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

[Pavel Emelyanov]

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;
>>>   }
>>>
> 
> .
>