When we create a Nftables instance against an older library version,
we might not find a symbol and fail with an exception when initializing
the context object.
Then, __del__() is still called, but resulting in a second exception
because self.__ctx is not set. Avoid that second exception.
$ python -c 'import nftables; nftables.Nftables()'
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/data/src/nftables/py/nftables.py", line 90, in __init__
self.nft_ctx_input_get_flags = lib.nft_ctx_input_get_flags
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib64/python3.11/ctypes/__init__.py", line 389, in __getattr__
func = self.__getitem__(name)
^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib64/python3.11/ctypes/__init__.py", line 394, in __getitem__
func = self._FuncPtr((name_or_ordinal, self))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: /lib64/libnftables.so.1: undefined symbol: nft_ctx_input_get_flags
Exception ignored in: <function Nftables.__del__ at 0x7f6315a2c540>
Traceback (most recent call last):
File "/data/src/nftables/py/nftables.py", line 166, in __del__
self.nft_ctx_free(self.__ctx)
^^^^^^^^^^^^^^^^^
AttributeError: 'Nftables' object has no attribute 'nft_ctx_free'
Signed-off-by: Thomas Haller <thaller@xxxxxxxxxx>
Reviewed-by: Phil Sutter <phil@xxxxxx>
---
py/src/nftables.py | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/py/src/nftables.py b/py/src/nftables.py
index 68fcd7dd103c..b1186781ab5c 100644
--- a/py/src/nftables.py
+++ b/py/src/nftables.py
@@ -74,6 +74,8 @@ class Nftables:
is requested from the library and buffering of output and error streams
is turned on.
"""
+ self.__ctx = None
+
lib = cdll.LoadLibrary(sofile)
### API function definitions
@@ -150,7 +152,9 @@ class Nftables:
self.nft_ctx_buffer_error(self.__ctx)
def __del__(self):
- self.nft_ctx_free(self.__ctx)
+ if self.__ctx is not None:
+ self.nft_ctx_free(self.__ctx)
+ self.__ctx = None
def __get_output_flag(self, name):
flag = self.output_flags[name]
--
2.41.0
