[CRIU] [PATCH 1/3] service: allow to execute page-server as a child process

[Andrei Vagin]

On Tue, Apr 25, 2017 at 12:13:32PM +0300, Pavel Emelyanov wrote:
> On 04/25/2017 12:37 AM, Andrei Vagin wrote:
> > From: Andrei Vagin <avagin at virtuozzo.com>
> 
> How is it executed now? Not as a child?

as a daemon

> 
> > In this case we can wait it and get an exit code.
> > 
> > For example, it will be useful for p.haul where one connection
> > is used several times, so we need a way how to understand  that
> > page-server exited unexpectedly.
> > 
> > Signed-off-by: Andrei Vagin <avagin at virtuozzo.com>
> > ---
> >  criu/cr-service.c | 85 ++++++++++++++++++++++++++++++++++++++++++-------------
> >  images/rpc.proto  |  8 ++++++
> >  2 files changed, 74 insertions(+), 19 deletions(-)
> > 
> > diff --git a/criu/cr-service.c b/criu/cr-service.c
> > index d59ab8b..515d040 100644
> > --- a/criu/cr-service.c
> > +++ b/criu/cr-service.c
> > @@ -710,7 +710,7 @@ struct ps_info {
> >  	unsigned short port;
> >  };
> >  
> > -static int start_page_server_req(int sk, CriuOpts *req)
> > +static int start_page_server_req(int sk, CriuOpts *req, bool daemon_mode)
> >  {
> >  	int ret = -1, pid, start_pipe[2];
> >  	ssize_t count;
> > @@ -735,35 +735,46 @@ static int start_page_server_req(int sk, CriuOpts *req)
> >  
> >  		pr_debug("Starting page server\n");
> >  
> > -		pid = cr_page_server(true, false, start_pipe[1]);
> > +		if (!daemon_mode) {
> > +			count = write(start_pipe[1], &info, sizeof(info));
> > +			if (count != sizeof(info))
> > +				goto out_ch;
> > +		}
> > +
> > +		pid = cr_page_server(daemon_mode, false, start_pipe[1]);
> >  		if (pid < 0)
> >  			goto out_ch;
> >  
> > -		info.pid = pid;
> > -		info.port = opts.port;
> > +		if (daemon_mode) {
> > +			info.pid = pid;
> > +			info.port = opts.port;
> >  
> > -		count = write(start_pipe[1], &info, sizeof(info));
> > -		if (count != sizeof(info))
> > -			goto out_ch;
> > +			count = write(start_pipe[1], &info, sizeof(info));
> > +			if (count != sizeof(info))
> > +				goto out_ch;
> > +		}
> >  
> >  		ret = 0;
> >  out_ch:
> > -		if (ret < 0 && pid > 0)
> > +		if (daemon_mode && ret < 0 && pid > 0)
> >  			kill(pid, SIGKILL);
> >  		close(start_pipe[1]);
> >  		exit(ret);
> >  	}
> >  
> >  	close(start_pipe[1]);
> > -	wait(&ret);
> > -	if (WIFEXITED(ret)) {
> > -		if (WEXITSTATUS(ret)) {
> > -			pr_err("Child exited with an error\n");
> > +
> > +	if (daemon_mode) {
> > +		wait(&ret);
> > +		if (WIFEXITED(ret)) {
> > +			if (WEXITSTATUS(ret)) {
> > +				pr_err("Child exited with an error\n");
> > +				goto out;
> > +			}
> > +		} else {
> > +			pr_err("Child wasn't terminated normally\n");
> >  			goto out;
> >  		}
> > -	} else {
> > -		pr_err("Child wasn't terminated normally\n");
> > -		goto out;
> >  	}
> >  
> >  	count = read(start_pipe[0], &info, sizeof(info));
> > @@ -771,11 +782,15 @@ out_ch:
> >  	if (count != sizeof(info))
> >  		goto out;
> >  
> > +	if (daemon_mode) {
> > +		ps.pid = info.pid;
> > +		ps.has_port = true;
> > +		ps.port = info.port;
> > +	} else
> > +		ps.pid = pid;
> > +
> >  	success = true;
> >  	ps.has_pid = true;
> > -	ps.pid = info.pid;
> > -	ps.has_port = true;
> > -	ps.port = info.port;
> >  	resp.ps = &ps;
> >  
> >  	pr_debug("Page server started\n");
> > @@ -802,6 +817,9 @@ static int chk_keepopen_req(CriuReq *msg)
> >  	if (msg->type == CRIU_REQ_TYPE__PAGE_SERVER)
> >  		/* This just fork()-s so no leaks */
> >  		return 0;
> > +	if (msg->type == CRIU_REQ_TYPE__PAGE_SERVER_CHLD)
> > +		/* This just fork()-s so no leaks */
> > +		return 0;
> >  	else if (msg->type == CRIU_REQ_TYPE__CPUINFO_DUMP ||
> >  		 msg->type == CRIU_REQ_TYPE__CPUINFO_CHECK)
> >  		return 0;
> > @@ -946,6 +964,29 @@ out:
> >  	return send_criu_msg(sk, &resp);
> >  }
> >  
> > +static int handle_wait_pid(int sk, int pid)
> > +{
> > +	CriuResp resp = CRIU_RESP__INIT;
> > +	bool success = false;
> > +	int status;
> > +
> > +	if (waitpid(pid, &status, 0) == -1) {
> > +		resp.cr_errno = errno;
> > +		pr_perror("Unable to wait %d", pid);
> > +		goto out;
> > +	}
> > +
> > +	resp.status = status;
> > +	resp.has_status = true;
> > +
> > +	success = true;
> > +out:
> > +	resp.type = CRIU_REQ_TYPE__WAIT_PID;
> > +	resp.success = success;
> > +
> > +	return send_criu_msg(sk, &resp);
> > +}
> > +
> >  static int handle_cpuinfo(int sk, CriuReq *msg)
> >  {
> >  	CriuResp resp = CRIU_RESP__INIT;
> > @@ -1031,7 +1072,13 @@ more:
> >  		ret = pre_dump_loop(sk, msg);
> >  		break;
> >  	case CRIU_REQ_TYPE__PAGE_SERVER:
> > -		ret =  start_page_server_req(sk, msg->opts);
> > +		ret = start_page_server_req(sk, msg->opts, true);
> > +		break;
> > +	case CRIU_REQ_TYPE__PAGE_SERVER_CHLD:
> > +		ret = start_page_server_req(sk, msg->opts, false);
> > +		break;
> > +	case CRIU_REQ_TYPE__WAIT_PID:
> > +		ret =  handle_wait_pid(sk, msg->pid);
> >  		break;
> >  	case CRIU_REQ_TYPE__CPUINFO_DUMP:
> >  	case CRIU_REQ_TYPE__CPUINFO_CHECK:
> > diff --git a/images/rpc.proto b/images/rpc.proto
> > index 48e42e2..71f47d5 100644
> > --- a/images/rpc.proto
> > +++ b/images/rpc.proto
> > @@ -142,6 +142,9 @@ enum criu_req_type {
> >  	FEATURE_CHECK	= 9;
> >  
> >  	VERSION		= 10;
> > +
> > +	WAIT_PID	= 11;
> > +	PAGE_SERVER_CHLD = 12;
> >  }
> >  
> >  /*
> > @@ -176,6 +179,9 @@ message criu_req {
> >  	 * via RPC.
> >  	 */
> >  	optional criu_features		features	= 5;
> > +
> > +	/* 'pid' is used for WAIT_PID */
> > +	optional uint32			pid		= 6;
> >  }
> >  
> >  /*
> > @@ -196,6 +202,8 @@ message criu_resp {
> >  	optional criu_features		features	= 8;
> >  	optional string			cr_errmsg	= 9;
> >  	optional criu_version		version		= 10;
> > +
> > +	optional int32			status		= 11;
> >  }
> >  
> >  /* Answer for criu_req_type.VERSION requests */
> > 
>