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[3.13] gh-118209: Add Windows structured exception handling to mmap module (GH-118213) #118887

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Merged
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May 10, 2024
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[3.13] gh-118209: Add Windows structured exception handling to mmap module (GH-118213) #118887

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3 changes: 3 additions & 0 deletions Doc/whatsnew/3.13.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -796,6 +796,9 @@ 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
------
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77 changes: 77 additions & 0 deletions Lib/test/test_mmap.py
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -12,6 +13,7 @@
import socket
import string
import sys
import textwrap
import weakref

# Skip test if we can't import mmap.
Expand Down Expand Up @@ -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):
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Windows/2024-04-24-05-16-32.gh-issue-118209.Ryyzlz.rst
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@@ -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.
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