Move time setting code from SystemClock to AlarmManagerService
On devices using /dev/rtc instead of /dev/alarm, updating the
time-of-day clock and RTC are separate syscalls. Hence the clock and
RTC could be left in inconsistent states if two threads called
SystemClock.setCurrentTimeMillis() simultaneously.
By moving this code into AlarmManagerService, we can put a global lock
around AlarmManagerService.setTime() and prevent the race condition.
Note that access to SystemClock.setCurrentTimeMillis() is now gated by
android.permission.SET_TIME, where before it was gated by filesystem
permissions (i.e., could the process write to /dev/alarm or /dev/rtc).
Change-Id: Ia34899a4cde983656305fd2ef466dfe908ed23c8
Signed-off-by: Greg Hackmann <ghackmann@google.com>
diff --git a/services/java/com/android/server/AlarmManagerService.java b/services/java/com/android/server/AlarmManagerService.java
index 2e1b0af..defc6ef 100644
--- a/services/java/com/android/server/AlarmManagerService.java
+++ b/services/java/com/android/server/AlarmManagerService.java
@@ -669,12 +669,19 @@
}
}
- public void setTime(long millis) {
+ public boolean setTime(long millis) {
mContext.enforceCallingOrSelfPermission(
"android.permission.SET_TIME",
"setTime");
- SystemClock.setCurrentTimeMillis(millis);
+ if (mNativeData == 0) {
+ Slog.w(TAG, "Not setting time since no alarm driver is available.");
+ return false;
+ }
+
+ synchronized (mLock) {
+ return setKernelTime(mNativeData, millis) == 0;
+ }
}
public void setTimeZone(String tz) {
@@ -1018,6 +1025,7 @@
private native void close(long nativeData);
private native void set(long nativeData, int type, long seconds, long nanoseconds);
private native int waitForAlarm(long nativeData);
+ private native int setKernelTime(long nativeData, long millis);
private native int setKernelTimezone(long nativeData, int minuteswest);
private void triggerAlarmsLocked(ArrayList<Alarm> triggerList, long nowELAPSED, long nowRTC) {