Add sysprops for start & end of userspace reboot

There will be useful in debugging/logging events to statsd.

Also as part of this CL, sys.init.userspace_reboot.in_progress property
is now used as a mean of synchronization. It is set directly in
DoUserspaceReboot, to make sure that all the setprop actions triggered
by userspace-reboot-requested were processed.

Test: adb reboot userspace
Test: adb shell getprop sys.init.userspace_reboot.last_started
Test: adb shell getprop sys.init.userspace_reboot.last_finished
Bug: 135984674
Change-Id: I9debcd4f058e790855200d5295344dafb30e496a

init/builtins.cpp

@@ -65,6 +65,7 @@
 
 #include "action_manager.h"
 #include "bootchart.h"
+#include "builtin_arguments.h"
 #include "fscrypt_init_extensions.h"
 #include "init.h"
 #include "mount_namespace.h"
@@ -1216,6 +1217,15 @@ static Result<void> do_enter_default_mount_ns(const BuiltinArguments& args) {
     }
 }
 
+static Result<void> do_finish_userspace_reboot(const BuiltinArguments&) {
+    LOG(INFO) << "Userspace reboot successfully finished";
+    boot_clock::time_point now = boot_clock::now();
+    property_set("sys.init.userspace_reboot.last_finished",
+                 std::to_string(now.time_since_epoch().count()));
+    property_set(kUserspaceRebootInProgress, "0");
+    return {};
+}
+
 // Builtin-function-map start
 const BuiltinFunctionMap& GetBuiltinFunctionMap() {
     constexpr std::size_t kMax = std::numeric_limits<std::size_t>::max();
@@ -1237,6 +1247,7 @@ const BuiltinFunctionMap& GetBuiltinFunctionMap() {
         {"exec_background",         {1,     kMax, {false,  do_exec_background}}},
         {"exec_start",              {1,     1,    {false,  do_exec_start}}},
         {"export",                  {2,     2,    {false,  do_export}}},
+        {"finish_userspace_reboot", {0,     0,    {false,  do_finish_userspace_reboot}}},
         {"hostname",                {1,     1,    {true,   do_hostname}}},
         {"ifup",                    {1,     1,    {true,   do_ifup}}},
         {"init_user0",              {0,     0,    {false,  do_init_user0}}},

init/reboot.cpp

@@ -69,10 +69,13 @@
 
 using namespace std::literals;
 
+using android::base::boot_clock;
 using android::base::GetBoolProperty;
+using android::base::SetProperty;
 using android::base::Split;
 using android::base::Timer;
 using android::base::unique_fd;
+using android::base::WaitForProperty;
 using android::base::WriteStringToFile;
 
 namespace android {
@@ -728,16 +731,21 @@ static Result<void> UnmountAllApexes() {
 
 static Result<void> DoUserspaceReboot() {
     LOG(INFO) << "Userspace reboot initiated";
+    boot_clock::time_point now = boot_clock::now();
+    property_set("sys.init.userspace_reboot.last_started",
+                 std::to_string(now.time_since_epoch().count()));
     auto guard = android::base::make_scope_guard([] {
         // Leave shutdown so that we can handle a full reboot.
         LeaveShutdown();
         trigger_shutdown("reboot,abort-userspace-reboot");
     });
-    // Triggering userspace-reboot-requested will result in a bunch of set_prop
+    // Triggering userspace-reboot-requested will result in a bunch of setprop
     // actions. We should make sure, that all of them are propagated before
-    // proceeding with userspace reboot.
+    // proceeding with userspace reboot. Synchronously setting kUserspaceRebootInProgress property
-    // TODO(b/135984674): implement proper synchronization logic.
+    // is not perfect, but it should do the trick.
-    std::this_thread::sleep_for(500ms);
+    if (property_set(kUserspaceRebootInProgress, "1") != 0) {
+        return Error() << "Failed to set property " << kUserspaceRebootInProgress;
+    }
     EnterShutdown();
     std::vector<Service*> stop_first;
     // Remember the services that were enabled. We will need to manually enable them again otherwise

init/reboot.h

@@ -22,6 +22,8 @@
 namespace android {
 namespace init {
 
+static const constexpr char* kUserspaceRebootInProgress = "sys.init.userspace_reboot.in_progress";
+
 // Parses and handles a setprop sys.powerctl message.
 void HandlePowerctlMessage(const std::string& command);
 

rootdir/init.rc

@@ -925,7 +925,6 @@ on init && property:ro.debuggable=1
 
 on userspace-reboot-requested
   # TODO(b/135984674): reset all necessary properties here.
-  setprop sys.init.userspace_reboot_in_progress 1
   setprop sys.boot_completed 0
   setprop sys.init.updatable_crashing 0
   setprop apexd.status ""
@@ -945,3 +944,6 @@ on userspace-reboot-resume
   trigger zygote-start
   trigger early-boot
   trigger boot
+
+on property:sys.boot_completed=1 && property:sys.init.userspace_reboot.in_progress=1
+  finish_userspace_reboot