zdtm: Sanitize cgroup00 test

Prepare it for multiple tasks by moving cg creation and
checking code into helpers.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm/live/static/cgroup00.c

@@ -12,13 +12,73 @@ const char *test_author	= "Pavel Emelianov <xemul@parallels.com>";
 char *dirname;
 TEST_OPTION(dirname, string, "cgroup directory name", 1);
 static const char *cgname = "zdtmtst";
-static const char *subname = "subcg";
+#define SUBNAME	"subcg"
+
+static int cg_move(char *name)
+{
+	int cgfd, l;
+	char paux[256];
+
+	sprintf(paux, "%s/%s", dirname, name);
+	mkdir(paux, 0600);
+
+	sprintf(paux, "%s/%s/tasks", dirname, name);
+
+	cgfd = open(paux, O_WRONLY);
+	if (cgfd < 0) {
+		err("Can't open tasks");
+		return -1;
+	}
+
+	l = write(cgfd, "0", 2);
+	close(cgfd);
+
+	if (l < 0) {
+		err("Can't move self to subcg");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int cg_check(char *name)
+{
+	int found = 0;
+	FILE *cgf;
+	char paux[256], aux[128];
+
+	cgf = fopen("/proc/self/cgroup", "r");
+	if (cgf == NULL)
+		return -1;
+
+	sprintf(aux, "name=%s:/%s\n", cgname, name);
+	while (fgets(paux, sizeof(paux), cgf)) {
+		char *s;
+
+		s = strchr(paux, ':') + 1;
+		test_msg("CMP [%s] vs [%s]\n", s, aux);
+		if (!strcmp(s, aux)) {
+			found = 1;
+			break;
+		}
+	}
+
+	fclose(cgf);
+
+	return found ? 0 : -1;
+}
+
+static void cg_cleanup(void)
+{
+	char paux[256];
+
+	sprintf(paux, "%s/%s", dirname, SUBNAME);
+	rmdir(paux);
+}
 
 int main(int argc, char **argv)
 {
-	int cgfd, l, ret = 1;
+	char aux[64];
-	char aux[32], paux[1024];
-	FILE *cgf;
 
 	test_init(argc, argv);
 
@@ -33,62 +93,24 @@ int main(int argc, char **argv)
 		goto out_rd;
 	}
 
-	sprintf(paux, "%s/%s", dirname, subname);
+	if (cg_move(SUBNAME))
-	mkdir(paux, 0600);
-
-	l = sprintf(aux, "%d", getpid());
-	sprintf(paux, "%s/%s/tasks", dirname, subname);
-
-	cgfd = open(paux, O_WRONLY);
-	if (cgfd < 0) {
-		err("Can't open tasks");
 		goto out_rs;
-	}
-
-	l = write(cgfd, aux, l);
-	close(cgfd);
-
-	if (l < 0) {
-		err("Can't move self to subcg");
-		goto out_rs;
-	}
-
-	close(cgfd);
 
 	test_daemon();
 	test_waitsig();
 
-	cgf = fopen("/proc/self/cgroup", "r");
+	if (cg_check(SUBNAME)) {
-	if (cgf == NULL) {
+		fail("Top level task cg changed");
-		fail("No cgroups file");
 		goto out_rs;
 	}
 
-	sprintf(aux, "name=%s:/%s\n", cgname, subname);
-	while (fgets(paux, sizeof(paux), cgf)) {
-		char *s;
-
-		s = strchr(paux, ':') + 1;
-		test_msg("CMP [%s] vs [%s]\n", s, aux);
-		if (!strcmp(s, aux)) {
-			ret = 0;
-			break;
-		}
-	}
-
-	fclose(cgf);
-
-	if (!ret)
 	pass();
-	else
-		fail("Task is not in subgroups");
 
 out_rs:
-	sprintf(paux, "%s/%s", dirname, subname);
+	cg_cleanup();
-	rmdir(paux);
 	umount(dirname);
 out_rd:
 	rmdir(dirname);
 out:
-	return ret;
+	return 0;
 }