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

   1 # Copyright (C) 2016-2023 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
  32 class TestUnwinder(Unwinder):
  33
  34     count = 0
  35
  36     @classmethod
  37     def reset_count(cls):
  38         cls.count = 0
  39
  40     @classmethod
  41     def inc_count(cls):
  42         cls.count += 1
  43
  44     test = "check_undefined_symbol"
  45
  46     @classmethod
  47     def set_test(cls, test):
  48         cls.test = test
  49
  50     def __init__(self):
  51         Unwinder.__init__(self, "test unwinder")
  52         self.recurse_level = 0
  53
  54     def __call__(self, pending_frame):
  55
  56         if self.recurse_level > 0:
  57             gdb.write("TestUnwinder: Recursion detected - returning early.\n")
  58             return None
  59
  60         self.recurse_level += 1
  61         TestUnwinder.inc_count()
  62
  63         if TestUnwinder.test == "check_user_reg_pc":
  64
  65             pc = pending_frame.read_register("pc")
  66             pc_as_int = int(pc.cast(gdb.lookup_type("int")))
  67             # gdb.write("In unwinder: pc=%x\n" % pc_as_int)
  68
  69         elif TestUnwinder.test == "check_pae_pc":
  70
  71             pc = gdb.parse_and_eval("$pc")
  72             pc_as_int = int(pc.cast(gdb.lookup_type("int")))
  73             # gdb.write("In unwinder: pc=%x\n" % pc_as_int)
  74
  75         elif TestUnwinder.test == "check_undefined_symbol":
  76
  77             try:
  78                 val = gdb.parse_and_eval("undefined_symbol")
  79
  80             except Exception as arg:
  81                 pass
  82
  83         self.recurse_level -= 1
  84
  85         return None
  86
  87
  88 gdb.unwinder.register_unwinder(None, TestUnwinder(), True)
  89 gdb.write("Python script imported\n")