zdtm: Introduce explicit prepare_namespaces() routine

This one is to set up uids for userns, do ip l s lo up for netns
and do the prepare_mntns(). BTW, the latter's code is shifted one
tab left as this is where it should be.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm/lib/ns.c

@@ -19,7 +19,7 @@
 #include "ns.h"
 
 extern int pivot_root(const char *new_root, const char *put_old);
-static int prepare_mntns()
+static int prepare_mntns(void)
 {
 	int dfd, ret;
 	char *root;
@@ -124,6 +124,21 @@ static int prepare_mntns()
 	return 0;
 }
 
+static int prepare_namespaces(void)
+{
+	if (setuid(0) || setgid(0) || setgroups(0, NULL)) {
+		fprintf(stderr, "set*id failed: %m\n");
+		return -1;
+	}
+
+	system("ip link set up dev lo");
+
+	if (prepare_mntns())
+		return -1;
+
+	return 0;
+}
+
 #define NS_STACK_SIZE	4096
 
 /* All arguments should be above stack, because it grows down */
@@ -193,14 +208,8 @@ static int ns_exec(void *_arg)
 	close(args->status_pipe[1]);
 	read(STATUS_FD, buf, sizeof(buf));
 	shutdown(STATUS_FD, SHUT_RD);
-	if (setuid(0) || setgid(0) || setgroups(0, NULL)) {
-		fprintf(stderr, "set*id failed: %m\n");
-		return -1;
-	}
 
-	system("ip link set up dev lo");
-
-	if (prepare_mntns())
+	if (prepare_namespaces())
 		return -1;
 
 	setenv("ZDTM_NEWNS", "2", 1);