gdb/testsuite/gdb.python/py-recurse-unwind.py

   1 # Copyright (C) 2016 Free Software Foundation, Inc.
   2
   3 # This program is free software; you can redistribute it and/or modify
   4 # it under the terms of the GNU General Public License as published by
   5 # the Free Software Foundation; either version 3 of the License, or
   6 # (at your option) any later version.
   7 #
   8 # This program is distributed in the hope that it will be useful,
   9 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 # GNU General Public License for more details.
  12 #
  13 # You should have received a copy of the GNU General Public License
  14 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15
  16 # This unwinder never does any unwinding.  It'll (pretend to) "sniff"
  17 # the frame and ultimately return None, indicating that actual unwinding
  18 # should be performed by some other unwinder.
  19 #
  20 # But, prior to returning None, it will attempt to obtain the value
  21 # associated with a symbol via a call to gdb.parse_and_eval().  In
  22 # the course of doing this evaluation, GDB will potentially access
  23 # some frames, leading to the possibility of a recursive invocation of
  24 # this unwinder.  If that should happen, code contained herein detects
  25 # that and prints a message which will cause some of the associated
  26 # tests to FAIL.
  27
  28 import gdb
  29 from gdb.unwinder import Unwinder
  30
  31 class TestUnwinder(Unwinder):
  32
  33     count = 0
  34
  35     @classmethod
  36     def reset_count (cls):
  37         cls.count = 0
  38
  39     @classmethod
  40     def inc_count (cls):
  41         cls.count += 1
  42
  43     def __init__(self):
  44         Unwinder.__init__(self, "test unwinder")
  45         self.recurse_level = 0
  46
  47     def __call__(self, pending_frame):
  48
  49
  50         if self.recurse_level > 0:
  51             gdb.write("TestUnwinder: Recursion detected - returning early.\n")
  52             return None
  53
  54         self.recurse_level += 1
  55         TestUnwinder.inc_count()
  56
  57         try:
  58             val = gdb.parse_and_eval("undefined_symbol")
  59
  60         except Exception as arg:
  61             pass
  62
  63         self.recurse_level -= 1
  64
  65         return None
  66
  67 gdb.unwinder.register_unwinder(None, TestUnwinder(), True)
  68 gdb.write("Python script imported\n")