From ee016ce0b3cecde031c1d5463edcc1473b63bc39 Mon Sep 17 00:00:00 2001
From: Mark Salyzyn <salyzyn@google.com>
Date: Thu, 23 May 2019 10:00:34 -0700
Subject: [PATCH] bootstat: enhance last reboot reason property with file
 backing

Helps with support of recovery and rollback boot reason history, by
also using /metadata/bootstat/persist.sys.boot.reason to file the
reboot reason.

Test: manual
Bug: 129007837
Change-Id: Id1d21c404067414847bef14a0c43f70cafe1a3e2
---
 bootstat/bootstat.cpp                     | 11 +++++++++--
 init/reboot.cpp                           |  1 +
 libcutils/include/cutils/android_reboot.h |  1 +
 rootdir/init.rc                           |  1 +
 4 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/bootstat/bootstat.cpp b/bootstat/bootstat.cpp
index 9ffe5dd34..a9c1676d9 100644
--- a/bootstat/bootstat.cpp
+++ b/bootstat/bootstat.cpp
@@ -870,6 +870,7 @@ bool addKernelPanicSubReason(const std::string& content, std::string& ret) {
 
 const char system_reboot_reason_property[] = "sys.boot.reason";
 const char last_reboot_reason_property[] = LAST_REBOOT_REASON_PROPERTY;
+const char last_reboot_reason_file[] = LAST_REBOOT_REASON_FILE;
 const char last_last_reboot_reason_property[] = "sys.boot.reason.last";
 constexpr size_t history_reboot_reason_size = 4;
 const char history_reboot_reason_property[] = LAST_REBOOT_REASON_PROPERTY ".history";
@@ -1059,7 +1060,9 @@ std::string BootReasonStrToReason(const std::string& boot_reason) {
     if (isBluntRebootReason(ret)) {
       // Content buffer no longer will have console data. Beware if more
       // checks added below, that depend on parsing console content.
-      content = android::base::GetProperty(last_reboot_reason_property, "");
+      if (!android::base::ReadFileToString(last_reboot_reason_file, &content)) {
+        content = android::base::GetProperty(last_reboot_reason_property, "");
+      }
       transformReason(content);
 
       // Anything in last is better than 'super-blunt' reboot or shutdown.
@@ -1233,7 +1236,10 @@ void SetSystemBootReason() {
   // Record the scrubbed system_boot_reason to the property
   BootReasonAddToHistory(system_boot_reason);
   // Shift last_reboot_reason_property to last_last_reboot_reason_property
-  auto last_boot_reason = android::base::GetProperty(last_reboot_reason_property, "");
+  std::string last_boot_reason;
+  if (!android::base::ReadFileToString(last_reboot_reason_file, &last_boot_reason)) {
+    last_boot_reason = android::base::GetProperty(last_reboot_reason_property, "");
+  }
   if (last_boot_reason.empty() || isKernelRebootReason(system_boot_reason)) {
     last_boot_reason = system_boot_reason;
   } else {
@@ -1241,6 +1247,7 @@ void SetSystemBootReason() {
   }
   android::base::SetProperty(last_last_reboot_reason_property, last_boot_reason);
   android::base::SetProperty(last_reboot_reason_property, "");
+  unlink(last_reboot_reason_file);
 }
 
 // Gets the boot time offset. This is useful when Android is running in a
diff --git a/init/reboot.cpp b/init/reboot.cpp
index 38e822711..97d40b749 100644
--- a/init/reboot.cpp
+++ b/init/reboot.cpp
@@ -548,6 +548,7 @@ static void DoReboot(unsigned int cmd, const std::string& reason, const std::str
         skip = strlen("reboot,");
     }
     SetProperty(LAST_REBOOT_REASON_PROPERTY, reason.c_str() + skip);
+    WriteStringToFile(reason.c_str() + skip, LAST_REBOOT_REASON_FILE);
     sync();
 
     bool is_thermal_shutdown = cmd == ANDROID_RB_THERMOFF;
diff --git a/libcutils/include/cutils/android_reboot.h b/libcutils/include/cutils/android_reboot.h
index cd27eef88..24e32d560 100644
--- a/libcutils/include/cutils/android_reboot.h
+++ b/libcutils/include/cutils/android_reboot.h
@@ -31,6 +31,7 @@ __BEGIN_DECLS
 
 /* Android reboot reason stored in this property */
 #define LAST_REBOOT_REASON_PROPERTY "persist.sys.boot.reason"
+#define LAST_REBOOT_REASON_FILE "/metadata/bootstat/" LAST_REBOOT_REASON_PROPERTY
 
 /* Reboot or shutdown the system.
  * This call uses ANDROID_RB_PROPERTY to request reboot to init process.
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 782f96701..77860f625 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -496,6 +496,7 @@ on post-fs
     mkdir /metadata/vold
     chmod 0700 /metadata/vold
     mkdir /metadata/password_slots 0771 root system
+    mkdir /metadata/bootstat 0750 system log
     mkdir /metadata/ota 0700 root system
     mkdir /metadata/ota/snapshots 0700 root system