[PR,python/21460] Avoid segfault during Python cleanup

  Rationale for the patch and repro instructions are explained in the bug.

I don't have any copyright assignment on file but this really should be trivial enough to avoid that, I think.

gdb/Changelog:
2017-05-25  paul cannon  <paul@thepaul.org>

	python/21460
	* python.c (gdbpy_set_quit_flag) Check Py_IsInitialized() before calling PyErr_SetInterrupt(), as Python may be shutting down already.

---
 gdb/python/python.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

-- 
2.7.4
  

Hi Paul,

On 2017-05-25 18:26, paul cannon wrote:
> Rationale for the patch and repro instructions are explained in the 
> bug.

Thanks for the patch, and sorry for the little delay in processing it.  
I think the code in itself is good.  I'll just point out a few things to 
fix.

> I don't have any copyright assignment on file but this really should
> be trivial enough to avoid that, I think.

That's what I think too.  Do you intend to contribute to GDB regularly?  
If so we can get you write access to the repo.  If not, I can push the 
patch on your behalf (when the issues I mentioned are fixed).

> gdb/Changelog:
> 2017-05-25  paul cannon  <paul@thepaul.org>

Should your name have capital letters :) ?

> 
> 	python/21460
> 	* python.c (gdbpy_set_quit_flag) Check Py_IsInitialized() before
> calling PyErr_SetInterrupt(), as Python may be shutting down already.

The ChangeLog should only contain "what" changed and not "why".  So just 
the first part:

   Check Py_IsInitialized() before calling PyErr_SetInterrupt().

is sufficient.  However, the why should be contained in the commit 
message.  You did a good job at explaining the problem in the bug you 
filed, so I think you could just take that and put it in the commit log 
(and massage it a bit if needed).

> 
> ---
>  gdb/python/python.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/gdb/python/python.c b/gdb/python/python.c
> index be92f36..c6a8c17 100644
> --- a/gdb/python/python.c
> +++ b/gdb/python/python.c
> @@ -247,7 +247,10 @@ gdbpy_enter::~gdbpy_enter ()
>  static void
>  gdbpy_set_quit_flag (const struct extension_language_defn *extlang)
>  {
> -  PyErr_SetInterrupt ();
> +  if (Py_IsInitialized ())
> +    {
> +      PyErr_SetInterrupt ();
> +    }

Drop the braces for a single line body:

   if (Py_IsInitialized ())
     PyErr_SetInterrupt ();

>  }
>  
>  /* Return true if the quit flag has been set, false otherwise.  */
> -- 
> 2.7.4

Thanks!

Simon
  

On Sunday, June 11 2017, Simon Marchi wrote:

>>
>> 	python/21460
>> 	* python.c (gdbpy_set_quit_flag) Check Py_IsInitialized() before
>> calling PyErr_SetInterrupt(), as Python may be shutting down already.
>
> The ChangeLog should only contain "what" changed and not "why".  So
> just the first part:
>
>   Check Py_IsInitialized() before calling PyErr_SetInterrupt().
>
> is sufficient.  However, the why should be contained in the commit
> message.  You did a good job at explaining the problem in the bug you
> filed, so I think you could just take that and put it in the commit
> log (and massage it a bit if needed).

Also, I think it's worth mentioning that the ChangeLog lines shouldn't
exceed 76 chars (soft limit).  And the file 'python.c' is inside the
python/ directory.  So a good example would be:

yyyy-mm-dd  Name  <email>

	PR python/21460
	* python/python.c: Check Py_IsInitialized() before calling
	PyErr_SetInterrupt().

Cheers,