[CRIU] [PATCH 1/3]v3 libcriu: criu_dump_me() and library header

[Ruslan Kuprieiev]

On 08/30/2013 12:25 AM, Pavel Emelyanov wrote:
> On 08/30/2013 12:15 AM, Ruslan Kuprieiev wrote:
>> On 08/30/2013 12:04 AM, Pavel Emelyanov wrote:
>>> On 08/29/2013 11:44 PM, Ruslan Kuprieiev wrote:
>>>> On 08/29/2013 11:21 PM, Pavel Emelyanov wrote:
>>>>> On 08/29/2013 11:08 PM, Ruslan Kuprieiev wrote:
>>>>>> Hi!
>>>>>>
>>>>>> Patch 1\3 contains criu_dump_me() for library and library header.
>>>>>>            -- criu_dump_me() gets an argument of  type struct criu_dump_args
>>>>>> from user program,
>>>>>>              processes it and sends request to criu through unix domain
>>>>>> socket.
>>>>>>              Then, it gets flag from criu and returns it back to program.
>>>>>>            -- libcriu.h contains definitions of flags, struct
>>>>>> criu_dump_args etc.
>>>>>>               So, it is to be used in user program.
>>>>>>
>>>>>> Signed-off-by: Ruslan Kuprieiev <kupruser at gmail.com>
>>>>>>
>>>>>> +int criu_dump_me(struct criu_dump_args *arg)
>>>>>> +{
>>>>>> +	int socket_fd;
>>>>>> +	int ret, c;
>>>>>> +	struct sockaddr_un server_addr;
>>>>>> +	socklen_t server_addr_len;
>>>>> I'm trying to imagine how this all should work when a user that has some
>>>>> 3rd party app linked with v0.7's libcriu.so upgrades criu and has v0.8's
>>>>> one with criu_dump_args extended.
>>>>>
>>>>> In his software the new "tail" of this structure is not seen (as hi had it
>>>>> compiled against old headers with shorted struct). Thus we'd see uninitialized
>>>>> data here in the library and have no idea how to check this.
>>>>>
>>>>> I think we need the criu_alloc_args() call that will call malloc() with
>>>>> proper size and zeroify the whole structure.
>> Maybe, criu_alloc_args() should malloc "struct criu_dump_args *args" and
>> return "args" , witch will be like "opts" in crtools?
> They cannot be equal, since there's a couple of things, that are missing
> from opts, but are required on args. But yes -- they mostly overlap.
I'm not about сomposition, i'm about organization=).
I mean, make "args" pointer in libcriu.h, and use only it in libcriu.

Or,maybe, do not provide access to structure itself to user program at all?
Make functions criu_set_flags(int flags), criu_set_dir_fd(int fd) etc?
Maybe it will be safer?
>>>> Ok, i will fix it.
>>>> By the way, maybe i should add version check? (maybe, after i fix what i
>>>> should fix, and first patch will be applied)
>>>> Correct me, if i'm mistaken.
>>>> I should add criu_check_version(), that must be called right after
>>>> connect to socket.
>>>> It should send version of library and recv "true" if
>>>> libversion<=criuversion or "false" if libversion>criuversion.
>>>> Also add some CRIU_OLD_VERSION macro to return for "false" case.
>>>>
>>>> .
>>>>
>>> yup
>> .
>>
>