From df4447e4c43e105bd6366081a07447506506f78b Mon Sep 17 00:00:00 2001 From: Andrew Burgess Date: Fri, 10 Mar 2023 10:28:21 +0000 Subject: [PATCH] gdb/python: remove Py_TPFLAGS_BASETYPE from gdb.UnwindInfo It is not currently possible to directly create gdb.UnwindInfo instances, they need to be created by calling gdb.PendingFrame.create_unwind_info so that the newly created UnwindInfo can be linked to the pending frame. As such there's no tp_init method defined for UnwindInfo. A consequence of all this is that it doesn't really make sense to allow sub-classing of gdb.UnwindInfo. Any sub-class can't call the parents __init__ method to correctly link up the PendingFrame object (there is no parent __init__ method). And any instances that sub-classes UnwindInfo but doesn't call the parent __init__ is going to be invalid for use in GDB. This commit removes the Py_TPFLAGS_BASETYPE flag from the UnwindInfo class, which prevents the class being sub-classed. Then I've added a test to check that this is indeed prevented. Any functional user code will not have any issues with this change. Reviewed-By: Tom Tromey --- gdb/python/py-unwind.c | 2 +- gdb/testsuite/gdb.python/py-unwind.exp | 17 +++++++++++++++++ 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/gdb/python/py-unwind.c b/gdb/python/py-unwind.c index 1e94c243163..432a26a760a 100644 --- a/gdb/python/py-unwind.c +++ b/gdb/python/py-unwind.c @@ -1097,7 +1097,7 @@ PyTypeObject unwind_info_object_type = 0, /* tp_getattro */ 0, /* tp_setattro */ 0, /* tp_as_buffer */ - Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */ + Py_TPFLAGS_DEFAULT, /* tp_flags */ "GDB UnwindInfo object", /* tp_doc */ 0, /* tp_traverse */ 0, /* tp_clear */ diff --git a/gdb/testsuite/gdb.python/py-unwind.exp b/gdb/testsuite/gdb.python/py-unwind.exp index 7e6ac9a8623..d65b8447525 100644 --- a/gdb/testsuite/gdb.python/py-unwind.exp +++ b/gdb/testsuite/gdb.python/py-unwind.exp @@ -211,3 +211,20 @@ check_for_fixed_backtrace \ "check backtrace to validate all information" gdb_test_no_output "python check_all_frame_information_matched()" + +# Check we can't sub-class from gdb.UnwindInfo. +gdb_test_multiline "Sub-class gdb.UnwindInfo " \ + "python" "" \ + "class my_unwind_info(gdb.UnwindInfo):" "" \ + " def __init__(self):" "" \ + " pass" "" \ + "end" \ + [multi_line \ + "TypeError: type 'gdb\\.UnwindInfo' is not an acceptable base type" \ + "Error while executing Python code\\."] + +# Check we can't directly instantiate a gdb.UnwindInfo. +gdb_test "python uw = gdb.UnwindInfo()" \ + [multi_line \ + "TypeError: cannot create 'gdb\\.UnwindInfo' instances" \ + "Error while executing Python code\\."] -- 2.30.2