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imaplib.Time2Internaldate raises IndexError instead of ValueError on an empty string #153854
Description
Bug report
Bug description:
imaplib.Time2Internaldate is documented to raise ValueError for input that is not of a known type, and its own final branch is raise ValueError("date_time not of a known type"). However, the string branch subscripts the value before that check:
elif isinstance(date_time, str) and (date_time[0],date_time[-1]) == ('"','"'):so an empty string escapes as a bare IndexError instead:
>>> import imaplib
>>> imaplib.Time2Internaldate('')
Traceback (most recent call last):
...
IndexError: string index out of range
>>> imaplib.Time2Internaldate('x') # non-empty unquoted string is fine
Traceback (most recent call last):
...
ValueError: date_time not of a known typeThe fix is to use slices so the comparison is simply false for an empty string and control falls through to the intended ValueError:
elif isinstance(date_time, str) and (date_time[:1], date_time[-1:]) == ('"', '"'):Behavior for all other inputs is unchanged. Related: gh-86165 recently fixed a different crash in this same function. I have a PR ready with the fix, a regression test, and a NEWS entry.
CPython versions tested on:
3.12, CPython main branch
Operating systems tested on:
No response
Activity
pythongh-153854: Fix imaplib.Time2Internaldate crash on an empty string
pythongh-153854: Add regression test for Time2Internaldate('')
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
pythongh-153854: Raise ValueError from imaplib.Time2Internaldate on e…
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
pythongh-153854: Raise ValueError from imaplib.Time2Internaldate on e…
pythongh-153854: Add NEWS entry
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate
Merge branch 'main' into fix-pythongh-153854-imaplib-time2internaldate