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

[Adrian Reber]

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