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# Copyright (C) 2016-2020 Free Software Foundation, Inc.
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# This unwinder never does any unwinding. It'll (pretend to) "sniff"
# the frame and ultimately return None, indicating that actual unwinding
# should be performed by some other unwinder.
#
# But, prior to returning None, it will attempt to obtain the value
# associated with a symbol via a call to gdb.parse_and_eval(). In
# the course of doing this evaluation, GDB will potentially access
# some frames, leading to the possibility of a recursive invocation of
# this unwinder. If that should happen, code contained herein detects
# that and prints a message which will cause some of the associated
# tests to FAIL.
import gdb
from gdb.unwinder import Unwinder
class TestUnwinder(Unwinder):
count = 0
@classmethod
def reset_count (cls):
cls.count = 0
@classmethod
def inc_count (cls):
cls.count += 1
test = 'check_undefined_symbol'
@classmethod
def set_test (cls, test) :
cls.test = test
def __init__(self):
Unwinder.__init__(self, "test unwinder")
self.recurse_level = 0
def __call__(self, pending_frame):
if self.recurse_level > 0:
gdb.write("TestUnwinder: Recursion detected - returning early.\n")
return None
self.recurse_level += 1
TestUnwinder.inc_count()
if TestUnwinder.test == 'check_user_reg_pc' :
pc = pending_frame.read_register('pc')
pc_as_int = int(pc.cast(gdb.lookup_type('int')))
# gdb.write("In unwinder: pc=%x\n" % pc_as_int)
elif TestUnwinder.test == 'check_pae_pc' :
pc = gdb.parse_and_eval('$pc')
pc_as_int = int(pc.cast(gdb.lookup_type('int')))
# gdb.write("In unwinder: pc=%x\n" % pc_as_int)
elif TestUnwinder.test == 'check_undefined_symbol' :
try:
val = gdb.parse_and_eval("undefined_symbol")
except Exception as arg:
pass
self.recurse_level -= 1
return None
gdb.unwinder.register_unwinder(None, TestUnwinder(), True)
gdb.write("Python script imported\n")
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