[issue21363] io.TextIOWrapper always closes wrapped files
Marten H. van Kerkwijk added the comment: In astropy we are now working around the auto-closing of the underlying stream in TextIOWrapper by subclassing and overriding `__del__` to detach [1]. It would seem more elegant if `TestIOWrapper` (and really, `BufferedReader`) could gain an `closefd` argument, just like `open` has, which is `True` by default. p.s. Do let me know if it is better to open a new issue. [1] https://github.com/astropy/astropy/pull/11809 -- nosy: +mhvk type: -> enhancement ___ Python tracker <https://bugs.python.org/issue21363> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40720] accessing mmap of file that is overwritten causes bus error
Marten H. van Kerkwijk added the comment: I should probably have added that the bus error happens on linux. On Windows, the opening of the file for writing leads to an error, as the file is still opened for reading inside the mmap. -- ___ Python tracker <https://bugs.python.org/issue40720> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40720] accessing mmap of file that is overwritten causes bus error
New submission from Marten H. van Kerkwijk :
While debugging a strange failure with tests and np.memmap, I realized that the
following direct use of mmap reliably leads to a bus error. Here, obviously
mmap'ing a file, closing it, opening the file for writing but not writing
anything, and then again accessing the mmap is not something one should do (but
a test case did it anyway), but it would nevertheless be nice to avoid a crash!
```
import mmap
with open('test.dat', 'wb') as fh:
fh.write(b'abcdefghijklmnopqrstuvwxyz')
with open('test.dat', 'rb') as fh:
mm = mmap.mmap(fh.fileno(), 0, access=mmap.ACCESS_READ)
with open('test.dat', 'wb') as fh:
pass # Note: if something is written, then I get no bus error.
mm[2]
```
--
components: Library (Lib)
messages: 369543
nosy: mhvk
priority: normal
severity: normal
status: open
title: accessing mmap of file that is overwritten causes bus error
type: crash
versions: Python 3.8
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