[CRIU] [PATCH 3/3] unix: allow --external unix[ino]:string

[Pavel Emelyanov]

On 01/11/2017 02:59 PM, Ruslan Kuprieiev wrote:
> Doing it on dump adds a benefit of not having to remember anything for 
> restore.
> If this option will be available only on restore, I would have to 
> remember socket ino till
> restore to set up this option, which I'm trying to avoid altogether.
> 
> Can we maybe have this option both on dump and restore?

OK, bet also note that the format --external unix[id]:string is reserved
for the case when the unix socket in question is connect()-ed to the
path $string. So I'd also appreciate if you introduce some ... I don't
know, syntax inside the string so that we could add the functionality
in question later. Would you? :)

-- Pavel

> On 01/11/2017 12:36 PM, Pavel Emelyanov wrote:
>> On 01/10/2017 04:01 PM, Ruslan Kuprieiev wrote:
>>> On dump, if --external unix[ino]:foo is specified, criu will treat
>>> specified unix socket almost the same
>>> way it handles criu service socket. It will dump it as closed and will
>>> put "foo" string into images, to put
>>> that "foo" string into that socket on restore. This is almost identical
>>> to what criu does with service
>>> socket, but instead of putting a Criu_Resp message into it on restore,
>>> it puts an arbitrary string.
>> Ah, I see. I think, that adding a message to send after restore should be
>> a restore-time option and the string in question shouldn't sit in images.
>> Can you tune the patches to make it so?
>>
>>> On 01/10/2017 02:56 PM, Pavel Emelyanov wrote:
>>>> On 01/05/2017 03:42 PM, Ruslan Kuprieiev wrote:
>>>>
>>>> Can you elaborate what this option should do? It's not 100% clear
>>>> from the code.
>>>>
>>>>> Needles to say that it's useful for debug, but this is also
>>>>> very useful when you syncronise checkpoint/restore whith a
>>>>> dumpee using unix socketpair and want it to painlessly
>>>>> receive notification on restore.
>>>>>
>>>>> Signed-off-by: Ruslan Kuprieiev <rkuprieiev at cloudlinux.com>
>>>>> ---
>>>>>    criu/sk-unix.c       | 23 +++++++++++++++++++++--
>>>>>    images/sk-unix.proto |  5 +++++
>>>>>    2 files changed, 26 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/criu/sk-unix.c b/criu/sk-unix.c
>>>>> index 5cbe07a..4527dd6 100644
>>>>> --- a/criu/sk-unix.c
>>>>> +++ b/criu/sk-unix.c
>>>>> @@ -263,6 +263,8 @@ static int dump_one_unix_fd(int lfd, u32 id, const struct fd_parms *p)
>>>>>    	SkOptsEntry *skopts;
>>>>>    	FilePermsEntry *perms;
>>>>>    	FownEntry *fown;
>>>>> +	char buf[PATH_MAX];
>>>>> +	char *ext = NULL;
>>>>>    
>>>>>    	ue = xmalloc(sizeof(UnixSkEntry) +
>>>>>    			sizeof(SkOptsEntry) +
>>>>> @@ -322,6 +324,16 @@ static int dump_one_unix_fd(int lfd, u32 id, const struct fd_parms *p)
>>>>>    		ue->uflags |= USK_SERVICE;
>>>>>    	}
>>>>>    
>>>>> +	/* Same as with service_sk, but for custom sockets */
>>>>> +	snprintf(buf, sizeof(buf), "unix[%u]", ue->peer);
>>>>> +	ext = external_lookup_by_key(buf);
>>>>> +	if (unlikely(!IS_ERR_OR_NULL(ext))) {
>>>>> +		ue->state = TCP_CLOSE;
>>>>> +		ue->peer = 0;
>>>>> +		ue->uflags |= USK_SERVICE;
>>>>> +		ue->stub = (void *)strtok(ext, ":");
>>>>> +	}
>>>>> +
>>>>>    	if (sk->namelen && *sk->name) {
>>>>>    		ue->file_perms = perms;
>>>>>    
>>>>> @@ -1139,8 +1151,15 @@ static int open_unixsk_standalone(struct unix_sk_info *ui)
>>>>>    			return -1;
>>>>>    		}
>>>>>    
>>>>> -		if (send_criu_dump_resp(sks[1], true, true) == -1)
>>>>> -			return -1;
>>>>> +		if (ui->ue->stub) {
>>>>> +			unsigned int l;
>>>>> +			l = strlen(ui->ue->stub);
>>>>> +			if (write(sks[1], ui->ue->stub, l) != l)
>>>>> +				return -1;
>>>>> +		} else {
>>>>> +			if (send_criu_dump_resp(sks[1], true, true) == -1)
>>>>> +				return -1;
>>>>> +		}
>>>>>    
>>>>>    		close(sks[1]);
>>>>>    		sk = sks[0];
>>>>> diff --git a/images/sk-unix.proto b/images/sk-unix.proto
>>>>> index 3026214..4437700 100644
>>>>> --- a/images/sk-unix.proto
>>>>> +++ b/images/sk-unix.proto
>>>>> @@ -48,4 +48,9 @@ message unix_sk_entry {
>>>>>    	 */
>>>>>    	optional string			name_dir	= 14;
>>>>>    	optional bool			deleted		= 15;
>>>>> +
>>>>> +	/*
>>>>> +	 * Stub to put into service socket on restore
>>>>> +	 */
>>>>> +        optional string			stub		= 16;
>>>>>    }
>>>>>
>>> .
>>>
> 
> .
>