Refactor/back stack lifecycle

Makefile

@@ -36,7 +36,7 @@ VENDORED_LIBS =
 endif
 CXXFLAGS = -std=c++11 -Os $(SDL_CFLAGS) -DMOD_VERSION=\"v$(MOD_VER)\"
 LDLIBS = $(SDL_LIBS)
-SOURCES = src/main.cpp src/command.cpp src/download_screen.cpp src/localization.cpp src/framework/badge.cpp src/framework/dialog.cpp src/framework/sdl_context.cpp src/framework/texture.cpp src/framework/controller.cpp src/framework/powerwatch.cpp src/framework/draw_helpers.cpp src/framework/utf8.cpp src/framework/font8x8_lookup.cpp src/framework/uitheme.cpp src/framework/list_jump.cpp
+SOURCES = src/main.cpp src/back_stack.cpp src/command.cpp src/download_screen.cpp src/localization.cpp src/framework/badge.cpp src/framework/dialog.cpp src/framework/sdl_context.cpp src/framework/texture.cpp src/framework/controller.cpp src/framework/powerwatch.cpp src/framework/draw_helpers.cpp src/framework/utf8.cpp src/framework/font8x8_lookup.cpp src/framework/uitheme.cpp src/framework/list_jump.cpp
 OBJECTS = $(SOURCES:.cpp=.o)
 ALL_OBJECTS = $(OBJECTS) src/daemon.o src/mod_uninstall.o src/save_manager.o src/standby_watchdog.o src/gen_splash.o src/change_combo.o
 

mod/etc/options_menu/save_manager/launch_save_manager.sh

@@ -29,11 +29,14 @@ remaining="${OM_BACK_STACK%;*}"
 command_path="${entry%%,*}"
 rest="${entry#*,}"
 script_path="${rest%%,*}"
-title_key="${rest#*,}"
+title_rest="${rest#*,}"
+title_key="${title_rest%%,*}"
+marker=""
+[ "$title_rest" != "$title_key" ] && marker="${title_rest#*,}"
 
 usleep 50000
-if [ -n "$script_path" ]; then
-  OM_BACK_STACK="$remaining" "$options_path/options" --commandPath "$command_path" --scriptPath "$script_path" --title "$title_key"
-else
-  OM_BACK_STACK="$remaining" "$options_path/options" --commandPath "$command_path" --title "$title_key"
-fi
+set -- --commandPath "$command_path"
+[ -n "$script_path" ] && set -- "$@" --scriptPath "$script_path"
+set -- "$@" --title "$title_key"
+[ -n "$marker" ] && set -- "$@" --selectedMarker "$marker"
+OM_BACK_STACK="$remaining" "$options_path/options" "$@"

src/application_lifecycle.h

@@ -0,0 +1,97 @@
+//  Copyright (C) 2026 DefKorns
+//
+//  This program is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU General Public License
+//  as published by the Free Software Foundation; either version 3
+//  of the License, or (at your option) any later version.
+
+#ifndef APPLICATION_LIFECYCLE_H_
+#define APPLICATION_LIFECYCLE_H_
+
+#include <csignal>
+#include <cstdlib>
+#include <string>
+#include <utility>
+#include <sys/types.h>
+#include <unistd.h>
+
+extern char ** environ;
+
+enum class ExitAction { Resume, Leave };
+
+// Resume runs from the destructor, after main()'s locals (SDL) are released.
+class ApplicationLifecycle
+{
+public:
+    ApplicationLifecycle() = default;
+    ApplicationLifecycle(const ApplicationLifecycle &) = delete;
+    ApplicationLifecycle & operator=(const ApplicationLifecycle &) = delete;
+
+    ~ApplicationLifecycle()
+    {
+        if(action == ExitAction::Resume && !resumed && !script.empty())
+        {
+            resumed = true;
+            State().resume = 0;
+            std::system(("/bin/sh " + script).c_str());
+        }
+    }
+
+    void SetResumeScript(std::string path)
+    {
+        script = std::move(path);
+        State().argv[1] = script.c_str();
+    }
+
+    void Decide(ExitAction decision)
+    {
+        action = decision;
+        State().resume = decision == ExitAction::Resume ? 1 : 0;
+    }
+
+    // handler may only call async-signal-safe functions; vfork skips the atfork handlers
+    void InstallSignalHandlers()
+    {
+        struct sigaction sa;
+        sa.sa_handler = OnTerminate;
+        sigemptyset(&sa.sa_mask);
+        sa.sa_flags = 0;
+        sigaction(SIGTERM, &sa, nullptr);
+        sigaction(SIGHUP, &sa, nullptr);
+    }
+
+private:
+    static void OnTerminate(int sig)
+    {
+        SignalState & state = State();
+        if(!state.fired && state.resume && state.argv[1])
+        {
+            state.fired = 1;
+            if(vfork() == 0)
+            {
+                execve("/bin/sh", const_cast<char * const *>(state.argv), environ);
+                _exit(127);
+            }
+        }
+        _exit(128 + sig);
+    }
+
+    struct SignalState
+    {
+        const char * argv[3] = { "sh", nullptr, nullptr };
+        volatile sig_atomic_t resume = 1;
+        volatile sig_atomic_t fired = 0;
+    };
+
+    static SignalState & State()
+    {
+        static SignalState state;
+        return state;
+    }
+
+    std::string script;
+    ExitAction action = ExitAction::Resume;
+    bool resumed = false;
+};
+
+#endif

src/back_stack.cpp

@@ -0,0 +1,74 @@
+//  Copyright (C) 2026 DefKorns
+//
+//  This program is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU General Public License
+//  as published by the Free Software Foundation; either version 3
+//  of the License, or (at your option) any later version.
+
+#include "back_stack.h"
+
+#include <vector>
+
+namespace back_stack
+{
+    std::string MakeEntry(const std::string & commandPath, const std::string & scriptPath,
+                          const std::string & titleKey, const std::string & marker)
+    {
+        return commandPath + "," + scriptPath + "," + titleKey + (marker.empty() ? "" : "," + marker);
+    }
+
+    std::string PopIfLast(const std::string & stack, const std::string & entry)
+    {
+        const size_t lastSep = stack.find_last_of(';');
+        const std::string last = stack.empty() ? "" : (lastSep == std::string::npos ? stack : stack.substr(lastSep + 1));
+        if(last != entry)
+            return stack;
+        return lastSep == std::string::npos ? "" : stack.substr(0, lastSep);
+    }
+
+    std::string Push(const std::string & stack, const std::string & entry)
+    {
+        return stack.empty() ? entry : stack + ";" + entry;
+    }
+
+    std::string BackCommand(const std::string & stack, const std::string & optionsLocation)
+    {
+        if(stack.empty())
+            return "";
+
+        std::vector<std::string> entries;
+        for(size_t start = 0; start < stack.size();)
+        {
+            size_t sep = stack.find(';', start);
+            if(sep == std::string::npos)
+                sep = stack.size();
+            entries.push_back(stack.substr(start, sep - start));
+            start = sep + 1;
+        }
+        const std::string lastEntry = entries.back();
+        entries.pop_back();
+        std::string remainingStack;
+        for(size_t i = 0; i < entries.size(); ++i)
+        {
+            if(i)
+                remainingStack += ";";
+            remainingStack += entries[i];
+        }
+
+        const size_t c1 = lastEntry.find(',');
+        const size_t c2 = c1 == std::string::npos ? c1 : lastEntry.find(',', c1 + 1);
+        if(c2 == std::string::npos)
+            return "";
+
+        const std::string backPath = lastEntry.substr(0, c1);
+        const std::string backScriptPath = lastEntry.substr(c1 + 1, c2 - c1 - 1);
+        const size_t c3 = lastEntry.find(',', c2 + 1);
+        const std::string backTitleKey = lastEntry.substr(c2 + 1, c3 == std::string::npos ? std::string::npos : c3 - c2 - 1);
+        const std::string backMarker = c3 == std::string::npos ? "" : lastEntry.substr(c3 + 1);
+
+        return "usleep 50000 && OM_BACK_STACK=\"" + remainingStack + "\" " + optionsLocation + "options --commandPath " + backPath
+            + (backScriptPath.empty() ? "" : " --scriptPath " + backScriptPath)
+            + " --title \"" + backTitleKey + "\""
+            + (backMarker.empty() ? "" : " --selectedMarker \"" + backMarker + "\"") + " &";
+    }
+}

src/back_stack.h

@@ -0,0 +1,27 @@
+//  Copyright (C) 2026 DefKorns
+//
+//  This program is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU General Public License
+//  as published by the Free Software Foundation; either version 3
+//  of the License, or (at your option) any later version.
+
+#ifndef BACK_STACK_H_
+#define BACK_STACK_H_
+
+#include <string>
+
+// OM_BACK_STACK is ';'-separated entries of "commandPath,scriptPath,titleKey[,marker]".
+namespace back_stack
+{
+    std::string MakeEntry(const std::string & commandPath, const std::string & scriptPath,
+                          const std::string & titleKey, const std::string & marker);
+
+    std::string PopIfLast(const std::string & stack, const std::string & entry);
+
+    std::string Push(const std::string & stack, const std::string & entry);
+
+    // empty when the stack is empty or the last entry is malformed
+    std::string BackCommand(const std::string & stack, const std::string & optionsLocation);
+}
+
+#endif

src/main.cpp

@@ -14,6 +14,8 @@
 #include "framework/powerwatch.h"
 #include "framework/draw_helpers.h"
 #include "framework/utf8.h"
+#include "application_lifecycle.h"
+#include "back_stack.h"
 #include "command.h"
 #include "download_screen.h"
 #include "localization.h"
@@ -50,22 +52,14 @@ std::string CollapseSlashes(const std::string & path)
     return result;
 }
 
-static struct ExitManager
-{
-    std::string exitCommand;
-    bool runExitCommand = true;
-    ~ExitManager()
-    {
-        if(runExitCommand)
-            system(exitCommand.c_str());
-    }
-} _exitManager;
+static ApplicationLifecycle lifecycle;
 
 int main(int argc, char * argv[])
 {
     std::string optionsLocation(argv[0]);
     optionsLocation = CollapseSlashes(optionsLocation.substr(0, optionsLocation.find_last_of('/')+1));
-    _exitManager.exitCommand = "/bin/sh " + optionsLocation + "/scripts/ResumeUI.sh";
+    lifecycle.SetResumeScript(optionsLocation + "/scripts/ResumeUI.sh");
+    lifecycle.InstallSignalHandlers();
     std::string commandLocation(optionsLocation + "commands/");
     std::string scriptLocation(optionsLocation + "scripts/");
 
@@ -113,12 +107,9 @@ int main(int argc, char * argv[])
     commandLocation = CollapseSlashes(commandLocation);
     scriptLocation = CollapseSlashes(scriptLocation);
 
-    std::string myEntry = commandLocation + "," + scriptLocation + "," + titleKey + (selectedMarker.empty() ? "" : "," + selectedMarker);
-    size_t lastSep = backStack.find_last_of(';');
-    std::string lastEntry = backStack.empty() ? "" : (lastSep == std::string::npos ? backStack : backStack.substr(lastSep + 1));
-    if(lastEntry == myEntry)
-        backStack = (lastSep == std::string::npos) ? "" : backStack.substr(0, lastSep);
-    setenv("OM_BACK_STACK", (backStack.empty() ? myEntry : backStack + ";" + myEntry).c_str(), 1);
+    const std::string myEntry = back_stack::MakeEntry(commandLocation, scriptLocation, titleKey, selectedMarker);
+    backStack = back_stack::PopIfLast(backStack, myEntry);
+    setenv("OM_BACK_STACK", back_stack::Push(backStack, myEntry).c_str(), 1);
 
     auto ExpandTemplates = [&](std::string & cmd)
     {
@@ -171,51 +162,18 @@ int main(int argc, char * argv[])
     else
     {
         std::cerr << "Cannot open input folder.\n";
+        lifecycle.Decide(ExitAction::Resume);
         exit(1);
     }
 
     if(commands.empty())
     {
         std::cerr << "No usable commands in " << commandLocation << "\n";
+        lifecycle.Decide(ExitAction::Resume);
         exit(1);
     }
 
-    std::string backCommand;
-    if(!backStack.empty())
-    {
-        std::vector<std::string> entries;
-        for(size_t start = 0; start < backStack.size();)
-        {
-            size_t sep = backStack.find(';', start);
-            if(sep == std::string::npos) sep = backStack.size();
-            entries.push_back(backStack.substr(start, sep-start));
-            start = sep+1;
-        }
-        std::string lastEntry = entries.back();
-        entries.pop_back();
-        std::string remainingStack;
-        for(size_t i = 0; i < entries.size(); ++i)
-        {
-            if(i) remainingStack += ";";
-            remainingStack += entries[i];
-        }
-
-        const size_t c1 = lastEntry.find(',');
-        const size_t c2 = c1 == std::string::npos ? c1 : lastEntry.find(',', c1+1);
-        if(c2 != std::string::npos)
-        {
-            std::string backPath = lastEntry.substr(0, c1);
-            std::string backScriptPath = lastEntry.substr(c1+1, c2-c1-1);
-            const size_t c3 = lastEntry.find(',', c2+1);
-            std::string backTitleKey = lastEntry.substr(c2+1, c3 == std::string::npos ? std::string::npos : c3-c2-1);
-            std::string backMarker = c3 == std::string::npos ? "" : lastEntry.substr(c3+1);
-
-            backCommand = "usleep 50000 && OM_BACK_STACK=\"" + remainingStack + "\" " + optionsLocation + "options --commandPath " + backPath
-                + (backScriptPath.empty() ? "" : " --scriptPath " + backScriptPath)
-                + " --title \"" + backTitleKey + "\""
-                + (backMarker.empty() ? "" : " --selectedMarker \"" + backMarker + "\"") + " &";
-        }
-    }
+    const std::string backCommand = back_stack::BackCommand(backStack, optionsLocation);
 
     int currentCommandId = 0;
 
@@ -541,8 +499,8 @@ int main(int argc, char * argv[])
         const std::string & confirmKey = commands[currentCommandId].deleteConfirmKey;
         if(!Confirm(Translate(confirmKey.empty() ? "DELETE_CONFIRM_GENERIC" : confirmKey)))
             return false;
+        lifecycle.Decide(ExitAction::Leave);
         system(commands[currentCommandId].deleteCommand.c_str());
-        _exitManager.runExitCommand = false;
         return true;
     };
 
@@ -557,12 +515,14 @@ int main(int argc, char * argv[])
         SDL_Event e;
         while (SDL_PollEvent(&e)) {
             if (e.type == SDL_QUIT) {
+                lifecycle.Decide(ExitAction::Resume);
                 return 0;
             }
         }
 
         if(sdl_context.powerwatch->buttonPress())
         {
+            lifecycle.Decide(ExitAction::Resume);
             break;
         }
         if(controller.GetButtonStatus(A) || controller.GetButtonStatus(START))
@@ -586,8 +546,8 @@ int main(int argc, char * argv[])
             }
             else if(confirmed)
             {
+                lifecycle.Decide(commands[currentCommandId].restartUI ? ExitAction::Resume : ExitAction::Leave);
                 system(commands[currentCommandId].command.c_str());
-                _exitManager.runExitCommand = commands[currentCommandId].restartUI;
                 break;
             }
         }
@@ -614,9 +574,9 @@ int main(int argc, char * argv[])
         {
             if(bWasHeld && !bHoldFired)
             {
+                lifecycle.Decide(backCommand.empty() ? ExitAction::Resume : ExitAction::Leave);
                 if(!backCommand.empty())
                     system(backCommand.c_str());
-                _exitManager.runExitCommand = backCommand.empty();
                 break;
             }
             bHoldFired = false;