New submission from Petr Viktorin:
A Python int larger than a C int but smaller than a C long is silently
truncated to int when passed to a ctypes function without C type information
attached.
Ints longer than C long fail with an OverflowError; I believe the same should
happen for numbers that don't fit in a C int.
Reproducer (for 64-bit systems):
from ctypes import cdll, ArgumentError
libc = cdll.LoadLibrary("libc.so.6")
# Silently truncated
libc.printf(b"%x\n", 0x1234567890)
try:
# OverflowError raised
libc.printf(b"%x\n", 2 ** 64)
except ArgumentError as e:
print(e)
see callproc.c, function ConvParam, after the PyLong_Check.
----------
components: ctypes
messages: 247565
nosy: encukou
priority: normal
severity: normal
status: open
title: ctypes silently truncates ints larger than C int
versions: Python 2.7, Python 3.4, Python 3.5, Python 3.6
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Python tracker <[email protected]>
<http://bugs.python.org/issue24747>
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