lib/c: add criu_get_version()

Although the CRIU version is exported in macros in version.h it only
contains the CRIU version of libcriu during build time.

As it is possible that CRIU is upgraded since the last time something
was built against libcriu, this adds functions to query the actual CRIU
binary about its version.

Signed-off-by: Adrian Reber <areber@redhat.com>

2 files changed, 97 insertions, 0 deletions

diff --git a/lib/c/criu.c b/lib/c/criu.c
index de57a65dc..d052f8d1f 100644
--- a/lib/c/criu.c
+++ b/lib/c/criu.c
@@ -1668,3 +1668,68 @@ int criu_restore_child(void)
 {
 	return criu_local_restore_child(global_opts);
 }
+
+int criu_local_get_version(criu_opts *opts)
+{
+	int ret = -1;
+	CriuReq req	= CRIU_REQ__INIT;
+	CriuResp *resp	= NULL;
+
+	saved_errno = 0;
+
+	req.type	= CRIU_REQ_TYPE__VERSION;
+	req.opts	= opts->rpc;
+
+	ret = send_req_and_recv_resp(opts, &req, &resp);
+	if (ret)
+		goto exit;
+
+	if (resp->success) {
+		ret = resp->version->major_number * 10000;
+		ret += resp->version->minor_number * 100;
+		if (resp->version->has_sublevel)
+			ret += resp->version->sublevel;
+		if (resp->version->gitid) {
+			/* Taken from runc: a git release -> minor + 1 */
+			ret -= (ret % 100);
+			ret += 100;
+		}
+	} else {
+		ret = -EBADE;
+	}
+
+exit:
+	if (resp)
+		criu_resp__free_unpacked(resp, NULL);
+
+	swrk_wait(opts);
+
+	errno = saved_errno;
+
+	return ret;
+}
+
+int criu_get_version(void)
+{
+	return criu_local_get_version(global_opts);
+}
+
+int criu_local_check_version(criu_opts *opts, int minimum)
+{
+	int version;
+
+	version = criu_local_get_version(opts);
+
+	if (version < 0)
+		return version;
+
+	if (minimum <= version)
+		return 1;
+
+	return 0;
+}
+
+int criu_check_version(int minimum)
+{
+	return criu_local_check_version(global_opts, minimum);
+}
diff --git a/lib/c/criu.h b/lib/c/criu.h
index 3a9204f5b..49f7a7005 100644
--- a/lib/c/criu.h
+++ b/lib/c/criu.h
@@ -159,6 +159,35 @@ typedef void *criu_predump_info;
 int criu_dump_iters(int (*more)(criu_predump_info pi));
 
 /*
+ * Get the version of the actual binary used for RPC.
+ *
+ * As this library is just forwarding all tasks to an
+ * independent (of this library) CRIU binary, the actual
+ * version of the CRIU binary can be different then the
+ * hardcoded values in the libary (version.h).
+ * To be able to easily check the version of the CRIU binary
+ * the function criu_get_version() returns the version
+ * in the following format:
+ *
+ * (major * 10000) + (minor * 100) + sublevel
+ *
+ * If the CRIU binary has been built from a git checkout
+ * minor will increased by one.
+ */
+int criu_get_version(void);
+
+/*
+ * Check if the version of the CRIU binary is at least
+ * 'minimum'. Version has to be in the same format as
+ * described for criu_get_version().
+ *
+ * Returns 1 if CRIU is at least 'minimum'.
+ * Returns 0 if CRIU is too old.
+ * Returns < 0 if there was an error.
+ */
+int criu_check_version(int minimum);
+
+/*
  * Same as the list above, but lets you have your very own options
  * structure and lets you set individual options in it.
  */
@@ -229,6 +258,9 @@ int criu_local_restore(criu_opts *opts);
 int criu_local_restore_child(criu_opts *opts);
 int criu_local_dump_iters(criu_opts *opts, int (*more)(criu_predump_info pi));
 
+int criu_local_get_version(criu_opts *opts);
+int criu_local_check_version(criu_opts *opts, int minimum);
+
 #ifdef __GNUG__
 }
 #endif