1 /*
2 * Copyright (C) 2022 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #define LOG_TAG "SystemClockTime"
18
19 #include <android-base/file.h>
20 #include <android-base/unique_fd.h>
21 #include <linux/rtc.h>
22 #include <nativehelper/JNIHelp.h>
23 #include <utils/Log.h>
24 #include <utils/String8.h>
25
26 #include "jni.h"
27
28 namespace android {
29
30 class SystemClockImpl {
31 public:
SystemClockImpl(const std::string & rtc_dev)32 SystemClockImpl(const std::string &rtc_dev) : rtc_dev{rtc_dev} {}
33
34 int setTime(struct timeval *tv);
35
36 private:
37 std::string rtc_dev;
38 };
39
setTime(struct timeval * tv)40 int SystemClockImpl::setTime(struct timeval *tv) {
41 if (settimeofday(tv, NULL) == -1) {
42 ALOGV("settimeofday() failed: %s", strerror(errno));
43 return -1;
44 }
45
46 android::base::unique_fd fd{open(rtc_dev.c_str(), O_RDWR)};
47 if (!fd.ok()) {
48 ALOGE("Unable to open %s: %s", rtc_dev.c_str(), strerror(errno));
49 return -1;
50 }
51
52 struct tm tm;
53 if (!gmtime_r(&tv->tv_sec, &tm)) {
54 ALOGV("gmtime_r() failed: %s", strerror(errno));
55 return -1;
56 }
57
58 struct rtc_time rtc = {};
59 rtc.tm_sec = tm.tm_sec;
60 rtc.tm_min = tm.tm_min;
61 rtc.tm_hour = tm.tm_hour;
62 rtc.tm_mday = tm.tm_mday;
63 rtc.tm_mon = tm.tm_mon;
64 rtc.tm_year = tm.tm_year;
65 rtc.tm_wday = tm.tm_wday;
66 rtc.tm_yday = tm.tm_yday;
67 rtc.tm_isdst = tm.tm_isdst;
68 if (ioctl(fd, RTC_SET_TIME, &rtc) == -1) {
69 ALOGV("RTC_SET_TIME ioctl failed: %s", strerror(errno));
70 return -1;
71 }
72
73 return 0;
74 }
75
com_android_server_SystemClockTime_init(JNIEnv *,jobject)76 static jlong com_android_server_SystemClockTime_init(JNIEnv *, jobject) {
77 // Find the wall clock RTC. We expect this always to be /dev/rtc0, but
78 // check the /dev/rtc symlink first so that legacy devices that don't use
79 // rtc0 can add a symlink rather than need to carry a local patch to this
80 // code.
81 //
82 // TODO: if you're reading this in a world where all devices are using the
83 // GKI, you can remove the readlink and just assume /dev/rtc0.
84 std::string dev_rtc;
85 if (!android::base::Readlink("/dev/rtc", &dev_rtc)) {
86 dev_rtc = "/dev/rtc0";
87 }
88
89 std::unique_ptr<SystemClockImpl> system_clock{new SystemClockImpl(dev_rtc)};
90 return reinterpret_cast<jlong>(system_clock.release());
91 }
92
com_android_server_SystemClockTime_setTime(JNIEnv *,jobject,jlong nativeData,jlong millis)93 static jint com_android_server_SystemClockTime_setTime(JNIEnv *, jobject, jlong nativeData,
94 jlong millis) {
95 SystemClockImpl *impl = reinterpret_cast<SystemClockImpl *>(nativeData);
96
97 if (millis <= 0 || millis / 1000LL >= std::numeric_limits<time_t>::max()) {
98 return -1;
99 }
100
101 struct timeval tv;
102 tv.tv_sec = (millis / 1000LL);
103 tv.tv_usec = ((millis % 1000LL) * 1000LL);
104
105 ALOGD("Setting time of day to sec=%ld", tv.tv_sec);
106
107 int ret = impl->setTime(&tv);
108 if (ret < 0) {
109 ALOGW("Unable to set rtc to %ld: %s", tv.tv_sec, strerror(errno));
110 ret = -1;
111 }
112 return ret;
113 }
114
115 static const JNINativeMethod sMethods[] = {
116 /* name, signature, funcPtr */
117 {"init", "()J", (void *)com_android_server_SystemClockTime_init},
118 {"setTime", "(JJ)I", (void *)com_android_server_SystemClockTime_setTime},
119 };
120
register_com_android_server_SystemClockTime(JNIEnv * env)121 int register_com_android_server_SystemClockTime(JNIEnv *env) {
122 return jniRegisterNativeMethods(env, "com/android/server/SystemClockTime", sMethods,
123 NELEM(sMethods));
124 }
125
126 } /* namespace android */
127