Re: [RFA] PR python/18565 - make Frame.function work for inline frames

Tom Tromey
2016-08-03T15:14:18Z

>>>>> "Yao" == Yao Qi <qiyaoltc@gmail.com> writes:

>> In any case, IMO this would be the subject of a separate patch.

Yao> This is the prerequisite of Tom's patch, no? It guarantees that *FUNNAME
Yao> is not allocated if exception is thrown, otherwise *FUNAME is allocated.
Yao> Tom's patch relies on this behaviour.

Yao> I am OK with Tom's original patch, but we need to fix find_frame_funname
Yao> first.

Here's a patch. Please review.

I'd like to check this and the other into the 7.12 branch as well.

Tom

commit d10153cfc6cb319a75ceb3e3d34ac30efa17e518
Author: Tom Tromey <tom@tromey.com>
Date: Wed Aug 3 08:27:56 2016 -0600

Avoid potential memory leak in find_frame_funname

The PR 18565 thread pointed out that, if cp_remove_params can throw
(we aren't quite sure), then find_frame_funname could leak some
memory. This patch avoids any potential issue by rearranging some
code in find_frame_funname.

Built and regtested on x86-64 Fedora 24.

2016-08-03 Tom Tromey <tom@tromey.com>

* stack.c (find_frame_funname): Avoid any possible leak in case
cp_remove_params can throw.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 6b2fb9c..48ecd67 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
2016-08-03 Tom Tromey <tom@tromey.com>

+ * stack.c (find_frame_funname): Avoid any possible leak in case
+ cp_remove_params can throw.
+
+2016-08-03 Tom Tromey <tom@tromey.com>
+
* NEWS: Mention new Python breakpoint events.

2016-08-02 Tom Tromey <tom@tromey.com>
diff --git a/gdb/stack.c b/gdb/stack.c
index b9e74df..e890949 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -1101,7 +1101,8 @@ find_frame_funname (struct frame_info *frame, char **funname,
}
else
{
- *funname = xstrdup (SYMBOL_PRINT_NAME (func));
+ const char *print_name = SYMBOL_PRINT_NAME (func);
+
*funlang = SYMBOL_LANGUAGE (func);
if (funcp)
*funcp = func;
@@ -1112,14 +1113,17 @@ find_frame_funname (struct frame_info *frame, char **funname,
stored in the symbol table, but we stored a version
with DMGL_PARAMS turned on, and here we don't want to
display parameters. So remove the parameters. */
- char *func_only = cp_remove_params (*funname);
+ char *func_only = cp_remove_params (print_name);

if (func_only)
- {
- xfree (*funname);
- *funname = func_only;
- }
+ *funname = func_only;
}
+
+ /* If we didn't hit the C++ case above, set *funname here.
+ This approach is taken to avoid having to install a
+ cleanup in case cp_remove_params can throw. */
+ if (*funname == NULL)
+ *funname = xstrdup (print_name);
}
}
else