rtctest implements its own main() function with a rigid switch (argc)
check that only accepts an optional single argument for the RTC device
node path. This prevents kselftest_harness standard arguments from
working properly:

1. Passing filter options like -t <name> or -T <name> triggers a usage
   error because argc is greater than 2.
2. Passing -l or -h causes rtctest to treat "-l" or "-h" as the device
   node path and fail with access() errors before ever reaching the
   harness argument checker.

Parse command line arguments with getopt() to pass all kselftest harness
options (such as -t, -T, -v, -V, -f, -F, -r, -d, -h, and -l) through to
test_harness_run(), while preserving the ability to specify an optional
RTC device node path as a non-option argument. Also ensure optind is
reset before invoking test_harness_run() so the harness can inspect the
options, and bypass device accessibility checks when help or test
listing is requested.

Signed-off-by: Wake Liu <wakel@google.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
v2:
- Rebased onto v7.4-rc1, no code changes.
- Added Alexandre's Acked-by.

Alexandre, the other rtctest changes for v7.4 went through the RTC
tree. Would you be willing to queue this one there as well? Shuah,
please let me know if you would rather take it via kselftest.

v1: https://lore.kernel.org/all/20260910034821.2935214-1-wakel@google.com/

 tools/testing/selftests/rtc/rtctest.c | 44 +++++++++++++++++++++------
 1 file changed, 35 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/rtc/rtctest.c b/tools/testing/selftests/rtc/rtctest.c
index 552191fe1ca0..eb26d957835d 100644
--- a/tools/testing/selftests/rtc/rtctest.c
+++ b/tools/testing/selftests/rtc/rtctest.c
@@ -487,18 +487,44 @@ TEST_F_TIMEOUT(rtc, alarm_wkalm_set_minute, 65) {
 int main(int argc, char **argv)
 {
 	int ret = -1;
+	int opt, i;
+	int non_opt = 0;
+
+	while ((opt = getopt(argc, argv, "dhlF:f:V:v:t:T:r:")) != -1) {
+		switch (opt) {
+		case 'h':
+			fprintf(stderr,
+				"Usage: %s [-h|-l|-d] [-t|-T|-v|-V|-f|-F|-r name] [rtcdev]\n\n",
+				argv[0]);
+			optind = 1;
+			return test_harness_run(argc, argv);
+		case 'l':
+			optind = 1;
+			return test_harness_run(argc, argv);
+		case '?':
+			fprintf(stderr,
+				"Usage: %s [-h|-l|-d] [-t|-T|-v|-V|-f|-F|-r name] [rtcdev]\n",
+				argv[0]);
+			return KSFT_FAIL;
+		default:
+			break;
+		}
+	}
 
-	switch (argc) {
-	case 2:
-		rtc_file = argv[1];
-		/* FALLTHROUGH */
-	case 1:
-		break;
-	default:
-		fprintf(stderr, "usage: %s [rtcdev]\n", argv[0]);
-		return 1;
+	for (i = optind; i < argc; i++) {
+		if (non_opt == 0) {
+			rtc_file = argv[i];
+			non_opt++;
+		} else {
+			fprintf(stderr,
+				"Usage: %s [-h|-l|-d] [-t|-T|-v|-V|-f|-F|-r name] [rtcdev]\n",
+				argv[0]);
+			return KSFT_FAIL;
+		}
 	}
 
+	optind = 1;
+
 	/* Run the test if rtc_file is accessible */
 	if (access(rtc_file, R_OK) == 0)
 		ret = test_harness_run(argc, argv);

base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
-- 
2.56.0.398.g882cbad275-goog