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[Bug python/10344] Pretty printers that call into inferior could crash GDB
- From: "pmuldoon at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: gdb-prs at sourceware dot org
- Date: 24 Sep 2009 16:15:42 -0000
- Subject: [Bug python/10344] Pretty printers that call into inferior could crash GDB
- References: <20090629213421.10344.ppluzhnikov@google.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From pmuldoon at redhat dot com 2009-09-24 16:15 -------
Increasing the MAX_UI_OUT_LEVELS will fix the bug as reported, but it will not
help when a situation occurs where the the printers can end up recursing (and
gobbling up the ui levels). Example.
--- cut --- t2.cc ---
#include <stdio.h>
struct Foo;
struct Recurse;
struct Foo {
Foo() : p(0) { }
const char *print(Recurse b) const;
char **p;
};
struct Recurse {
Recurse (): p (0) { }
const char *crash(Foo f) const;
char **p;
};
const char *Recurse::crash(Foo f) const
{
return *p; // crash as well
}
const char *Foo::print(Recurse b) const
{
return *p; // crash!
}
char **bar(Foo f)
{
return f.p;
}
int main()
{
Foo f;
Recurse b;
bar(f);
return 0;
}
--- cut --- t2.py ---
# Pretty printer for Foo, which calls into inferior
import gdb
class FooPrinter:
def __init__(self, val):
self.val = val
def to_string(self):
x = self.val.address
return gdb.parse_and_eval('Foo::print(%s,f)' % str(x))
class RecursePrinter:
def __init__(self, val):
self.val = val
def to_string(self):
x = self.val.address
return gdb.parse_and_eval('Recurse::crash(%s,b)' % str(x))
def lookup(val):
if str(val.type) == "Foo":
return FooPrinter(val)
else:
if str(val.type) == "Recurse":
return RecursePrinter(val)
else:
return None
gdb.pretty_printers = [ lookup ]
I also increased the max MAX_UI_OUT_LEVELS to 15. But it does not matter, it can
be 1000, the result is the same.
-- Test case
./gdb -ex 'source /home/pmuldoon/pp/t.py' -ex 'break bar' -ex 'run'
/home/pmuldoon/pp/t2
Output
Breakpoint 1, bar (f=
Program received signal SIGSEGV, Segmentation fault.
0x000000000040057f in Foo::print (this=0x7fffffffe170, b=
Program received signal SIGSEGV, Segmentation fault.
0x0000000000400567 in Recurse::crash (this=0x7fffffffe0e0, f=
Program received signal SIGSEGV, Segmentation fault.
0x000000000040057f in Foo::print (this=0x7fffffffe050, b=
Program received signal SIGSEGV, Segmentation fault.
0x0000000000400567 in Recurse::crash (
../../archer/gdb/ui-out.c:129: internal-error: push_level: Assertion
`uiout->level >= 0 && uiout->level < MAX_UI_OUT_LEVELS' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) q
--
http://sourceware.org/bugzilla/show_bug.cgi?id=10344
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