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GeezerVison is showing github.com — `_io` and `_pyio` inconsistenly raise `ValueError`s on closed files · Issue #98999 · python/cpython

_io and _pyio inconsistenly raise ValueErrors on closed files #98999

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_io and _pyio inconsistenly raise ValueErrors on closed files#98999
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stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directorytopic-IOtype-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

Description

@sobolevn
sobolevn
opened on Nov 2, 2022
Issue body actions

While working on typeshed stubs, I've noticed that _pyio.BufferedReader.read1 does not raise ValueError after .close. While _io.BufferedReader.read1 does that.

So, I went to see both implementation and tests.

C source clearly checks for this here:

cpython/Modules/_io/bufferedio.c

Line 910 in 0689b99

CHECK_CLOSED(self, "read of closed file")

But, tests were not executed correctly. Tests were only covering C version: https://github.com/python/cpython/blame/0689b99bb8c4f6058af43a52effaa8a25609dbed/Lib/test/test_io.py#L1532-L1538

    def test_read_on_closed(self):
        # Issue #23796
        b = io.BufferedReader(io.BytesIO(b"12"))
        b.read(1)
        b.close()
        self.assertRaises(ValueError, b.peek)
        self.assertRaises(ValueError, b.read1, 1)

While universal test would look like this:

    def test_read_on_closed(self):
        # Issue #23796
        b = self.BufferedReader(self.BytesIO(b"12"))
        b.read(1)
        b.close()
        self.assertRaises(ValueError, b.peek)
        self.assertRaises(ValueError, b.read1, 1)

And now it is failing:

» ./python.exe -m test -v test_io -m test_read_on_closed
== CPython 3.12.0a1+ (heads/main:7ea10567af, Oct 29 2022, 13:15:59) [Clang 11.0.0 (clang-1100.0.33.16)]
== macOS-10.14.6-x86_64-i386-64bit little-endian
== cwd: /Users/sobolev/Desktop/cpython/build/test_python_78918æ
== CPU count: 4
== encodings: locale=UTF-8, FS=utf-8
0:00:00 load avg: 2.19 Run tests sequentially
0:00:00 load avg: 2.19 [1/1] test_io
test_read_on_closed (test.test_io.CBufferedReaderTest.test_read_on_closed) ... ok
test_read_on_closed (test.test_io.PyBufferedReaderTest.test_read_on_closed) ... FAIL
test_read_on_closed (test.test_io.CBufferedRandomTest.test_read_on_closed) ... ok
test_read_on_closed (test.test_io.PyBufferedRandomTest.test_read_on_closed) ... FAIL

======================================================================
FAIL: test_read_on_closed (test.test_io.PyBufferedReaderTest.test_read_on_closed)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/sobolev/Desktop/cpython/Lib/test/test_io.py", line 1537, in test_read_on_closed
    self.assertRaises(ValueError, b.peek)
AssertionError: ValueError not raised by peek

======================================================================
FAIL: test_read_on_closed (test.test_io.PyBufferedRandomTest.test_read_on_closed)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/sobolev/Desktop/cpython/Lib/test/test_io.py", line 1537, in test_read_on_closed
    self.assertRaises(ValueError, b.peek)
AssertionError: ValueError not raised by peek

----------------------------------------------------------------------
Ran 4 tests in 0.010s

FAILED (failures=2)

After that, I've tested other methods and here's a list of methods that work on closed in _pyio, but raises on _io:

  • readinto1
  • readinto
  • read1
  • peek

Related https://bugs.python.org/issue23796

Is it a bug or a feature? Is it worth fixing?
This clearly looks like a bug to me.

If others confirm, I have a patch ready :)

  • PR: gh-98999: Raise ValueError in _pyio on closed buffers #99009

Activity

  1. sobolevn
    added
    type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error
    stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory
    topic-IO
    on Nov 2, 2022

  2. corona10 commented on Nov 2, 2022

    @corona10
    corona10
    on Nov 2, 2022
    Member
    More actions

    @sobolevn It is worth to fix it, Please send the patch.

  3. sobolevn
    added a commit that references this issue on Nov 2, 2022

    pythongh-98999: Raise `ValueError` in `_pyio` on closed buffers

    597ccf8

  4. sobolevn commented on Nov 2, 2022

    @sobolevn
    sobolevn
    on Nov 2, 2022
    MemberAuthor
    More actions

    Done :)
    Thank you!

  5. corona10
    added a commit that references this issue on Nov 3, 2022

    gh-98999: Raise `ValueError` in `_pyio` on closed buffers (gh-99009)

    2cfcaf5
  6. sobolevn
    closed this as completedon Nov 3, 2022
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