Revert "AlarmManagerService: remove legacy /dev/alarm support"

This reverts commit f68cdb9cb4841765d9d55d4a95259e9c3bb3ecc1.

Change-Id: I13e954656771f32c6156b4c4adb52922bcd0717a
diff --git a/services/core/jni/com_android_server_AlarmManagerService.cpp b/services/core/jni/com_android_server_AlarmManagerService.cpp
index 36105bd..407c072 100644
--- a/services/core/jni/com_android_server_AlarmManagerService.cpp
+++ b/services/core/jni/com_android_server_AlarmManagerService.cpp
@@ -37,28 +37,13 @@
 #include <errno.h>
 #include <unistd.h>
 #include <linux/ioctl.h>
+#include <linux/android_alarm.h>
 #include <linux/rtc.h>
 
-#include <array>
 #include <memory>
 
 namespace android {
 
-static constexpr int ANDROID_ALARM_TIME_CHANGE_MASK = 1 << 16;
-
-/**
- * The AlarmManager alarm constants:
- *
- *   RTC_WAKEUP
- *   RTC
- *   REALTIME_WAKEUP
- *   REALTIME
- *   SYSTEMTIME (only defined in old alarm driver header, possibly unused?)
- *
- * We also need an extra CLOCK_REALTIME fd which exists specifically to be
- * canceled on RTC changes.
- */
-static const size_t ANDROID_ALARM_TYPE_COUNT = 5;
 static const size_t N_ANDROID_TIMERFDS = ANDROID_ALARM_TYPE_COUNT + 1;
 static const clockid_t android_alarm_to_clockid[N_ANDROID_TIMERFDS] = {
     CLOCK_REALTIME_ALARM,
@@ -68,39 +53,98 @@
     CLOCK_MONOTONIC,
     CLOCK_REALTIME,
 };
-
-typedef std::array<int, N_ANDROID_TIMERFDS> TimerFds;
+/* to match the legacy alarm driver implementation, we need an extra
+   CLOCK_REALTIME fd which exists specifically to be canceled on RTC changes */
 
 class AlarmImpl
 {
 public:
-    AlarmImpl(const TimerFds &fds, int epollfd, int rtc_id) :
-        fds{fds}, epollfd{epollfd}, rtc_id{rtc_id} { }
-    ~AlarmImpl();
+    AlarmImpl(int *fds, size_t n_fds);
+    virtual ~AlarmImpl();
+
+    virtual int set(int type, struct timespec *ts) = 0;
+    virtual int setTime(struct timeval *tv) = 0;
+    virtual int waitForAlarm() = 0;
+
+protected:
+    int *fds;
+    size_t n_fds;
+};
+
+class AlarmImplAlarmDriver : public AlarmImpl
+{
+public:
+    explicit AlarmImplAlarmDriver(int fd) : AlarmImpl(&fd, 1) { }
+
+    int set(int type, struct timespec *ts);
+    int setTime(struct timeval *tv);
+    int waitForAlarm();
+};
+
+class AlarmImplTimerFd : public AlarmImpl
+{
+public:
+    AlarmImplTimerFd(int fds[N_ANDROID_TIMERFDS], int epollfd, int rtc_id) :
+        AlarmImpl(fds, N_ANDROID_TIMERFDS), epollfd(epollfd), rtc_id(rtc_id) { }
+    ~AlarmImplTimerFd();
 
     int set(int type, struct timespec *ts);
     int setTime(struct timeval *tv);
     int waitForAlarm();
 
 private:
-    const TimerFds fds;
-    const int epollfd;
-    const int rtc_id;
+    int epollfd;
+    int rtc_id;
 };
 
+AlarmImpl::AlarmImpl(int *fds_, size_t n_fds) : fds(new int[n_fds]),
+        n_fds(n_fds)
+{
+    memcpy(fds, fds_, n_fds * sizeof(fds[0]));
+}
+
 AlarmImpl::~AlarmImpl()
 {
-    for (auto fd : fds) {
-        epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, nullptr);
-        close(fd);
+    for (size_t i = 0; i < n_fds; i++) {
+        close(fds[i]);
     }
+    delete [] fds;
+}
 
+int AlarmImplAlarmDriver::set(int type, struct timespec *ts)
+{
+    return ioctl(fds[0], ANDROID_ALARM_SET(type), ts);
+}
+
+int AlarmImplAlarmDriver::setTime(struct timeval *tv)
+{
+    struct timespec ts;
+    int res;
+
+    ts.tv_sec = tv->tv_sec;
+    ts.tv_nsec = tv->tv_usec * 1000;
+    res = ioctl(fds[0], ANDROID_ALARM_SET_RTC, &ts);
+    if (res < 0)
+        ALOGV("ANDROID_ALARM_SET_RTC ioctl failed: %s\n", strerror(errno));
+    return res;
+}
+
+int AlarmImplAlarmDriver::waitForAlarm()
+{
+    return ioctl(fds[0], ANDROID_ALARM_WAIT);
+}
+
+AlarmImplTimerFd::~AlarmImplTimerFd()
+{
+    for (size_t i = 0; i < N_ANDROID_TIMERFDS; i++) {
+        epoll_ctl(epollfd, EPOLL_CTL_DEL, fds[i], NULL);
+    }
     close(epollfd);
 }
 
-int AlarmImpl::set(int type, struct timespec *ts)
+int AlarmImplTimerFd::set(int type, struct timespec *ts)
 {
-    if (static_cast<size_t>(type) > ANDROID_ALARM_TYPE_COUNT) {
+    if (type > ANDROID_ALARM_TYPE_COUNT) {
         errno = EINVAL;
         return -1;
     }
@@ -118,7 +162,7 @@
     return timerfd_settime(fds[type], TFD_TIMER_ABSTIME, &spec, NULL);
 }
 
-int AlarmImpl::setTime(struct timeval *tv)
+int AlarmImplTimerFd::setTime(struct timeval *tv)
 {
     struct rtc_time rtc;
     struct tm tm, *gmtime_res;
@@ -169,7 +213,7 @@
     return res;
 }
 
-int AlarmImpl::waitForAlarm()
+int AlarmImplTimerFd::waitForAlarm()
 {
     epoll_event events[N_ANDROID_TIMERFDS];
 
@@ -239,12 +283,25 @@
     return 0;
 }
 
+static jlong init_alarm_driver()
+{
+    int fd = open("/dev/alarm", O_RDWR);
+    if (fd < 0) {
+        ALOGV("opening alarm driver failed: %s", strerror(errno));
+        return 0;
+    }
+
+    AlarmImpl *ret = new AlarmImplAlarmDriver(fd);
+    return reinterpret_cast<jlong>(ret);
+}
+
 static const char rtc_sysfs[] = "/sys/class/rtc";
 
 static bool rtc_is_hctosys(unsigned int rtc_id)
 {
     android::String8 hctosys_path = String8::format("%s/rtc%u/hctosys",
             rtc_sysfs, rtc_id);
+
     FILE *file = fopen(hctosys_path.string(), "re");
     if (!file) {
         ALOGE("failed to open %s: %s", hctosys_path.string(), strerror(errno));
@@ -298,22 +355,22 @@
     return -1;
 }
 
-static jlong android_server_AlarmManagerService_init(JNIEnv*, jobject)
+static jlong init_timerfd()
 {
     int epollfd;
-    TimerFds fds;
+    int fds[N_ANDROID_TIMERFDS];
 
-    epollfd = epoll_create(fds.size());
+    epollfd = epoll_create(N_ANDROID_TIMERFDS);
     if (epollfd < 0) {
-        ALOGE("epoll_create(%zu) failed: %s", fds.size(),
+        ALOGV("epoll_create(%zu) failed: %s", N_ANDROID_TIMERFDS,
                 strerror(errno));
         return 0;
     }
 
-    for (size_t i = 0; i < fds.size(); i++) {
+    for (size_t i = 0; i < N_ANDROID_TIMERFDS; i++) {
         fds[i] = timerfd_create(android_alarm_to_clockid[i], 0);
         if (fds[i] < 0) {
-            ALOGE("timerfd_create(%u) failed: %s",  android_alarm_to_clockid[i],
+            ALOGV("timerfd_create(%u) failed: %s",  android_alarm_to_clockid[i],
                     strerror(errno));
             close(epollfd);
             for (size_t j = 0; j < i; j++) {
@@ -323,16 +380,16 @@
         }
     }
 
-    AlarmImpl *ret = new AlarmImpl(fds, epollfd, wall_clock_rtc());
+    AlarmImpl *ret = new AlarmImplTimerFd(fds, epollfd, wall_clock_rtc());
 
-    for (size_t i = 0; i < fds.size(); i++) {
+    for (size_t i = 0; i < N_ANDROID_TIMERFDS; i++) {
         epoll_event event;
         event.events = EPOLLIN | EPOLLWAKEUP;
         event.data.u32 = i;
 
         int err = epoll_ctl(epollfd, EPOLL_CTL_ADD, fds[i], &event);
         if (err < 0) {
-            ALOGE("epoll_ctl(EPOLL_CTL_ADD) failed: %s", strerror(errno));
+            ALOGV("epoll_ctl(EPOLL_CTL_ADD) failed: %s", strerror(errno));
             delete ret;
             return 0;
         }
@@ -346,7 +403,7 @@
     int err = timerfd_settime(fds[ANDROID_ALARM_TYPE_COUNT],
             TFD_TIMER_ABSTIME | TFD_TIMER_CANCEL_ON_SET, &spec, NULL);
     if (err < 0) {
-        ALOGE("timerfd_settime() failed: %s", strerror(errno));
+        ALOGV("timerfd_settime() failed: %s", strerror(errno));
         delete ret;
         return 0;
     }
@@ -354,6 +411,16 @@
     return reinterpret_cast<jlong>(ret);
 }
 
+static jlong android_server_AlarmManagerService_init(JNIEnv*, jobject)
+{
+    jlong ret = init_alarm_driver();
+    if (ret) {
+        return ret;
+    }
+
+    return init_timerfd();
+}
+
 static void android_server_AlarmManagerService_close(JNIEnv*, jobject, jlong nativeData)
 {
     AlarmImpl *impl = reinterpret_cast<AlarmImpl *>(nativeData);