From 2c142d77afb37fb9ce5eace62d9f054013b3a2ee Mon Sep 17 00:00:00 2001
From: falkTX <falktx@falktx.com>
Date: Mon, 11 Jan 2021 15:47:34 +0000
Subject: [PATCH] Clear PID when child process ends

---
 source/backend/plugin/CarlaPluginBridge.cpp     |  2 +-
 source/backend/plugin/CarlaPluginJack.cpp       |  2 +-
 source/backend/plugin/CarlaPluginLADSPADSSI.cpp |  2 +-
 source/modules/water/threads/ChildProcess.cpp   | 16 ++++++++++++----
 source/modules/water/threads/ChildProcess.h     |  4 ++--
 5 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/source/backend/plugin/CarlaPluginBridge.cpp b/source/backend/plugin/CarlaPluginBridge.cpp
index f6d1be68f..82757d479 100644
--- a/source/backend/plugin/CarlaPluginBridge.cpp
+++ b/source/backend/plugin/CarlaPluginBridge.cpp
@@ -351,7 +351,7 @@ protected:
         else
         {
             // forced quit, may have crashed
-            if (fProcess->getExitCode() != 0 /*|| fProcess->exitStatus() == QProcess::CrashExit*/)
+            if (fProcess->getExitCodeAndClearPID() != 0)
             {
                 carla_stderr("CarlaPluginBridgeThread::run() - bridge crashed");
 
diff --git a/source/backend/plugin/CarlaPluginJack.cpp b/source/backend/plugin/CarlaPluginJack.cpp
index 2abcc7577..928509075 100644
--- a/source/backend/plugin/CarlaPluginJack.cpp
+++ b/source/backend/plugin/CarlaPluginJack.cpp
@@ -432,7 +432,7 @@ protected:
             else
             {
                 // forced quit, may have crashed
-                if (fProcess->getExitCode() != 0 /*|| fProcess->exitStatus() == QProcess::CrashExit*/)
+                if (fProcess->getExitCodeAndClearPID() != 0)
                 {
                     carla_stderr("CarlaPluginJackThread::run() - application crashed");
 
diff --git a/source/backend/plugin/CarlaPluginLADSPADSSI.cpp b/source/backend/plugin/CarlaPluginLADSPADSSI.cpp
index 86494b3be..8e46b0860 100644
--- a/source/backend/plugin/CarlaPluginLADSPADSSI.cpp
+++ b/source/backend/plugin/CarlaPluginLADSPADSSI.cpp
@@ -225,7 +225,7 @@ public:
                     carla_stdout("CarlaThreadDSSIUI::run() - UI auto-closed successfully");
                 }
             }
-            else if (fProcess->getExitCode() != 0 /*|| fProcess->exitStatus() == QProcess::CrashExit*/)
+            else if (fProcess->getExitCodeAndClearPID() != 0)
                 carla_stderr("CarlaThreadDSSIUI::run() - UI crashed while running");
             else
                 carla_stdout("CarlaThreadDSSIUI::run() - UI closed cleanly");
diff --git a/source/modules/water/threads/ChildProcess.cpp b/source/modules/water/threads/ChildProcess.cpp
index 04f987062..2ca1b9514 100644
--- a/source/modules/water/threads/ChildProcess.cpp
+++ b/source/modules/water/threads/ChildProcess.cpp
@@ -54,9 +54,15 @@ public:
     }
 
     ~ActiveProcess()
+    {
+        closeProcessInfo();
+    }
+
+    void closeProcessInfo() noexcept
     {
         if (ok)
         {
+            ok = false;
             CloseHandle (processInfo.hThread);
             CloseHandle (processInfo.hProcess);
         }
@@ -88,10 +94,11 @@ public:
         return TerminateProcess (processInfo.hProcess, 0) != FALSE;
     }
 
-    uint32 getExitCode() const noexcept
+    uint32 getExitCodeAndClearPID() noexcept
     {
         DWORD exitCode = 0;
         GetExitCodeProcess (processInfo.hProcess, &exitCode);
+        closeProcessInfo();
         return (uint32) exitCode;
     }
 
@@ -200,12 +207,13 @@ public:
         return ::kill (childPID, SIGTERM) == 0;
     }
 
-    uint32 getExitCode() const noexcept
+    uint32 getExitCodeAndClearPID() noexcept
     {
         if (childPID != 0)
         {
             int childState = 0;
             const int pid = waitpid (childPID, &childState, WNOHANG);
+            childPID = 0;
 
             if (pid >= 0 && WIFEXITED (childState))
                 return WEXITSTATUS (childState);
@@ -246,9 +254,9 @@ bool ChildProcess::terminate()
     return activeProcess == nullptr || activeProcess->terminateProcess();
 }
 
-uint32 ChildProcess::getExitCode() const
+uint32 ChildProcess::getExitCodeAndClearPID()
 {
-    return activeProcess != nullptr ? activeProcess->getExitCode() : 0;
+    return activeProcess != nullptr ? activeProcess->getExitCodeAndClearPID() : 0;
 }
 
 bool ChildProcess::waitForProcessToFinish (const int timeoutMs)
diff --git a/source/modules/water/threads/ChildProcess.h b/source/modules/water/threads/ChildProcess.h
index 314a5db89..2f8c77a6f 100644
--- a/source/modules/water/threads/ChildProcess.h
+++ b/source/modules/water/threads/ChildProcess.h
@@ -81,8 +81,8 @@ public:
     /** Blocks until the process is no longer running. */
     bool waitForProcessToFinish (int timeoutMs);
 
-    /** If the process has finished, this returns its exit code. */
-    uint32 getExitCode() const;
+    /** If the process has finished, this returns its exit code and also clears assigned PID. */
+    uint32 getExitCodeAndClearPID();
 
     /** Attempts to kill the child process.
         Returns true if it succeeded. Trying to read from the process after calling this may