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gh-143010: Prevent a TOCTOU issue by only calling open once #143011

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Merged
bitdancer merged 3 commits into from
Dec 22, 2025
Merged

gh-143010: Prevent a TOCTOU issue by only calling open once #143011

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gh-143010: Prevent a TOCTOU issue by gh-143010: Prevent a TOCTOU issu…
AZero13 Dec 20, 2025
879f581
Fix News
AZero13 Dec 21, 2025
7b1b9f2
Update 2025-12-20-01-49-02.gh-issue-143010._-SWX0.rst
AZero13 Dec 21, 2025
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6 changes: 1 addition & 5 deletions Lib/mailbox.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2181,11 +2181,7 @@ def _unlock_file(f):

def _create_carefully(path):
"""Create a file if it doesn't exist and open for reading and writing."""
fd = os.open(path, os.O_CREAT | os.O_EXCL | os.O_RDWR, 0o666)
try:
return open(path, 'rb+')
finally:
os.close(fd)
return open(path, 'xb+')

def _create_temporary(path):
"""Create a temp file based on path and open for reading and writing."""
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2025-12-20-01-49-02.gh-issue-143010._-SWX0.rst
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@@ -0,0 +1 @@
mailbox: Fixed a bug in :mod:mailbox where the precise timing of an external event could result in the library opening an existing file instead of a file it expected to create.
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