[CRIU] [PATCH 1/2] RPC: add version check interface

[Andrei Vagin]

On Wed, Mar 15, 2017 at 03:26:17PM +0100, Adrian Reber wrote:
> From: Adrian Reber <areber at redhat.com>
> 
> Instead of parsing the output of 'criu -V' this offers a RPC interface
> to get CRIU's version. In a follow up patch a test script is included
> to use the new interface:
> 
>  ./version.py
>  Connecting to CRIU in swrk mode to check the version:
>  RPC: Success
>  CRIU major 2
>  CRIU minor 12
>  CRIU gitid v2.12-635-g6d3ae4d
> 
> This change exports the following version fields:
>  * major
>  * minor
>  * gitid
>  * sublevel (optional)
>  * extra (optional)
>  * name (optional)
> 
> A 'gitid' of '0' (the '0' is a string) means that it is not built from a
> git checkout.
> 
> Signed-off-by: Adrian Reber <areber at redhat.com>
> ---
>  criu/cr-service.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  images/rpc.proto  | 14 +++++++++++
>  2 files changed, 83 insertions(+)
> 
> diff --git a/criu/cr-service.c b/criu/cr-service.c
> index 78142b0..7e17199 100644
> --- a/criu/cr-service.c
> +++ b/criu/cr-service.c
> @@ -15,6 +15,7 @@
>  #include <arpa/inet.h>
>  #include <sched.h>
>  
> +#include "version.h"
>  #include "crtools.h"
>  #include "cr_options.h"
>  #include "external.h"
> @@ -806,11 +807,76 @@ static int chk_keepopen_req(CriuReq *msg)
>  		return 0;
>  	else if (msg->type == CRIU_REQ_TYPE__FEATURE_CHECK)
>  		return 0;
> +	else if (msg->type == CRIU_REQ_TYPE__VERSION)
> +		return 0;
>  
>  	return -1;
>  }
>  
>  /*
> + * Return the version information, depending on the information
> + * available in version.h
> + */
> +static int handle_version(int sk, CriuReq * msg)
> +{
> +	CriuResp resp = CRIU_RESP__INIT;
> +	CriuVersion version = CRIU_VERSION__INIT;
> +	int pid, status;
> +	int ret;
> +
> +
> +	pid = fork();

Why do we need a new process here?

> +	if (pid < 0) {
> +		pr_perror("Can't fork");
> +		goto out;
> +	}
> +
> +	if (pid == 0) {
> +		/* This assumes we will always have a major and minor version */
> +		version.major = CRIU_VERSION_MAJOR;
> +		version.minor = CRIU_VERSION_MINOR;
> +		version.gitid = xstrdup(CRIU_GITID);
> +#ifdef CRIU_VERSION_SUBLEVEL
> +		version.has_sublevel = 1;
> +		version.sublevel = CRIU_VERSION_SUBLEVEL;
> +#endif
> +#ifdef CRIU_VERSION_EXTRA
> +		version.has_extra = 1;
> +		version.extra = CRIU_VERSION_EXTRA;
> +#endif
> +#ifdef CRIU_VERSION_NAME
> +		/* This is not actually exported in version.h */
> +		version.name = xstrdup(CRIU_VERSION_NAME);
> +#endif
> +		resp.type = msg->type;
> +		resp.success = true;
> +		resp.version = &version;
> +		return send_criu_msg(sk, &resp);
> +	}
> +
> +	ret = waitpid(pid, &status,  0);
> +	if (ret == -1)
> +		goto out;
> +
> +	if (WIFEXITED(status) && !WEXITSTATUS(status))
> +		/*
> +		 * The child process exited and was able to send the answer.
> +		 * Nothing more to do here.
> +		 */
> +		return 0;
> +
> +	/*
> +	 * The child process was not able to send an answer. Tell
> +	 * the RPC client that something did not work as expected.
> +	 */
> +out:
> +	resp.type = msg->type;
> +	resp.success = false;
> +
> +	return send_criu_msg(sk, &resp);
> +}
> +
> +/*
>   * Generic function to handle CRIU_REQ_TYPE__FEATURE_CHECK.
>   *
>   * The function will have resp.success = true for most cases
> @@ -1004,6 +1070,9 @@ more:
>  	case CRIU_REQ_TYPE__FEATURE_CHECK:
>  		ret = handle_feature_check(sk, msg);
>  		break;
> +	case CRIU_REQ_TYPE__VERSION:
> +		ret = handle_version(sk, msg);
> +		break;
>  
>  	default:
>  		send_criu_err(sk, "Invalid req");
> diff --git a/images/rpc.proto b/images/rpc.proto
> index f894ae1..bfb8dfc 100644
> --- a/images/rpc.proto
> +++ b/images/rpc.proto
> @@ -140,6 +140,8 @@ enum criu_req_type {
>  	CPUINFO_CHECK	= 8;
>  
>  	FEATURE_CHECK	= 9;
> +
> +	VERSION		= 10;
>  }
>  
>  /*
> @@ -193,4 +195,16 @@ message criu_resp {
>  	optional int32			cr_errno	= 7;
>  	optional criu_features		features	= 8;
>  	optional string			cr_errmsg	= 9;
> +	optional criu_version		version		= 10;
> +}
> +
> +/* Answer for criu_req_type.VERSION requests */
> +message criu_version {
> +	required int32			major		= 1;
> +	required int32			minor		= 2;
> +	/* if gitid is '0' then it is not from a git checkout */
> +	required string			gitid		= 3;

Maybe it should be optional? ^^^^^

> +	optional int32			sublevel	= 4;
> +	optional int32			extra		= 5;
> +	optional string			name		= 6;
>  }
> -- 
> 2.9.3
> 
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