tests: Trim rtc path in testRtcHctosys()

We find readlink returns a string with the trailing newline char by
default, and the test can NOT handle the case.

Besides, it is adapted to extract rtc devname for both absolute and
relative symlinks. Corresponding string variable is converted to
lower camel case.

Flag: EXEMPT bug fix
Bug: 427712126
Merged-In: I028477e48fab999e09be2497326e1176f71f2200
Change-Id: I028477e48fab999e09be2497326e1176f71f2200
Signed-off-by: Evan Wei <evwei@nvidia.com>

api/sysfs/src/com/android/tests/sysfs/KernelApiSysfsTest.java

diff --git a/api/sysfs/src/com/android/tests/sysfs/KernelApiSysfsTest.java b/api/sysfs/src/com/android/tests/sysfs/KernelApiSysfsTest.java
index 247356e..50cf755 100644
--- a/api/sysfs/src/com/android/tests/sysfs/KernelApiSysfsTest.java
+++ b/api/sysfs/src/com/android/tests/sysfs/KernelApiSysfsTest.java
@@ -226,16 +226,22 @@
         String rtc = getKernelConfigUnquotedString("CONFIG_RTC_HCTOSYS_DEVICE");
         if (rtc == null)
             fail("Could not find CONFIG_RTC_HCTOSYS_DEVICE");
-        String rtc_link = getDevice().executeShellCommand("readlink /dev/rtc");
-        if (rtc_link.isEmpty()) {
+        String rtcPath = getDevice().executeShellCommand("readlink -n /dev/rtc");
+        if (rtcPath.isEmpty()) {
             if (getDevice().doesFileExist("/dev/rtc0")) {
-                rtc_link = "rtc0";
+                rtcPath = "rtc0";
             } else {
                 fail("Neither /dev/rtc nor /dev/rtc0 exist");
             }
         }
-        assertTrue(String.format("(%s) does not match RTC_HCTOSYS_DEVICE (%s)", rtc_link, rtc),
-                rtc.equals(rtc_link));
+
+        /*
+         * The readlink command can return a full path (e.g. /dev/rtc0) or just the device name
+         * (e.g. rtc0). In the first case, we need to extract the device name.
+         */
+        String rtcName = rtcPath.substring(rtcPath.lastIndexOf('/') + 1);
+        assertTrue(String.format("(%s) does not match RTC_HCTOSYS_DEVICE (%s)", rtcName, rtc),
+                rtc.equals(rtcName));
     }
 
     /* Check that locking and unlocking a wake lock works.. */