[PATCH v5] selftests: rtc: Fixes rtctest error handling.

[Atul Kumar Pant <atulpant.linux@gmail.com>]

Adds a check to verify if the rtc device file is valid or not
and prints a useful error message if the file is not accessible.

Signed-off-by: Atul Kumar Pant <atulpant.linux@gmail.com>
---

changes since v4:
    Updated the commit message.

changes since v3:
    Added Linux-kselftest and Linux-kernel mailing lists.

changes since v2:
    Changed error message when rtc file does not exist.

changes since v1:
    Removed check for uid=0
    If rtc file is invalid, then exit the test.

 tools/testing/selftests/rtc/rtctest.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/rtc/rtctest.c b/tools/testing/selftests/rtc/rtctest.c
index 63ce02d1d5cc..630fef735c7e 100644
--- a/tools/testing/selftests/rtc/rtctest.c
+++ b/tools/testing/selftests/rtc/rtctest.c
@@ -17,6 +17,7 @@
 #include <unistd.h>
 
 #include "../kselftest_harness.h"
+#include "../kselftest.h"
 
 #define NUM_UIE 3
 #define ALARM_DELTA 3
@@ -419,6 +420,8 @@ __constructor_order_last(void)
 
 int main(int argc, char **argv)
 {
+	int ret = -1;
+
 	switch (argc) {
 	case 2:
 		rtc_file = argv[1];
@@ -430,5 +433,11 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
-	return test_harness_run(argc, argv);
+	// Run the test if rtc_file is valid
+	if (access(rtc_file, F_OK) == 0)
+		ret = test_harness_run(argc, argv);
+	else
+		ksft_exit_fail_msg("[ERROR]: Cannot access rtc file %s - Exiting\n", rtc_file);
+
+	return ret;
 }
-- 
2.25.1