1 # Copyright (C) 2016-2020 Free Software Foundation, Inc.
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.
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.
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/>.
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.
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
29 from gdb
.unwinder
import Unwinder
31 class TestUnwinder(Unwinder
):
36 def reset_count (cls
):
43 test
= 'check_undefined_symbol'
46 def set_test (cls
, test
) :
50 Unwinder
.__init
__(self
, "test unwinder")
51 self
.recurse_level
= 0
53 def __call__(self
, pending_frame
):
55 if self
.recurse_level
> 0:
56 gdb
.write("TestUnwinder: Recursion detected - returning early.\n")
59 self
.recurse_level
+= 1
60 TestUnwinder
.inc_count()
62 if TestUnwinder
.test
== 'check_user_reg_pc' :
64 pc
= pending_frame
.read_register('pc')
65 pc_as_int
= int(pc
.cast(gdb
.lookup_type('int')))
66 # gdb.write("In unwinder: pc=%x\n" % pc_as_int)
68 elif TestUnwinder
.test
== 'check_pae_pc' :
70 pc
= gdb
.parse_and_eval('$pc')
71 pc_as_int
= int(pc
.cast(gdb
.lookup_type('int')))
72 # gdb.write("In unwinder: pc=%x\n" % pc_as_int)
74 elif TestUnwinder
.test
== 'check_undefined_symbol' :
77 val
= gdb
.parse_and_eval("undefined_symbol")
79 except Exception as arg
:
82 self
.recurse_level
-= 1
86 gdb
.unwinder
.register_unwinder(None, TestUnwinder(), True)
87 gdb
.write("Python script imported\n")
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