zdtm: Construct all root dirs and files in launcher

Instead of doing some dirs/files/links in launcher and some in
libzdtm, make everything in the launcher. The library is then
just to set up the namespaces.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.py

@@ -141,6 +141,32 @@ class ns_flavor:
 		for lib in libs:
 			self.__copy_one(lib)
 
+	def __mknod(self, name, rdev = None):
+		name = "/dev/" + name
+		if not rdev:
+			if not os.access(name, os.F_OK):
+				print "Skipping %s at root" % name
+				return
+			else:
+				rdev = os.stat(name).st_rdev
+
+		name = self.root + name
+		os.mknod(name, stat.S_IFCHR, rdev)
+		os.chmod(name, 0666)
+
+	def __construct_root(self):
+		for dir in ["/bin", "/sbin", "/etc", "/lib", "/lib64", "/dev", "/dev/pts", "/tmp", "/usr", "/proc"]:
+			os.mkdir(self.root + dir)
+			os.chmod(self.root + dir, 0777)
+
+		for ldir in [ "/bin", "/sbin", "/lib", "/lib64" ]:
+			os.symlink(".." + ldir, self.root + "/usr" + ldir)
+
+		self.__mknod("tty", os.makedev(5, 0))
+		self.__mknod("null", os.makedev(1, 3))
+		self.__mknod("net/tun")
+		self.__mknod("rtc")
+
 	def init(self, test_bin, deps):
 		subprocess.check_call(["mount", "--make-private", "--bind", ".", self.root])
 		self.root_mounted = True
@@ -150,14 +176,7 @@ class ns_flavor:
 				fcntl.flock(o, fcntl.LOCK_EX)
 				if not os.access(self.root + "/.constructed", os.F_OK):
 					print "Construct root for %s" % test_bin
-					for dir in ["/bin", "/sbin", "/etc", "/lib", "/lib64", "/dev", "/tmp", "/usr"]:
-						os.mkdir(self.root + dir)
-						os.chmod(self.root + dir, 0777)
-
-					os.mknod(self.root + "/dev/tty", stat.S_IFCHR, os.makedev(5, 0))
-					os.chmod(self.root + "/dev/tty", 0666)
-					for ldir in [ "/bin", "/sbin", "/lib", "/lib64" ]:
-						os.symlink(".." + ldir, self.root + "/usr" + ldir)
+					self.__construct_root()
 					os.mknod(self.root + "/.constructed", stat.S_IFREG | 0600)
 
 		self.__copy_libs(test_bin)

test/zdtm.sh

@@ -541,7 +541,18 @@ construct_root()
 	done
 
 	mkdir $root/dev
+	mkdir $root/dev/pts
 	mknod -m 0666 $root/dev/tty c 5 0
+	mknod -m 0666 $root/dev/null c 1 3
+	if [ -r "/dev/net/tun" ]; then
+		mkdir $root/dev/net/
+		mknod -m 0666 $root/dev/net/tun $(stat -c "0x%t" /dev/net/tun) $(stat -c "0x%T" /dev/net/tun)
+	fi
+	if [ -r "/dev/rtc" ]; then
+		mknod -m 0666 $root/dev/rtc $(stat -c "0x%t" /dev/rtc) $(stat -c "0x%T" /dev/rtc)
+	fi
+
+	mkdir $root/proc
 
 	# make 'tmp' dir under new root
 	mkdir -p $tmpdir

test/zdtm/lib/ns.c

@@ -77,11 +77,6 @@ static int prepare_mntns()
 			return -1;
 		}
 
-		if (mkdir("proc", 0777) && errno != EEXIST) {
-			fprintf(stderr, "mkdir(proc) failed: %m\n");
-			return -1;
-		}
-
 		/*
 		 * proc and sysfs can be mounted in an unprivileged namespace,
 		 * if they are already mounted when the user namespace is created.
@@ -97,14 +92,6 @@ static int prepare_mntns()
 			return -1;
 		}
 
-		if (mkdir("/dev", 0755) && errno != EEXIST) {
-			fprintf(stderr, "mkdir(/dev) failed: %m\n");
-			return -1;
-		}
-		if (mkdir("/dev/pts", 0755) && errno != EEXIST) {
-			fprintf(stderr, "mkdir(/dev/pts) failed: %m\n");
-			return -1;
-		}
 		if (mount("pts", "/dev/pts", "devpts", MS_MGC_VAL, "mode=666,ptmxmode=666,newinstance")) {
 			fprintf(stderr, "mount(/dev/pts) failed: %m\n");
 			return -1;
@@ -127,14 +114,7 @@ static int prepare_mntns()
 				return -1;
 			}
 		}
-		if (access("/dev/tty", F_OK)) {
-			if (mknod("/dev/tty", 0666 | S_IFCHR, makedev(5, 0)) == 0) {
-				chmod("/dev/tty", 0666);
-			} else if (errno != EEXIST) {
-				fprintf(stderr, "mknod(/dev/tty) failed: %m\n");
-				return -1;
-			}
-		}
+
 		if (fchdir(dfd)) {
 			fprintf(stderr, "fchdir() failed: %m\n");
 			return -1;
@@ -340,56 +320,6 @@ int ns_init(int argc, char **argv)
 	exit(1);
 }
 
-static int construct_root()
-{
-	struct stat st;
-	char *root;
-	int dfd;
-
-	root = getenv("ZDTM_ROOT");
-	if (!root) {
-		fprintf(stderr, "ZDTM_ROOT isn't set\n");
-		return -1;
-	}
-
-	dfd = open(".", O_RDONLY);
-	if (dfd == -1) {
-		fprintf(stderr, "open(.) failed: %m\n");
-		return -1;
-	}
-	if (chdir(root)) {
-		fprintf(stderr, "chdir(%s): %m\n", root);
-		return -1;
-	}
-
-	mkdir("dev", 0777);
-	chmod("dev", 0777);
-	mknod("dev/null", 0777 | S_IFCHR, makedev(1, 3));
-	chmod("dev/null", 0777);
-	if (stat("/dev/net/tun", &st))
-		fprintf(stderr, "Unable to stat /dev/net/tun: %m");
-	else {
-		mkdir("dev/net", 0777);
-		mknod("dev/net/tun", 0777 | S_IFCHR, st.st_rdev);
-		chmod("dev/net/tun", 0777);
-	}
-
-	if (stat("/dev/rtc", &st)) {
-		fprintf(stderr, "Unable to stat /dev/rtc: %m");
-		return -1;
-	}
-	mknod("dev/rtc", 0777 | S_IFCHR, st.st_rdev);
-	chmod("dev/rtc", 0777);
-
-	if (fchdir(dfd)) {
-		fprintf(stderr, "fchdir() failed: %m\n");
-		return -1;
-	}
-	close(dfd);
-
-	return 0;
-}
-
 #define UID_MAP "0 100000 100000\n100000 200000 50000"
 #define GID_MAP "0 400000 50000\n50000 500000 100000"
 void ns_create(int argc, char **argv)
@@ -417,9 +347,6 @@ void ns_create(int argc, char **argv)
 	if (val)
 		flags |= CLONE_NEWUSER;
 
-	if (construct_root())
-		exit(1);
-
 	pid = clone(ns_exec, args.stack_ptr, flags, &args);
 	if (pid < 0) {
 		fprintf(stderr, "clone() failed: %m\n");