[LTP] [PATCH v3 1/2] lib: tst_rtctime: close RTC fd on the ioctl() error path

[Kuba Pawlak]

tst_rtc_ioctl() opens the RTC device with SAFE_OPEN() but returns -1 on
an ioctl() failure without closing the descriptor, leaking it on every
failed call. The RTC character device is exclusive-open, so a leaked fd
makes the next tst_rtc_ioctl() open fail with EBUSY.

This was mostly latent because the failure path was rarely taken, but it
is now hit routinely on RTCs that reject RTC_SET_TIME (e.g. Qualcomm PMIC
RTCs returning -ENODEV). Close the fd on the error path and preserve
errno so callers can still inspect the ioctl() failure reason.

Signed-off-by: Kuba Pawlak <kuba.pawlak@canonical.com>
---
v3: drop the errno save/restore around SAFE_CLOSE(); a successful close()
    does not clobber errno, and SAFE_CLOSE() breaks the test on failure.

 lib/tst_rtctime.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/tst_rtctime.c b/lib/tst_rtctime.c
index c62ac73..99c16ec 100644
--- a/lib/tst_rtctime.c
+++ b/lib/tst_rtctime.c
@@ -117,11 +117,12 @@ int tst_rtc_ioctl(const char *rtc_dev, unsigned long request,
 
 	ret = ioctl(rtc_fd, request, rtc_tm);
 
-	if (ret != 0)
+	if (ret != 0) {
+		SAFE_CLOSE(rtc_fd);
 		return -1;
+	}
 
-	if (rtc_fd > 0)
-		SAFE_CLOSE(rtc_fd);
+	SAFE_CLOSE(rtc_fd);
 
 	return 0;
 }
-- 
2.43.0