criu: add cmp_version()

src/lxc/criu.c

@@ -126,6 +126,47 @@ static int load_tty_major_minor(char *directory, char *output, int len)
 	return 0;
 }
 
+static int cmp_version(const char *v1, const char *v2)
+{
+	int ret;
+	int oct_v1[3], oct_v2[3];
+
+	memset(oct_v1, -1, sizeof(oct_v1));
+	memset(oct_v2, -1, sizeof(oct_v2));
+
+	ret = sscanf(v1, "%d.%d.%d", &oct_v1[0], &oct_v1[1], &oct_v1[2]);
+	if (ret < 1)
+		return -1;
+
+	ret = sscanf(v2, "%d.%d.%d", &oct_v2[0], &oct_v2[1], &oct_v2[2]);
+	if (ret < 1)
+		return -1;
+
+	/* Major version is greater. */
+	if (oct_v1[0] > oct_v2[0])
+		return 1;
+
+	if (oct_v1[0] < oct_v2[0])
+		return -1;
+
+	/* Minor number is greater.*/
+	if (oct_v1[1] > oct_v2[1])
+		return 1;
+
+	if (oct_v1[1] < oct_v2[1])
+		return -1;
+
+	/* Patch number is greater. */
+	if (oct_v1[2] > oct_v2[2])
+		return 1;
+
+	/* Patch numbers are equal. */
+	if (oct_v1[2] == oct_v2[2])
+		return 0;
+
+	return -1;
+}
+
 static void exec_criu(struct criu_opts *opts)
 {
 	char **argv, log[PATH_MAX];
@@ -500,7 +541,7 @@ static void exec_criu(struct criu_opts *opts)
 			struct lxc_netdev *n = it->elem;
 			bool external_not_veth;
 
-			if (strcmp(opts->criu_version, CRIU_EXTERNAL_NOT_VETH) >= 0) {
+			if (cmp_version(opts->criu_version, CRIU_EXTERNAL_NOT_VETH) >= 0) {
 				/* Since criu version 2.8 the usage of --veth-pair
 				 * has been deprecated:
 				 * git tag --contains f2037e6d3445fc400