From 6fc09324ab4ead2b8896f9f2cf1fbb1bce75e2d5 Mon Sep 17 00:00:00 2001
From: scorpion-26 <dev.scorpion26@gmail.com>
Date: Fri, 15 Mar 2024 19:30:38 +0100
Subject: [PATCH] Only allow sequential runs of package checking

If the current monitor would quickly change, GetOutdatedPackagesAsync
would be called while the previous instance is still running, which
caused crashes. Now, GetOutdatedPackagesAsync only uses one
instance/callback a time.
---
 src/System.cpp | 64 +++++++++++++++++++++++++++++---------------------
 src/System.h   |  1 +
 2 files changed, 38 insertions(+), 27 deletions(-)

diff --git a/src/System.cpp b/src/System.cpp
index c627840..d041bfb 100644
--- a/src/System.cpp
+++ b/src/System.cpp
@@ -576,17 +576,28 @@ namespace System
 
     void GetOutdatedPackagesAsync(std::function<void(uint32_t)>&& returnVal)
     {
+        static bool currentlyRunning = false;
+        static std::function<void(uint32_t)> handlerFunction;
         static std::mutex configMutex;
-        configMutex.lock();
-        if (!RuntimeConfig::Get().hasPackagesScript)
+
         {
-            configMutex.unlock();
-            return; // Don't bother
+            std::scoped_lock<std::mutex> lock(configMutex);
+            if (!RuntimeConfig::Get().hasPackagesScript)
+            {
+                return; // Don't bother
+            }
+            handlerFunction = returnVal;
+            if (currentlyRunning)
+            {
+                // Thread is running, only update handler
+                return;
+            }
+
+            currentlyRunning = true;
         }
-        configMutex.unlock();
 
         std::thread(
-            [](std::function<void(uint32_t)> returnVal)
+            [&]()
             {
                 // We need a pipe, since there is no "libpacman". This should only be called every so often anyways
                 std::string number;
@@ -601,29 +612,28 @@ namespace System
                 ASSERT(feof(pipe), "GetOutdatedPackages: Cannot read to eof!");
 
                 int exitCode = pclose(pipe) / 256;
-                if (exitCode != 0)
                 {
-                    configMutex.lock();
-                    // Invalid script/error
-                    LOG("GetOutdatedPackages: Invalid command. Disabling package widget!");
-                    RuntimeConfig::Get().hasPackagesScript = false;
-                    configMutex.unlock();
-                    return;
+                    std::scoped_lock<std::mutex> lock(configMutex);
+                    if (exitCode != 0)
+                    {
+                        // Invalid script/error
+                        LOG("GetOutdatedPackages: Invalid command. Disabling package widget!");
+                        RuntimeConfig::Get().hasPackagesScript = false;
+                        currentlyRunning = false;
+                        return;
+                    }
+                    try
+                    {
+                        handlerFunction(std::stoul(buf));
+                    }
+                    catch (std::invalid_argument&)
+                    {
+                        LOG("GetOutdatedPackages: Invalid output of the package script. Disabling package widget!");
+                        RuntimeConfig::Get().hasPackagesScript = false;
+                    }
+                    currentlyRunning = false;
                 }
-                try
-                {
-                    returnVal(std::stoul(buf));
-                }
-                catch (std::invalid_argument&)
-                {
-                    configMutex.lock();
-                    LOG("GetOutdatedPackages: Invalid output of the package script. Disabling package widget!");
-                    RuntimeConfig::Get().hasPackagesScript = false;
-                    configMutex.unlock();
-                    return;
-                }
-            },
-            std::move(returnVal))
+            })
             .detach();
     }
 
diff --git a/src/System.h b/src/System.h
index 89f6b64..e078198 100644
--- a/src/System.h
+++ b/src/System.h
@@ -108,6 +108,7 @@ namespace System
     // Bytes per second download. dx is time since last call. Will always return 0 on first run
     double GetNetworkBpsDownload(double dt);
 
+    // This can only be called one at a time. If it is already running it is assumed, that the old handler is no longer valid.
     void GetOutdatedPackagesAsync(std::function<void(uint32_t)>&& returnVal);
 
     std::string GetTime();