[CRIU] [PATCH v2 5/5] compel: Add nspid, nssid and nspgid fields to struct seize_task_status

[Kirill Tkhai]

On 02.05.2017 12:13, Kirill Tkhai wrote:
> On 29.04.2017 09:12, Andrei Vagin wrote:
>> On Fri, Apr 28, 2017 at 11:03:08PM -0700, Andrei Vagin wrote:
>>> On Tue, Apr 18, 2017 at 06:57:07PM +0300, Kirill Tkhai wrote:
>>>> Some users want them, so add these fields to the structure.
>>>>
>>>> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
>>>> ---
>>>>  compel/include/uapi/infect.h |    4 ++++
>>>>  compel/src/lib/infect.c      |    6 ++++++
>>>>  2 files changed, 10 insertions(+)
>>>>
>>>> diff --git a/compel/include/uapi/infect.h b/compel/include/uapi/infect.h
>>>> index 7b681b0cb..4c6ab413d 100644
>>>> --- a/compel/include/uapi/infect.h
>>>> +++ b/compel/include/uapi/infect.h
>>>> @@ -21,6 +21,10 @@ struct seize_task_status {
>>>>  	int			seccomp_mode;
>>>>  	unsigned long long	shdpnd;
>>>>  	unsigned long long	sigpnd;
>>>> +	size_t			ns_levels;
>>>> +	uint32_t		*nspid;
>>>> +	uint32_t		*nspgid;
>>>> +	uint32_t		*nssid;
>>>
>>> Here is the compel code and now we try to add fields which are
>>> not used in compel. It doesn't look good.
>>
>> Maybe we need to declare a new structure in criu which will encapsulate
>> seize_task_status?
> 
> Look at the description of patch [3/5]. It's explained there, why I go this
> way. A method get_status() of function compel_wait_task() may be called
> twice, and the allocated fields must be freed before the second call.
> 
> Since different methods get_status() may allocate different arguments,
> if we do not go my way, then we need either appropriate free_status()
> methods (which is more complex) or to free the previously allocated
> status in get_status() on the second call (which is ugly).
> 
> I suggest generic method, suitable for everything, which does not make
> the code complicate and which is easily extensible for new fields.
> 
> I don't agree, it looks bad. Also, there is no a rule that a library
> must not contain more methods and interfaces, when it's need for itself.

+ It's why a library is need at all.
  
>>>
>>>
>>>>  	/* Add new members to the bottom and do not change existing */
>>>>  };
>>>>  
>>>> diff --git a/compel/src/lib/infect.c b/compel/src/lib/infect.c
>>>> index 9ade844cf..ab7558a81 100644
>>>> --- a/compel/src/lib/infect.c
>>>> +++ b/compel/src/lib/infect.c
>>>> @@ -190,11 +190,17 @@ static int skip_sigstop(int pid, int nr_signals)
>>>>  /* Init dynamically allocated fields in NULL and do not touch other */
>>>>  static void init_seize_task_status(struct seize_task_status *ss)
>>>>  {
>>>> +	ss->ns_levels = 0;
>>>> +	ss->nspid = ss->nspgid = ss->nssid = NULL;
>>>>  }
>>>>  
>>>>  /* Free dynamically allocated fields in compel_wait_task() and do not touch other */
>>>>  void compel_consume_seize_task_status(struct seize_task_status *ss)
>>>>  {
>>>> +	xfree(ss->nspid);
>>>> +	xfree(ss->nspgid);
>>>> +	xfree(ss->nssid);
>>>> +
>>>>  	init_seize_task_status(ss);
>>>>  }
>>>>  
>>>>