[CRIU] [PATCH v2 03/15] sysctl: add req->has to mark successful sysctl_op request

[Pavel Tikhomirov]

On 04/21/2016 05:09 PM, Pavel Emelyanov wrote:
> On 04/20/2016 05:42 PM, Pavel Tikhomirov wrote:
>> must be carefull allocating memory for sysctl_req as trash values
>> can cause segmentation fault
>>
>> Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
>> ---
>>   criu/include/sysctl.h | 1 +
>>   criu/sysctl.c         | 8 ++++++++
>>   2 files changed, 9 insertions(+)
>>
>> diff --git a/criu/include/sysctl.h b/criu/include/sysctl.h
>> index b949a40..9ee93c6 100644
>> --- a/criu/include/sysctl.h
>> +++ b/criu/include/sysctl.h
>> @@ -6,6 +6,7 @@ struct sysctl_req {
>>   	void	*arg;
>>   	int	type;
>>   	int	flags;
>> +	int	*has;
>
> I'd better report back some bit (in case of sysctl was missing) in the flags field.

In case of CTL_READ we fortunately have identic mapping conf[i] to 
req[i], so I can write conf[i].has_ fields checking req[i].flags, OK.

>
>>   };
>>
>>   extern int sysctl_op(struct sysctl_req *req, size_t nr_req, int op, unsigned int ns);
>> diff --git a/criu/sysctl.c b/criu/sysctl.c
>> index 21ae4ce..bd584bd 100644
>> --- a/criu/sysctl.c
>> +++ b/criu/sysctl.c
>> @@ -261,6 +261,10 @@ static int __userns_sysctl_op(void *arg, int proc_fd, pid_t pid)
>>   			goto out;
>>   		}
>>
>> +		if (req->has)
>> +			/* sysctl in question exists */
>> +			*req->has = 1;
>> +
>>   		/* save a pointer to the req, so we don't need to recompute its
>>   		 * location
>>   		 */
>> @@ -371,6 +375,10 @@ static int __nonuserns_sysctl_op(struct sysctl_req *req, size_t nr_req, int op)
>>   			goto out;
>>   		}
>>
>> +		if (req->has)
>> +			/* sysctl in question exists */
>> +			 *req->has = 1;
>> +
>>   		ret = do_sysctl_op(fd, req, op);
>>   		if (ret)
>>   			goto out;
>>
>

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.