RPC: add version check interface

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 (optional)
 * sublevel (optional)
 * extra (optional)
 * name (optional)

The optional gitid field is not set when CRIU is not built from git.
Signed-off-by: Adrian Reber <areber@redhat.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

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"
@@ -799,10 +800,45 @@ 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;
+
+	/* This assumes we will always have a major and minor version */
+	version.major = CRIU_VERSION_MAJOR;
+	version.minor = CRIU_VERSION_MINOR;
+	if (strcmp(CRIU_GITID, "0")) {
+		version.gitid = 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 = CRIU_VERSION_NAME;
+#endif
+	resp.type = msg->type;
+	resp.success = true;
+	resp.version = &version;
+	return send_criu_msg(sk, &resp);
+}
+
 /*
  * Generic function to handle CRIU_REQ_TYPE__FEATURE_CHECK.
  *
@@ -969,6 +1005,9 @@ 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");

images/rpc.proto

@@ -139,6 +139,8 @@ enum criu_req_type {
 	CPUINFO_CHECK	= 8;
 
 	FEATURE_CHECK	= 9;
+
+	VERSION		= 10;
 }
 
 /*
@@ -191,4 +193,15 @@ 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;
+	optional string			gitid		= 3;
+	optional int32			sublevel	= 4;
+	optional int32			extra		= 5;
+	optional string			name		= 6;
 }