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gh-78502: Add a trackfd parameter to mmap.mmap() #25425

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Merged
encukou merged 16 commits into from
Jan 16, 2024
Merged

gh-78502: Add a trackfd parameter to mmap.mmap() #25425

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d42762c
bpo-34321: Add a trackfd parameter to mmap.mmap()
ZackerySpytz Apr 15, 2021
8d141ad
Merge branch 'main' into bpo-34321-mmap-trackfd-parameter
erlend-aasland Jan 5, 2024
12705a6
Merge in the main branch
encukou Jan 9, 2024
42302bc
Make the trackfd argument keyword-only
encukou Jan 9, 2024
9443f1f
Add smoke tests for a mmap with trackfd=False
encukou Jan 9, 2024
eb8d798
Update documentation
encukou Jan 9, 2024
8f05c7b
Make resize() fail with trackfd=False
encukou Jan 9, 2024
b207558
Test with original fd closed after creating mmap
encukou Jan 9, 2024
7607593
Document trackfd as keyword-only
encukou Jan 9, 2024
2d90229
Update docstring
encukou Jan 9, 2024
0a717f8
Test with fd=-1, and that this fails on Windows
encukou Jan 9, 2024
7364a27
Test the errno
encukou Jan 9, 2024
eca802c
Move the What's New entry to 3.13
encukou Jan 10, 2024
51bb4e5
Raise ValueEror on resize
encukou Jan 10, 2024
d274952
Fix Sphinx warning
encukou Jan 10, 2024
e33a7fd
Note why you might want to use this
encukou Jan 15, 2024
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Test with fd=-1, and that this fails on Windows
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@encukou
encukou committed Jan 9, 2024
commit 0a717f8d6aad1a44dc9dd85c301e8a91c1e6418e
21 changes: 21 additions & 0 deletions Lib/test/test_mmap.py
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Original file line number Diff line number Diff line change
Expand Up @@ -300,6 +300,27 @@ def test_trackfd_parameter(self):
self.assertEqual(m.closed, True)
self.assertEqual(os.stat(TESTFN).st_size, size)

@unittest.skipIf(os.name == 'nt', 'trackfd not present on Windows')
def test_trackfd_neg1(self):
size = 64
with mmap.mmap(-1, size, trackfd=False) as m:
with self.assertRaises(OSError):
m.size()
with self.assertRaises(TypeError):
m.resize(size // 2)
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@serhiy-storchaka serhiy-storchaka Jan 9, 2024

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Does it work the same for mmap(-1, size, trackfd=True)? I have not found tests for this.

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@encukou encukou Jan 10, 2024

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trackfd=True is the default. It's tested in test_resize_past_pos.

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@serhiy-storchaka serhiy-storchaka Jan 10, 2024

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It has different behavior. Should trackfd=False have any effect for fd=-1? Should combination fd=-1 and trackfd=False be allowed?

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@encukou encukou Jan 10, 2024

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Conceptually, trackfd=False should be the only possible behaviour for fd=-1 -- the fd is not tracked.
However, I don't think it's worth it to include a third value for “trackfd=default”. As it is, the default (True) works as before. Setting False has the documented effect -- disabling resize. This isn't very useful, but I don't think it's worth handling specially.

self.assertEqual(len(m), size)
m[0] = ord('a')
assert m[0] == ord('a')

@unittest.skipIf(os.name != 'nt', 'trackfd only fails on Windows')
def test_no_trackfd_parameter_on_windows(self):
# 'trackffd' is an invalid keyword argument for this function
size = 64
with self.assertRaises(TypeError):
mmap.mmap(-1, size, trackfd=True)
with self.assertRaises(TypeError):
mmap.mmap(-1, size, trackfd=False)

def test_bad_file_desc(self):
# Try opening a bad file descriptor...
self.assertRaises(OSError, mmap.mmap, -2, 4096)
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