zooba · May 10, 2024 · Apr 24, 2024 · Apr 24, 2024 · Apr 24, 2024 · Apr 25, 2024
@@ -568,6 +568,9 @@ mmap
 * :class:`mmap.mmap` now has a *trackfd* parameter on Unix; if it is ``False``,
   the file descriptor specified by *fileno* will not be duplicated.
   (Contributed by Zackery Spytz and Petr Viktorin in :gh:`78502`.)
+* :class:`mmap.mmap` is now protected from crashing on Windows when the mapped memory
+  is inaccessible due to file system errors or access violations.
+  (Contributed by Jannis Weigend in :gh:`118209`.)
 
 opcode
 ------

diff --git a/Lib/test/test_mmap.py b/Lib/test/test_mmap.py
@@ -3,6 +3,7 @@
 )
 from test.support.import_helper import import_module
 from test.support.os_helper import TESTFN, unlink
+from test.support.script_helper import assert_python_ok
 import unittest
 import errno
 import os
@@ -12,6 +13,7 @@
 import socket
 import string
 import sys
+import textwrap
 import weakref
 
 # Skip test if we can't import mmap.
@@ -1058,6 +1060,81 @@ def __exit__(self, exc_type, exc_value, traceback):
                 with self.assertRaisesRegex(ValueError, "mmap closed or invalid"):
                     m.write_byte(X())
 
+    @unittest.skipUnless(os.name == 'nt', 'requires Windows')
+    @unittest.skipUnless(hasattr(mmap.mmap, '_protect'), 'test needs debug build')
+    def test_access_violations(self):
+        from test.support.os_helper import TESTFN
+
+        code = textwrap.dedent("""
+            import faulthandler
+            import mmap
+            import os
+            import sys
+            from contextlib import suppress
+
+            # Prevent logging access violations to stderr.
+            faulthandler.disable()
+
+            PAGESIZE = mmap.PAGESIZE
+            PAGE_NOACCESS = 0x01
+
+            with open(sys.argv[1], 'bw+') as f:
+                f.write(b'A'* PAGESIZE)
+                f.flush()
+
+                m = mmap.mmap(f.fileno(), PAGESIZE)
+                m._protect(PAGE_NOACCESS, 0, PAGESIZE)
+                with suppress(OSError):
+                    m.read(PAGESIZE)
+                    assert False, 'mmap.read() did not raise'
+                with suppress(OSError):
+                    m.read_byte()
+                    assert False, 'mmap.read_byte() did not raise'
+                with suppress(OSError):
+                    m.readline()
+                    assert False, 'mmap.readline() did not raise'
+                with suppress(OSError):
+                    m.write(b'A'* PAGESIZE)
+                    assert False, 'mmap.write() did not raise'
+                with suppress(OSError):
+                    m.write_byte(0)
+                    assert False, 'mmap.write_byte() did not raise'
+                with suppress(OSError):
+                    m[0]  # test mmap_subscript
+                    assert False, 'mmap.__getitem__() did not raise'
+                with suppress(OSError):
+                    m[0:10]  # test mmap_subscript
+                    assert False, 'mmap.__getitem__() did not raise'
+                with suppress(OSError):
+                    m[0:10:2]  # test mmap_subscript
+                    assert False, 'mmap.__getitem__() did not raise'
+                with suppress(OSError):
+                    m[0] = 1
+                    assert False, 'mmap.__setitem__() did not raise'
+                with suppress(OSError):
+                    m[0:10] = b'A'* 10
+                    assert False, 'mmap.__setitem__() did not raise'
+                with suppress(OSError):
+                    m[0:10:2] = b'A'* 5
+                    assert False, 'mmap.__setitem__() did not raise'
+                with suppress(OSError):
+                    m.move(0, 10, 1)
+                    assert False, 'mmap.move() did not raise'
+                with suppress(OSError):
+                    list(m)  # test mmap_item
+                    assert False, 'mmap.__getitem__() did not raise'
+                with suppress(OSError):
+                    m.find(b'A')
+                    assert False, 'mmap.find() did not raise'
+                with suppress(OSError):
+                    m.rfind(b'A')
+                    assert False, 'mmap.rfind() did not raise'
+        """)
+        rt, stdout, stderr = assert_python_ok("-c", code, TESTFN)
+        self.assertEqual(stdout.strip(), b'')
+        self.assertEqual(stderr.strip(), b'')
+
+
 class LargeMmapTests(unittest.TestCase):
 
     def setUp(self):

diff --git a/Misc/NEWS.d/next/Windows/2024-04-24-05-16-32.gh-issue-118209.Ryyzlz.rst b/Misc/NEWS.d/next/Windows/2024-04-24-05-16-32.gh-issue-118209.Ryyzlz.rst
@@ -0,0 +1,2 @@
+Avoid crashing in :mod:`mmap` on Windows when the mapped memory is inaccessible
+due to file system errors or access violations.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Avoid crashing in :mod:`mmap` on Windows when the mapped memory is inaccessible
		due to file system errors or access violations.