init: Allows shutting down cleanly.

When ro.build.shutdown_timeout is set, init will send a SIGTERM signal to
all services on reboot. The normal shutdown process will continue once
all services have exited or after the shutdown timeout
(ro.build.shutdown_timeout).

If ro.build.shutdown_timeout is not set, we assume a 0s timeout.

Bug: 26216447
Test: manual: Ask to reboot. All services exit cleanly.

Change-Id: If921f6e8d87211e500ac9fa86f3e1eabe02d18cf

1 files changed, 40 insertions, 0 deletions

diff --git a/init/builtins.cpp b/init/builtins.cpp
index 10f9d8171..d2291bb50 100644
--- a/init/builtins.cpp
+++ b/init/builtins.cpp
@@ -39,6 +39,7 @@
 #include <selinux/label.h>
 
 #include <fs_mgr.h>
+#include <android-base/parseint.h>
 #include <android-base/stringprintf.h>
 #include <cutils/partition_utils.h>
 #include <cutils/android_reboot.h>
@@ -53,6 +54,7 @@
 #include "log.h"
 #include "property_service.h"
 #include "service.h"
+#include "signal_handler.h"
 #include "util.h"
 
 #define chmod DO_NOT_USE_CHMOD_USE_FCHMODAT_SYMLINK_NOFOLLOW
@@ -62,6 +64,8 @@
 // System call provided by bionic but not in any header file.
 extern "C" int init_module(void *, unsigned long, const char *);
 
+static const int kTerminateServiceDelayMicroSeconds = 50000;
+
 static int insmod(const char *filename, const char *options) {
     std::string module;
     if (!read_file(filename, &module)) {
@@ -608,6 +612,42 @@ static int do_powerctl(const std::vector<std::string>& args) {
         return -EINVAL;
     }
 
+    std::string timeout = property_get("ro.build.shutdown_timeout");
+    unsigned int delay = 0;
+
+    if (android::base::ParseUint(timeout.c_str(), &delay) && delay > 0) {
+        Timer t;
+        // Ask all services to terminate.
+        ServiceManager::GetInstance().ForEachService(
+            [] (Service* s) { s->Terminate(); });
+
+        while (t.duration() < delay) {
+            ServiceManager::GetInstance().ReapAnyOutstandingChildren();
+
+            int service_count = 0;
+            ServiceManager::GetInstance().ForEachService(
+                [&service_count] (Service* s) {
+                    // Count the number of services running.
+                    // Exclude the console as it will ignore the SIGTERM signal
+                    // and not exit.
+                    // Note: SVC_CONSOLE actually means "requires console" but
+                    // it is only used by the shell.
+                    if (s->pid() != 0 && (s->flags() & SVC_CONSOLE) == 0) {
+                        service_count++;
+                    }
+                });
+
+            if (service_count == 0) {
+                // All terminable services terminated. We can exit early.
+                break;
+            }
+
+            // Wait a bit before recounting the number or running services.
+            usleep(kTerminateServiceDelayMicroSeconds);
+        }
+        NOTICE("Terminating running services took %.02f seconds", t.duration());
+    }
+
     return android_reboot_with_callback(cmd, 0, reboot_target,
                                         callback_on_ro_remount);
 }