, &size))
+ if (!PyArg_ParseTuple(args, "|nn:flush", &offset, &size)) {
return NULL;
+ }
+ if (size == -1) {
+ size = self->size - offset;
+ }
if (size < 0 || offset < 0 || self->size - offset < size) {
PyErr_SetString(PyExc_ValueError, "flush values out of range");
return NULL;
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