From 8dff17c1f979147b8091c8bee1f9f000cb266c77 Mon Sep 17 00:00:00 2001
From: JingMatrix <jingmatrix@gmail.com>
Date: Sun, 8 Dec 2024 23:38:20 +0100
Subject: [PATCH] Fix log watchdog logic

Log watchdog is meant to revert changes to the system prop
`persist.log.tag`, which sets global log level, see docs at
https://cs.android.com/android/platform/superproject/main/+/main:system/logging/logd/README.property

Current commit fixes the following:
1. avoid recast size value `-1` to unsigned integer type size_t;
2. allow the `Enable log watchdog` to removed added system prop and
   restart the watchdog forcely.
---
 daemon/src/main/jni/logcat.cpp | 43 ++++++++++++++++++++++------------
 1 file changed, 28 insertions(+), 15 deletions(-)

diff --git a/daemon/src/main/jni/logcat.cpp b/daemon/src/main/jni/logcat.cpp
index 12f0ca9b503..0b95be6f27c 100644
--- a/daemon/src/main/jni/logcat.cpp
+++ b/daemon/src/main/jni/logcat.cpp
@@ -7,8 +7,6 @@
 
 #include <array>
 #include <atomic>
-#include <chrono>
-#include <cinttypes>
 #include <functional>
 #include <string>
 #include <thread>
@@ -17,7 +15,7 @@ using namespace std::string_view_literals;
 using namespace std::chrono_literals;
 
 constexpr size_t kMaxLogSize = 4 * 1024 * 1024;
-constexpr size_t kLogBufferSize = 64 * 1024;
+constexpr long kLogBufferSize = 64 * 1024;
 
 namespace {
 constexpr std::array<char, ANDROID_LOG_SILENT + 1> kLogChar = {
@@ -32,7 +30,7 @@ constexpr std::array<char, ANDROID_LOG_SILENT + 1> kLogChar = {
     /*ANDROID_LOG_SILENT*/ 'S',
 };
 
-size_t ParseUint(const char *s) {
+long ParseUint(const char *s) {
     if (s[0] == '\0') return -1;
 
     while (isspace(*s)) {
@@ -63,7 +61,7 @@ size_t ParseUint(const char *s) {
     return static_cast<size_t>(result);
 }
 
-inline size_t GetByteProp(std::string_view prop, size_t def = -1) {
+inline long GetByteProp(std::string_view prop, long def = -1) {
     std::array<char, PROP_VALUE_MAX> buf{};
     if (__system_property_get(prop.data(), buf.data()) < 0) return def;
     return ParseUint(buf.data());
@@ -247,9 +245,17 @@ void Logcat::ProcessBuffer(struct log_msg *buf) {
         } else if (msg == "!!start_watchdog!!"sv) {
             enable_watchdog = true;
             enable_watchdog.notify_one();
+            EnsureLogWatchDog();
         } else if (msg == "!!stop_watchdog!!"sv) {
             enable_watchdog = false;
             enable_watchdog.notify_one();
+            std::system("resetprop -p --delete persist.logd.size");
+            std::system("resetprop -p --delete persist.logd.size.main");
+            std::system("resetprop -p --delete persist.logd.size.crash");
+
+            // Terminate the watchdog thread by exiting __system_property_wait firs firstt
+            std::system("setprop persist.log.tag V");
+            std::system("resetprop -p --delete persist.log.tag");
         }
     }
 }
@@ -259,14 +265,17 @@ void Logcat::EnsureLogWatchDog() {
     constexpr static auto kLogdTagProp = "persist.log.tag"sv;
     constexpr static auto kLogdMainSizeProp = "persist.logd.size.main"sv;
     constexpr static auto kLogdCrashSizeProp = "persist.logd.size.crash"sv;
-    constexpr static size_t kErr = -1;
-    std::thread watch_dog([this] {
+    constexpr static long kErr = -1;
+    std::thread watchdog([this] {
         while (true) {
-            enable_watchdog.wait(false);
+            enable_watchdog.wait(false);  // Blocking current thread until enable_watchdog is true;
             auto logd_size = GetByteProp(kLogdSizeProp);
             auto logd_tag = GetStrProp(kLogdTagProp);
             auto logd_main_size = GetByteProp(kLogdMainSizeProp);
             auto logd_crash_size = GetByteProp(kLogdCrashSizeProp);
+            Log("[LogWatchDog started] log.tag: " + logd_tag +
+                "; logd.[default, main, crash].size: [" + std::to_string(logd_size) + "," +
+                std::to_string(logd_main_size) + "," + std::to_string(logd_crash_size) + "]\n");
             if (!logd_tag.empty() ||
                 !((logd_main_size == kErr && logd_crash_size == kErr && logd_size != kErr &&
                    logd_size >= kLogBufferSize) ||
@@ -287,14 +296,20 @@ void Logcat::EnsureLogWatchDog() {
             }
             if (!__system_property_wait(pi, serial, &serial, nullptr)) break;
             if (pi != nullptr) {
-                if (enable_watchdog) Log("\nResetting log settings\n");
-            } else
+                if (enable_watchdog) {
+                    Log("\nProp persist.log.tag changed, resetting log settings\n");
+                } else {
+                    break;  // End current thread as expected
+                }
+            } else {
+                // log tag prop was not found; to avoid frequently trigger wait, sleep for a while
                 std::this_thread::sleep_for(1s);
-            // log tag prop was not found; to avoid frequently trigger wait, sleep for a while
+            }
         }
+        Log("[LogWatchDog stopped]\n");
     });
-    pthread_setname_np(watch_dog.native_handle(), "watchdog");
-    watch_dog.detach();
+    pthread_setname_np(watchdog.native_handle(), "watchdog");
+    watchdog.detach();
 }
 
 void Logcat::Run() {
@@ -303,8 +318,6 @@ void Logcat::Run() {
     RefreshFd(true);
     RefreshFd(false);
 
-    EnsureLogWatchDog();
-
     while (true) {
         std::unique_ptr<logger_list, decltype(&android_logger_list_free)> logger_list{
             android_logger_list_alloc(0, tail, 0), &android_logger_list_free};