From dbafdf67440947e6bfb7f1a80c246641614b74e1 Mon Sep 17 00:00:00 2001
From: Thulinma <jaron@vietors.com>
Date: Fri, 19 Mar 2021 22:36:27 +0100
Subject: [PATCH] Correct handling of reaper thread in forking binaries

---
 lib/procs.cpp                 | 22 ++++++++++++++++++++++
 lib/procs.h                   |  2 ++
 lib/util.cpp                  |  3 +++
 src/controller/controller.cpp |  5 +++--
 src/input/input.cpp           | 11 ++++++-----
 5 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/lib/procs.cpp b/lib/procs.cpp
index 851014ab..3ce41860 100644
--- a/lib/procs.cpp
+++ b/lib/procs.cpp
@@ -157,6 +157,28 @@ void Util::Procs::exit_handler() {
   FAIL_MSG("Giving up with %d children left.", (int)listcopy.size());
 }
 
+// Joins the reaper thread, if any, before a fork
+void Util::Procs::fork_prepare(){
+  tthread::lock_guard<tthread::mutex> guard(plistMutex);
+  if (handler_set){
+    thread_handler = false;
+    if (reaper_thread){
+      reaper_thread->join();
+      delete reaper_thread;
+      reaper_thread = 0;
+    }
+  }
+}
+
+/// Restarts reaper thread if it was joined
+void Util::Procs::fork_complete(){
+  tthread::lock_guard<tthread::mutex> guard(plistMutex);
+  if (handler_set){
+    thread_handler = true;
+    reaper_thread = new tthread::thread(grim_reaper, 0);
+  }
+}
+
 /// Sets up exit and childsig handlers.
 /// Spawns grim_reaper. exit handler despawns grim_reaper
 /// Called by every Start* function.
diff --git a/lib/procs.h b/lib/procs.h
index e7edb4d0..05eb484a 100644
--- a/lib/procs.h
+++ b/lib/procs.h
@@ -26,6 +26,8 @@ namespace Util {
       static bool childRunning(pid_t p);
       static tthread::thread * reaper_thread;
       static bool handler_set; ///< If true, the sigchld handler has been setup.
+      static void fork_prepare();
+      static void fork_complete();
       static void setHandler();
       static std::string getOutputOf(char * const * argv);
       static std::string getOutputOf(std::deque<std::string> & argDeq);
diff --git a/lib/util.cpp b/lib/util.cpp
index 2a4402dc..ebae4f77 100644
--- a/lib/util.cpp
+++ b/lib/util.cpp
@@ -245,8 +245,10 @@ namespace Util{
     int pipeErr[2];
     if (pipe(pipeErr) >= 0){
       //Start reading log messages from the unnamed pipe
+      Util::Procs::fork_prepare();
       pid_t pid = fork();
       if (pid == 0) { //child
+        Util::Procs::fork_complete();
         close(pipeErr[1]);               // close the unneeded pipe file descriptor
         //Close all sockets in the socketList
         for (std::set<int>::iterator it = Util::Procs::socketList.begin(); it != Util::Procs::socketList.end(); ++it){
@@ -264,6 +266,7 @@ namespace Util{
         Util::logParser(pipeErr[0], true_stderr, isatty(true_stderr));
         exit(0);
       }
+      Util::Procs::fork_complete();
       if (pid == -1){
         FAIL_MSG("Failed to fork child process for log handling!");
       }else{
diff --git a/src/controller/controller.cpp b/src/controller/controller.cpp
index 60d07b8e..2a606cb0 100644
--- a/src/controller/controller.cpp
+++ b/src/controller/controller.cpp
@@ -596,10 +596,10 @@ int main(int argc, char **argv){
   Controller::conf.activate();
   uint64_t reTimer = 0;
   while (Controller::conf.is_active){
+    Util::Procs::fork_prepare();
     pid_t pid = fork();
     if (pid == 0){
-      Util::Procs::handler_set = false;
-      Util::Procs::reaper_thread = 0;
+      Util::Procs::fork_complete();
       {
         struct sigaction new_action;
         new_action.sa_sigaction = handleUSR1;
@@ -609,6 +609,7 @@ int main(int argc, char **argv){
       }
       return main_loop(argc, argv);
     }
+    Util::Procs::fork_complete();
     if (pid == -1){
       FAIL_MSG("Unable to spawn controller process!");
       return 2;
diff --git a/src/input/input.cpp b/src/input/input.cpp
index f5f3c8e6..30805bcc 100644
--- a/src/input/input.cpp
+++ b/src/input/input.cpp
@@ -310,11 +310,8 @@ namespace Mist {
         streamStatus.master = false;
         if (streamStatus){streamStatus.mapped[0] = STRMSTAT_INIT;}
       }
-      //Abandon all semaphores, ye who enter here.
-      playerLock.abandon();
-      pullLock.abandon();
-      if (!preRun()){return 0;}
-      int ret = run();
+      int ret = 0;
+      if (preRun()){ret = run();}
       if (playerLock){
         playerLock.unlink();
         char pageName[NAME_BUFFER_SIZE];
@@ -322,14 +319,17 @@ namespace Mist {
         streamStatus.init(pageName, 1, true, false);
         streamStatus.close();
       }
+      playerLock.unlink();
       pullLock.unlink();
       return ret;
     }
 
     uint64_t reTimer = 0;
     while (config->is_active){
+      Util::Procs::fork_prepare();
       pid_t pid = fork();
       if (pid == 0){
+        Util::Procs::fork_complete();
         if (playerLock){
           //Re-init streamStatus, previously closed
           char pageName[NAME_BUFFER_SIZE];
@@ -344,6 +344,7 @@ namespace Mist {
         if (!preRun()){return 0;}
         return run();
       }
+      Util::Procs::fork_complete();
       if (pid == -1){
         FAIL_MSG("Unable to spawn input process");
         //We failed. Release the kra... semaphores!