platform: do not destroy the Platform instance on exit

Otherwise, secondary threads calling TEventQueue::wakeUp() could cause the application to crash on exit. We do it this way because there is no safe way to destroy the Platform orderly. In theory it could be done with thread_local shared pointers, but this appears to be broken in some compilers (e.g. MINGW).
magiblot · Oct 22, 2024 · cafeca0 · cafeca0
1 parent ca00eab
commit cafeca0
Show file tree

Hide file tree

Showing 5 changed files with 14 additions and 20 deletions.
diff --git a/include/tvision/internal/conctl.h b/include/tvision/internal/conctl.h
@@ -36,9 +36,7 @@ class ConsoleCtl
 
     // On Windows, the ConsoleCtl instance is created every time the alternate
     // screen buffer is enabled and it is destroyed when restoring the console.
-    // On Unix, the ConsoleCtl instance is created just once at the beginning
-    // of the program execution (in static initialization) and destroyed when
-    // exiting the program.
+    // On Unix, the ConsoleCtl instance is created just once.
 
     // Creates a global instance if none exists, and returns it.
     static ConsoleCtl &getInstance() noexcept;

diff --git a/include/tvision/internal/platform.h b/include/tvision/internal/platform.h
@@ -100,9 +100,10 @@ class Platform
 
     static int (*charWidth)(uint32_t) noexcept;
 
-    // Platform is a singleton. It gets created and destroyed by THardwareInfo.
+    // Platform is a singleton. It gets created by THardwareInfo, but it is
+    // never destroyed in order to support invocations to 'interruptEventWait'
+    // from secondary threads.
     Platform() noexcept;
-    ~Platform();
 
     // Note: explicit 'this' required by GCC 5.
     void setUpConsole() noexcept
@@ -138,6 +139,8 @@ class Platform
         { console.lock([&] (auto *c) { displayBuf.flushScreen(c->display); }); }
     TScreenCell *reloadScreenInfo() noexcept
         { return console.lock([&] (auto *c) { return displayBuf.reloadScreenInfo(c->display); }); }
+    void freeScreenBuffer() noexcept
+        { displayBuf.~DisplayBuffer(); new (&displayBuf) DisplayBuffer; }
 
     bool setClipboardText(TStringView text) noexcept
         { return console.lock([&] (auto *c) { return c->setClipboardText(text); }); }

diff --git a/source/platform/hardware.cpp b/source/platform/hardware.cpp
@@ -21,15 +21,15 @@ static tvision::Platform *platf;
 THardwareInfo::THardwareInfo() noexcept
 {
     using namespace tvision;
+    static int initPlatform =
+        (platf = new Platform(), (void) initPlatform, 0);
+
     pendingEvent = 0;
     alwaysFlush = getEnv<int>("TVISION_MAX_FPS", 0) < 0;
-    platf = new Platform();
 }
 
 THardwareInfo::~THardwareInfo()
 {
-    delete platf;
-    platf = nullptr;
 }
 
 void THardwareInfo::setCaretSize( ushort size ) noexcept { platf->setCaretSize(size); }
@@ -48,7 +48,7 @@ void THardwareInfo::screenWrite( ushort x, ushort y, TScreenCell *buf, DWORD len
         flushScreen();
 }
 TScreenCell *THardwareInfo::allocateScreenBuffer() noexcept { return platf->reloadScreenInfo(); }
-void THardwareInfo::freeScreenBuffer( TScreenCell * ) noexcept {}
+void THardwareInfo::freeScreenBuffer(TScreenCell *) noexcept { platf->freeScreenBuffer(); }
 DWORD THardwareInfo::getButtonCount() noexcept { return platf->getButtonCount(); }
 void THardwareInfo::cursorOn() noexcept { platf->cursorOn(); }
 void THardwareInfo::cursorOff() noexcept { platf->cursorOff(); }

diff --git a/source/platform/platform.cpp b/source/platform/platform.cpp
@@ -16,7 +16,7 @@ Platform *Platform::instance;
 
 // This is used by TText. It is a global function pointer (instead of an
 // instance method) so that it can be used regardless of whether the global
-// Platform instance has been created/destroyed or not.
+// Platform instance has been created or not.
 int (*Platform::charWidth)(uint32_t) noexcept = &Platform::initAndGetCharWidth;
 
 int Platform::initAndGetCharWidth(uint32_t wc) noexcept
@@ -55,15 +55,6 @@ Platform::Platform() noexcept
     initEncodingStuff();
 }
 
-Platform::~Platform()
-{
-    restoreConsole();
-#ifndef _WIN32
-    ConsoleCtl::destroyInstance();
-#endif
-    instance = nullptr;
-}
-
 void Platform::restoreConsole(ConsoleStrategy *&c) noexcept
 {
     if (c != &dummyConsole)
@@ -75,6 +66,9 @@ void Platform::restoreConsole(ConsoleStrategy *&c) noexcept
         SignalHandler::disable();
         delete c;
         c = &dummyConsole;
+#ifdef _WIN32
+        ConsoleCtl::destroyInstance();
+#endif
     }
 }
 

diff --git a/source/platform/win32con.cpp b/source/platform/win32con.cpp
@@ -110,7 +110,6 @@ Win32ConsoleStrategy::~Win32ConsoleStrategy()
     delete &input;
     SetConsoleCP(cpInput);
     SetConsoleOutputCP(cpOutput);
-    ConsoleCtl::destroyInstance();
 }
 
 bool Win32ConsoleStrategy::isAlive() noexcept