[New-bugs-announce] [issue32745] ctypes string pointer fields should accept embedded null characters

[Thomas Heller]

New submission from Thomas Heller <theller at ctypes.org>:

ctypes Structure fields of type c_char_p or c_wchar_p used to accept strings with embedded null characters.  I noticed that Python 3.6.4 does refuse them.  It seems this has been changed in recent version(s).

There ARE use-cases for this:  The Windows-API OPENFILENAME structure is one example.  The Microsoft docs for the lpstrFilter field:

"""
lpstrFilter

    Type: LPCTSTR

    A buffer containing pairs of null-terminated filter strings. The last string in the buffer must be terminated by two NULL characters.
"""

I have attached a simple script which demonstrates this new behaviour; the output with Python 3.6.4 is this:

Traceback (most recent call last):
  File "nullchars.py", line 8, in <module>
    t.unicode = u"foo\0bar"
ValueError: embedded null character

----------
components: ctypes
files: nullchars.py
keywords: 3.6regression
messages: 311462
nosy: theller
priority: normal
severity: normal
status: open
title: ctypes string pointer fields should accept embedded null characters
versions: Python 3.6
Added file: https://bugs.python.org/file47420/nullchars.py

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<https://bugs.python.org/issue32745>
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