gh-118209: Add structured exception handling to mmap module

Doc/whatsnew/3.13.rst

@@ -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
 ------

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):

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.