zdtm: add loginuid restore test

Signed-off-by: Dmitry Safonov <dsafonov@odin.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm/live/static/Makefile

@@ -145,6 +145,7 @@ TST_NOFILE	=				\
 		bridge				\
 		vfork00				\
 		oom_score_adj			\
+		loginuid			\
 #		jobctl00			\
 
 TST_FILE	=				\

test/zdtm/live/static/loginuid.c

+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "zdtmtst.h"
+
+const char *test_doc = "Check for /proc/self/loginuid restore";
+const char *test_author = "Dmitry Safonov <dsafonov@odin.com>";
+
+const char loginuid_self[] = "/proc/self/loginuid";
+const uid_t test_value = 3;
+const uid_t INVALID_UID = (uid_t)-1;
+
+uid_t get_loginuid(const char *path, int *err)
+{
+	int fd;
+	ssize_t num;
+	char buf[11];
+
+	*err = 0;
+	fd = open(path, O_RDONLY);
+	if (fd < 0) {
+		pr_perror("Failed to open %s", path);
+		goto out;
+	}
+
+	num = read(fd, buf, 10);
+	close(fd);
+	if (num < 0) {
+		pr_perror("Unable to read %s", path);
+		goto out;
+	}
+	buf[num] = '\0';
+
+	return strtol(buf, NULL, 10);
+
+out:
+	*err = -1;
+	return 0;
+}
+
+int set_loginuid(const char *path, uid_t value)
+{
+	int fd, ret = 0;
+	char buf[11];
+
+	fd = open(path, O_RDWR);
+	if (fd < 0) {
+		pr_perror("Failed to open %s", path);
+		return -1;
+	}
+
+	snprintf(buf, 11, "%u", value);
+
+	if (write(fd, buf, 11) < 0) {
+		pr_perror("Write %s to %s failed", buf, path);
+		ret = -1;
+	}
+
+	close(fd);
+	return ret;
+}
+
+
+int main(int argc, char *argv[])
+{
+	int ret;
+	uid_t new_loginuid;
+
+	/* unset before test */
+	if (set_loginuid(loginuid_self, INVALID_UID) < 0)
+		return -1;
+
+	test_init(argc, argv);
+
+	if (set_loginuid(loginuid_self, test_value) < 0)
+		return -1;
+
+	test_daemon();
+	test_waitsig();
+
+	new_loginuid = get_loginuid(loginuid_self, &ret);
+	if (ret < 0)
+		return -1;
+
+	if (new_loginuid != test_value) {
+		fail("loginuid value %d is different after restore: %d\n",
+				test_value, new_loginuid);
+		return -1;
+	}
+
+	pass();
+	return 0;
+}