Added an application updater that checks for new releases on startup.

CMakeLists.txt

@@ -32,20 +32,22 @@ list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/CMake/Utils
                               ${CMAKE_CURRENT_SOURCE_DIR}/CMake/Packages)
 
 # Define the options.
-option(GL "Set to ON if targeting Desktop OpenGL" ${GL})
+option(GL "Set to ON if targeting Desktop OpenGL" ON)
-option(GLES "Set to ON if targeting OpenGL ES" ${GLES})
+option(GLES "Set to ON if targeting OpenGL ES" OFF)
-option(APPIMAGE_BUILD "Set to ON when building as an AppImage" ${APPIMAGE_BUILD})
+option(APPLICATION_UPDATER "Set to OFF to build without the application updater" ON)
-option(FLATPAK_BUILD "Set to ON when building as a Flatpak" ${FLATPAK_BUILD})
+option(APPIMAGE_BUILD "Set to ON when building as an AppImage" OFF)
-option(STEAM_DECK "Set to ON to enable a Valve Steam Deck specific build" ${STEAM_DECK})
+option(AUR_BUILD "Set to ON when building for the AUR" OFF)
-option(RETRODECK "Set to ON to enable a RetroDECK specific build" ${RETRODECK})
+option(FLATPAK_BUILD "Set to ON when building as a Flatpak" OFF)
-option(RPI "Set to ON to enable a Raspberry Pi specific build" ${RPI})
+option(STEAM_DECK "Set to ON to enable a Valve Steam Deck specific build" OFF)
-option(BUNDLED_CERTS "Set to ON to use bundled TLS/SSL certificates" ${BUNDLED_CERTS})
+option(RETRODECK "Set to ON to enable a RetroDECK specific build" OFF)
-option(CEC "Set to ON to enable CEC" ${CEC})
+option(RPI "Set to ON to enable a Raspberry Pi specific build" OFF)
-option(VIDEO_HW_DECODING "Set to ON to enable FFmpeg HW decoding" ${VIDEO_HW_DECODING})
+option(BUNDLED_CERTS "Set to ON to use bundled TLS/SSL certificates" OFF)
-option(CLANG_TIDY "Set to ON to build using the clang-tidy static analyzer" ${CLANG_TIDY})
+option(CEC "Set to ON to enable CEC" OFF)
-option(ASAN "Set to ON to build with AddressSanitizer" ${ASAN})
+option(VIDEO_HW_DECODING "Set to ON to enable FFmpeg HW decoding" OFF)
-option(TSAN "Set to ON to build with ThreadSanitizer" ${TSAN})
+option(CLANG_TIDY "Set to ON to build using the clang-tidy static analyzer" OFF)
-option(UBSAN "Set to ON to build with UndefinedBehaviorSanitizer" ${UBSAN})
+option(ASAN "Set to ON to build with AddressSanitizer" OFF)
+option(TSAN "Set to ON to build with ThreadSanitizer" OFF)
+option(UBSAN "Set to ON to build with UndefinedBehaviorSanitizer" OFF)
 
 if(CLANG_TIDY)
     find_program(CLANG_TIDY_BINARY NAMES clang-tidy)
@@ -287,7 +289,7 @@ if(GLES)
     message("-- Building with OpenGL ES renderer")
 endif()
 
-if (APPIMAGE_BUILD AND FLATPAK_BUILD)
+if(APPIMAGE_BUILD AND FLATPAK_BUILD)
     message(FATAL_ERROR "-- APPIMAGE_BUILD and FLATPAK_BUILD can't be combined")
 endif()
 
@@ -307,6 +309,10 @@ if(FLATPAK_BUILD)
     message("-- Building as a Flatpak")
 endif()
 
+if(AUR_BUILD)
+    message("-- Building for the AUR")
+endif()
+
 if(STEAM_DECK AND RETRODECK)
     message(FATAL_ERROR "-- STEAM_DECK and RETRODECK can't be combined")
 endif()
@@ -339,13 +345,44 @@ if(VIDEO_HW_DECODING)
     message("-- Building with FFmpeg HW decoding")
 endif()
 
+if(AUR_BUILD OR FLATPAK_BUILD OR RETRODECK OR RPI)
+    set(APPLICATION_UPDATER OFF)
+endif()
+
+if(CMAKE_SYSTEM_NAME MATCHES FreeBSD OR CMAKE_SYSTEM_NAME MATCHES NetBSD OR CMAKE_SYSTEM_NAME MATCHES OpenBSD)
+    set(APPLICATION_UPDATER OFF)
+endif()
+
+if(APPLICATION_UPDATER)
+    add_compile_definitions(APPLICATION_UPDATER)
+else()
+    message("-- Building without application updater")
+endif()
+
+# This is needed to identify the package type for the application updater.
+if(CMAKE_SYSTEM_NAME MATCHES Linux)
+    if(LINUX_CPACK_GENERATOR MATCHES DEB)
+        add_compile_definitions(LINUX_DEB_PACKAGE)
+    elseif(LINUX_CPACK_GENERATOR MATCHES RPM)
+        add_compile_definitions(LINUX_RPM_PACKAGE)
+    endif()
+endif()
+
+if(APPLE)
+    if(CMAKE_SYSTEM_PROCESSOR MATCHES arm)
+        add_compile_definitions(MACOS_APPLE_CPU)
+    else()
+        add_compile_definitions(MACOS_INTEL_CPU)
+    endif()
+endif()
+
 if(APPLE AND CMAKE_OSX_DEPLOYMENT_TARGET VERSION_LESS 10.14)
     add_compile_definitions(LEGACY_MACOS)
 endif()
 
-# If it's an alpha, beta or dev build, then display the build date in the main menu.
+# Affects the application updater and is used for displaying version info in the main menu.
 if(ES_VERSION MATCHES alpha OR ES_VERSION MATCHES beta OR ES_VERSION MATCHES dev)
-    add_compile_definitions(MENU_BUILD_DATE)
+    add_compile_definitions(IS_PRERELEASE)
 endif()
 
 # GLM library options.

es-app/CMakeLists.txt

@@ -10,6 +10,7 @@
 project(emulationstation-de)
 
 set(ES_HEADERS
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/ApplicationUpdater.h
     ${CMAKE_CURRENT_SOURCE_DIR}/src/CollectionSystemsManager.h
     ${CMAKE_CURRENT_SOURCE_DIR}/src/EmulationStation.h
     ${CMAKE_CURRENT_SOURCE_DIR}/src/FileData.h
@@ -58,6 +59,7 @@ set(ES_HEADERS
 )
 
 set(ES_SOURCES
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/ApplicationUpdater.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/CollectionSystemsManager.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/FileData.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/FileFilterIndex.cpp

es-app/src/ApplicationUpdater.cpp

@@ -0,0 +1,403 @@
+//  SPDX-License-Identifier: MIT
+//
+//  EmulationStation Desktop Edition
+//  ApplicationUpdater.cpp
+//
+//  Checks for application updates.
+//  In the future updates will also be downloaded and possibly installed.
+//
+
+#include "ApplicationUpdater.h"
+
+#include "EmulationStation.h"
+#include "Log.h"
+#include "Settings.h"
+#include "utils/StringUtil.h"
+#include "utils/TimeUtil.h"
+
+#include "rapidjson/document.h"
+#include "rapidjson/error/en.h"
+
+#include <SDL2/SDL_timer.h>
+
+#include <algorithm>
+#include <deque>
+
+#define MAX_DOWNLOAD_TIME 1
+
+ApplicationUpdater::ApplicationUpdater()
+    : mTimer {0}
+    , mMaxTime {0}
+    , mAbortDownload {false}
+    , mCheckedForUpdate {false}
+{
+    mUrl = "https://gitlab.com/api/v4/projects/18817634/repository/files/latest_release.json/"
+           "raw?ref=master";
+}
+
+ApplicationUpdater::~ApplicationUpdater()
+{
+    // This is needed if getResults() was never called.
+    if (mThread)
+        mThread->join();
+}
+
+void ApplicationUpdater::checkForUpdates()
+{
+    const std::string updateFrequency {
+        Settings::getInstance()->getString("ApplicationUpdaterFrequency")};
+    if (updateFrequency == "never")
+        return;
+
+    const std::string lastCheck {Settings::getInstance()->getString("ApplicationUpdaterLastCheck")};
+    unsigned int frequencyDays {0};
+    bool checkForUpdate {false};
+
+    if (updateFrequency == "daily")
+        frequencyDays = 1;
+    else if (updateFrequency == "weekly")
+        frequencyDays = 7;
+    else if (updateFrequency == "monthly")
+        frequencyDays = 30;
+
+    // Frequency set to "always" or it's the first time we check for updates.
+    if (frequencyDays == 0 || lastCheck == "") {
+        checkForUpdate = true;
+    }
+    else {
+        const Utils::Time::DateTime now {Utils::Time::now()};
+        const Utils::Time::DateTime lastTime {lastCheck};
+        const Utils::Time::Duration dur {now.getTime() - lastTime.getTime()};
+        if (dur.getDays() >= frequencyDays)
+            checkForUpdate = true;
+    }
+
+    if (checkForUpdate) {
+        LOG(LogInfo) << "Checking for application updates...";
+        mThread = std::make_unique<std::thread>(&ApplicationUpdater::updaterThread, this);
+    }
+}
+
+void ApplicationUpdater::updaterThread()
+{
+    if (!downloadFile()) {
+        compareVersions();
+    }
+}
+
+bool ApplicationUpdater::downloadFile()
+{
+    const unsigned int startTime {SDL_GetTicks()};
+    mTimer = startTime;
+    mMaxTime = mTimer + (MAX_DOWNLOAD_TIME * 1000);
+
+    mStatus = ASYNC_IN_PROGRESS;
+    mRequest = std::unique_ptr<HttpReq>(std::make_unique<HttpReq>(mUrl));
+
+    while (mTimer < mMaxTime || !mAbortDownload) {
+        SDL_Delay(10);
+        try {
+            update();
+        }
+        catch (std::runtime_error& e) {
+            LOG(LogWarning) << "ApplicationUpdater: Couldn't download \"latest_release.json\": "
+                            << e.what();
+            return true;
+        }
+        if (mStatus == ASYNC_DONE)
+            break;
+        mTimer = SDL_GetTicks();
+    };
+
+    if (mStatus == ASYNC_DONE) {
+        rapidjson::Document doc;
+        const std::string& fileContents {mRequest->getContent()};
+        doc.Parse(&fileContents[0], fileContents.length());
+        if (doc.HasMember("error") && doc["error"].IsString()) {
+            LOG(LogWarning)
+                << "ApplicationUpdater: Couldn't download \"latest_release.json\", received "
+                   "server error response \""
+                << doc["error"].GetString() << "\"";
+            return true;
+        }
+        LOG(LogDebug)
+            << "ApplicationUpdater::downloadFile(): Downloaded \"latest_release.json\" in "
+            << mTimer - startTime << " milliseconds";
+        try {
+            parseFile();
+        }
+        catch (std::runtime_error& e) {
+            LOG(LogError) << "ApplicationUpdater: Couldn't parse \"latest_release.json\": "
+                          << e.what();
+            return true;
+        }
+    }
+    else if (mAbortDownload) {
+        LOG(LogWarning) << "ApplicationUpdater: Aborted download of \"latest_release.json\" after "
+                        << mTimer - startTime << " milliseconds as the application has started up";
+        return true;
+    }
+    else {
+        LOG(LogWarning) << "ApplicationUpdater: Couldn't download \"latest_release.json\" within "
+                        << MAX_DOWNLOAD_TIME << " second time limit";
+        return true;
+    }
+
+    return false;
+}
+
+void ApplicationUpdater::update()
+{
+    HttpReq::Status reqStatus {mRequest->status()};
+    if (reqStatus == HttpReq::REQ_SUCCESS) {
+        mStatus = ASYNC_DONE;
+        return;
+    }
+
+    // Not ready yet.
+    if (reqStatus == HttpReq::REQ_IN_PROGRESS)
+        return;
+
+    // Everything else is some sort of error.
+    std::string errorMessage {"Network error (status: "};
+    errorMessage.append(std::to_string(reqStatus)).append(") - ").append(mRequest->getErrorMsg());
+    throw std::runtime_error(errorMessage);
+}
+
+void ApplicationUpdater::parseFile()
+{
+    assert(mRequest->status() == HttpReq::REQ_SUCCESS);
+
+    const std::string fileContents {mRequest->getContent()};
+    rapidjson::Document doc;
+    doc.Parse(&fileContents[0], fileContents.length());
+
+    if (doc.HasParseError())
+        throw std::runtime_error(rapidjson::GetParseError_En(doc.GetParseError()));
+
+    const std::vector<std::string> releaseTypes {"stable", "prerelease"};
+
+    for (auto& releaseType : releaseTypes) {
+        Release release;
+        if (doc.HasMember(releaseType.c_str())) {
+            release.releaseType = releaseType.c_str();
+            const rapidjson::Value& releaseTypeEntry {doc[releaseType.c_str()]};
+
+            if (releaseTypeEntry.HasMember("version") && releaseTypeEntry["version"].IsString())
+                release.version = releaseTypeEntry["version"].GetString();
+            else
+                throw std::runtime_error("Invalid file structure, \"version\" key missing");
+
+            // There may not be a prerelease available.
+            if (releaseType == "prerelease" && release.version == "")
+                continue;
+
+            if (releaseTypeEntry.HasMember("release") && releaseTypeEntry["release"].IsString())
+                release.releaseNum = releaseTypeEntry["release"].GetString();
+            else
+                throw std::runtime_error("Invalid file structure, \"release\" key missing");
+
+            if (releaseTypeEntry.HasMember("date") && releaseTypeEntry["date"].IsString())
+                release.date = releaseTypeEntry["date"].GetString();
+            else
+                throw std::runtime_error("Invalid file structure, \"date\" key missing");
+
+            if (releaseTypeEntry.HasMember("packages") && releaseTypeEntry["packages"].IsArray()) {
+                const rapidjson::Value& packages {releaseTypeEntry["packages"]};
+                for (int i {0}; i < static_cast<int>(packages.Size()); ++i) {
+                    Package package;
+                    const rapidjson::Value& packageEntry {packages[i]};
+
+                    if (packageEntry.HasMember("name") && packageEntry["name"].IsString())
+                        package.name = packageEntry["name"].GetString();
+                    else
+                        throw std::runtime_error(
+                            "Invalid file structure, package \"name\" key missing");
+
+                    if (packageEntry.HasMember("filename") && packageEntry["filename"].IsString())
+                        package.filename = packageEntry["filename"].GetString();
+                    else
+                        throw std::runtime_error(
+                            "Invalid file structure, package \"filename\" key missing");
+
+                    if (packageEntry.HasMember("url") && packageEntry["url"].IsString())
+                        package.url = packageEntry["url"].GetString();
+                    else
+                        throw std::runtime_error(
+                            "Invalid file structure, package \"url\" key missing");
+
+                    if (packageEntry.HasMember("md5") && packageEntry["md5"].IsString())
+                        package.md5 = packageEntry["md5"].GetString();
+                    else
+                        throw std::runtime_error(
+                            "Invalid file structure, package \"md5\" key missing");
+
+                    if (packageEntry.HasMember("message") && packageEntry["message"].IsString())
+                        package.message = packageEntry["message"].GetString();
+                    else
+                        throw std::runtime_error(
+                            "Invalid file structure, package \"message\" key missing");
+
+                    release.packages.emplace_back(package);
+                }
+            }
+            else {
+                throw std::runtime_error("Invalid file structure");
+            }
+            if (releaseType == "stable")
+                mStableRelease = std::move(release);
+            else
+                mPrerelease = std::move(release);
+        }
+        else {
+            throw std::runtime_error("Invalid file structure, release type \"" + releaseType +
+                                     "\" missing");
+        }
+    }
+    if (mPrerelease.version == "") {
+        LOG(LogDebug) << "ApplicationUpdater::parseFile(): Latest stable release is "
+                      << mStableRelease.version << " (r" << mStableRelease.releaseNum
+                      << "), no prerelease currently available";
+    }
+    else {
+        LOG(LogDebug) << "ApplicationUpdater::parseFile(): Latest stable release is "
+                      << mStableRelease.version << " (r" << mStableRelease.releaseNum
+                      << ") and latest prerelease is " << mPrerelease.version << " (r"
+                      << mPrerelease.releaseNum << ")";
+    }
+}
+
+void ApplicationUpdater::compareVersions()
+{
+    std::deque<Release*> releaseTypes {&mStableRelease};
+
+    if (mPrerelease.version != "") {
+#if defined(IS_PRERELEASE)
+        releaseTypes.emplace_front(&mPrerelease);
+#else
+        if (Settings::getInstance()->getBool("ApplicationUpdaterPrereleases"))
+            releaseTypes.emplace_front(&mPrerelease);
+#endif
+    }
+
+    for (auto& releaseType : releaseTypes) {
+        bool newVersion {false};
+        // If the version does not follow the semantic versioning scheme then always consider it to
+        // be a new release as perhaps the version scheme will be changed sometime in the future.
+        if (count_if(releaseType->version.cbegin(), releaseType->version.cend(),
+                     [](char c) { return c == '.'; }) != 2) {
+            newVersion = true;
+        }
+        else {
+            std::vector<std::string> fileVersion {
+                Utils::String::delimitedStringToVector(releaseType->version, ".")};
+
+            const size_t dashPos {fileVersion.back().find('-')};
+            if (dashPos != std::string::npos)
+                fileVersion.back() = fileVersion.back().substr(0, dashPos);
+
+            int versionWeight {0};
+
+            if (std::stoi(fileVersion.at(0)) > PROGRAM_VERSION_MAJOR)
+                versionWeight += 8;
+            else if (std::stoi(fileVersion.at(0)) < PROGRAM_VERSION_MAJOR)
+                versionWeight -= 8;
+
+            if (std::stoi(fileVersion.at(1)) > PROGRAM_VERSION_MINOR)
+                versionWeight += 4;
+            else if (std::stoi(fileVersion.at(1)) < PROGRAM_VERSION_MINOR)
+                versionWeight -= 4;
+
+            if (std::stoi(fileVersion.at(2)) > PROGRAM_VERSION_MAINTENANCE)
+                versionWeight += 2;
+            else if (std::stoi(fileVersion.at(2)) < PROGRAM_VERSION_MAINTENANCE)
+                versionWeight -= 2;
+
+            // If versions match precisely then fall back to using the release number.
+            if (versionWeight == 0 && std::stoi(releaseType->releaseNum) > PROGRAM_RELEASE_NUMBER)
+                ++versionWeight;
+
+            if (versionWeight > 0)
+                newVersion = true;
+        }
+        if (newVersion) {
+            std::string message;
+
+            for (auto& package : releaseType->packages) {
+#if defined(_WIN64)
+                if (Settings::getInstance()->getBool("PortableMode")) {
+                    if (package.name == "WindowsPortable")
+                        message = package.message;
+                }
+                else {
+                    if (package.name == "WindowsInstaller")
+                        message = package.message;
+                }
+#elif defined(MACOS_APPLE_CPU)
+                if (package.name == "macOSApple")
+                    message = package.message;
+#elif defined(MACOS_INTEL_CPU)
+                if (package.name == "macOSIntel")
+                    message = package.message;
+#elif defined(STEAM_DECK)
+                if (package.name == "LinuxSteamDeckAppImage")
+                    message = package.message;
+#elif defined(APPIMAGE_BUILD)
+                if (package.name == "LinuxAppImage")
+                    message = package.message;
+#elif defined(LINUX_DEB_PACKAGE)
+                if (package.name == "LinuxDEB")
+                    message = package.message;
+#elif defined(LINUX_RPM_PACKAGE)
+                if (package.name == "LinuxRPM")
+                    message = package.message;
+#endif
+                auto tempVar = package;
+            }
+
+            // Cut the message to 280 characters so we don't make the message box exceedingly large.
+            message = message.substr(0, 280);
+
+            LOG(LogInfo) << "ApplicationUpdater: A new "
+                         << (releaseType == &mStableRelease ? "stable release" : "prerelease")
+                         << " is available for download at https://es-de.org: "
+                         << releaseType->version << " (r" << releaseType->releaseNum
+                         << "), release date: " << releaseType->date;
+
+            mResults.append("New ")
+                .append(releaseType == &mStableRelease ? "release " : "prerelease ")
+                .append("available!\n")
+                .append(releaseType->version)
+                .append(" (")
+                .append(releaseType->date)
+                .append(")\n")
+                .append("can now be downloaded from\n")
+                .append("https://es-de.org/");
+
+            if (message != "")
+                mResults.append("\n").append(message);
+
+            mResults = Utils::String::toUpper(mResults);
+            break;
+        }
+    }
+    mCheckedForUpdate = true;
+}
+
+void ApplicationUpdater::getResults(std::string& results)
+{
+    mAbortDownload = true;
+
+    if (mThread) {
+        mThread->join();
+        mThread.reset();
+        if (mCheckedForUpdate) {
+            if (mResults != "")
+                results = mResults;
+            Settings::getInstance()->setString(
+                "ApplicationUpdaterLastCheck",
+                Utils::Time::DateTime(Utils::Time::now()).getIsoString());
+            Settings::getInstance()->saveFile();
+        }
+    }
+}

es-app/src/ApplicationUpdater.h

@@ -0,0 +1,67 @@
+//  SPDX-License-Identifier: MIT
+//
+//  EmulationStation Desktop Edition
+//  ApplicationUpdater.h
+//
+//  Checks for application updates.
+//  In the future updates will also be downloaded and possibly installed.
+//
+
+#ifndef ES_APP_APPLICATION_UPDATER_H
+#define ES_APP_APPLICATION_UPDATER_H
+
+#include "AsyncHandle.h"
+#include "HttpReq.h"
+
+#include <atomic>
+#include <memory>
+#include <thread>
+#include <vector>
+
+class ApplicationUpdater : public AsyncHandle
+{
+public:
+    ApplicationUpdater();
+    ~ApplicationUpdater();
+
+    void checkForUpdates();
+    void updaterThread();
+    bool downloadFile();
+    void update() override;
+    void parseFile();
+    void compareVersions();
+    void getResults(std::string& results);
+
+private:
+    struct Package {
+        std::string name;
+        std::string filename;
+        std::string url;
+        std::string md5;
+        std::string message;
+    };
+
+    struct Release {
+        std::string releaseType;
+        std::string version;
+        std::string releaseNum;
+        std::string date;
+        std::vector<Package> packages;
+    };
+
+    std::string mUrl;
+    std::string mResults;
+    unsigned int mTimer;
+    unsigned int mMaxTime;
+    std::atomic<bool> mAbortDownload;
+    bool mCheckedForUpdate;
+
+    std::unique_ptr<std::thread> mThread;
+    std::unique_ptr<HttpReq> mRequest;
+    AsyncHandleStatus mStatus;
+
+    Release mStableRelease;
+    Release mPrerelease;
+};
+
+#endif // ES_APP_APPLICATION_UPDATER_H

es-app/src/guis/GuiMenu.cpp

@@ -1408,6 +1408,48 @@ void GuiMenu::openOtherOptions()
         }
     });
 
+#if defined(APPLICATION_UPDATER)
+    // Application updater frequency.
+    auto applicationUpdaterFrequency = std::make_shared<OptionListComponent<std::string>>(
+        getHelpStyle(), "APPLICATION UPDATES", false);
+    const std::string& selectedUpdaterFrequency {
+        Settings::getInstance()->getString("ApplicationUpdaterFrequency")};
+    applicationUpdaterFrequency->add("ALWAYS", "always", selectedUpdaterFrequency == "always");
+    applicationUpdaterFrequency->add("DAILY", "daily", selectedUpdaterFrequency == "daily");
+    applicationUpdaterFrequency->add("WEEKLY", "weekly", selectedUpdaterFrequency == "weekly");
+    applicationUpdaterFrequency->add("MONTHLY", "monthly", selectedUpdaterFrequency == "monthly");
+    applicationUpdaterFrequency->add("NEVER", "never", selectedUpdaterFrequency == "never");
+    // If there are no objects returned, then there must be a manually modified entry in the
+    // configuration file. Simply set updater frequency to "always" in this case.
+    if (applicationUpdaterFrequency->getSelectedObjects().size() == 0)
+        applicationUpdaterFrequency->selectEntry(0);
+    s->addWithLabel("CHECK FOR APPLICATION UPDATES", applicationUpdaterFrequency);
+    s->addSaveFunc([applicationUpdaterFrequency, s] {
+        if (applicationUpdaterFrequency->getSelected() !=
+            Settings::getInstance()->getString("ApplicationUpdaterFrequency")) {
+            Settings::getInstance()->setString("ApplicationUpdaterFrequency",
+                                               applicationUpdaterFrequency->getSelected());
+            s->setNeedsSaving();
+        }
+    });
+#endif
+
+#if defined(APPLICATION_UPDATER) && !defined(IS_PRERELEASE)
+    // Whether to include prereleases when checking for application updates.
+    auto applicationUpdaterPrereleases = std::make_shared<SwitchComponent>();
+    applicationUpdaterPrereleases->setState(
+        Settings::getInstance()->getBool("ApplicationUpdaterPrereleases"));
+    s->addWithLabel("INCLUDE PRERELEASES IN UPDATE CHECKS", applicationUpdaterPrereleases);
+    s->addSaveFunc([applicationUpdaterPrereleases, s] {
+        if (applicationUpdaterPrereleases->getState() !=
+            Settings::getInstance()->getBool("ApplicationUpdaterPrereleases")) {
+            Settings::getInstance()->setBool("ApplicationUpdaterPrereleases",
+                                             applicationUpdaterPrereleases->getState());
+            s->setNeedsSaving();
+        }
+    });
+#endif
+
 #if defined(_WIN64)
     // Hide taskbar during the program session.
     auto hide_taskbar = std::make_shared<SwitchComponent>();
@@ -1591,6 +1633,29 @@ void GuiMenu::openOtherOptions()
     });
 #endif
 
+#if defined(APPLICATION_UPDATER) && !defined(IS_PRERELEASE)
+    auto applicationUpdaterFrequencyFunc = [applicationUpdaterFrequency,
+                                            applicationUpdaterPrereleases](const std::string&) {
+        if (applicationUpdaterFrequency->getSelected() == "never") {
+            applicationUpdaterPrereleases->setEnabled(false);
+            applicationUpdaterPrereleases->setOpacity(DISABLED_OPACITY);
+            applicationUpdaterPrereleases->getParent()
+                ->getChild(applicationUpdaterPrereleases->getChildIndex() - 1)
+                ->setOpacity(DISABLED_OPACITY);
+        }
+        else {
+            applicationUpdaterPrereleases->setEnabled(true);
+            applicationUpdaterPrereleases->setOpacity(1.0f);
+            applicationUpdaterPrereleases->getParent()
+                ->getChild(applicationUpdaterPrereleases->getChildIndex() - 1)
+                ->setOpacity(1.0f);
+        }
+    };
+
+    applicationUpdaterFrequencyFunc(std::string());
+    applicationUpdaterFrequency->setCallback(applicationUpdaterFrequencyFunc);
+#endif
+
     s->setSize(mSize);
     mWindow->pushGui(s);
 }
@@ -1673,7 +1738,7 @@ void GuiMenu::addVersionInfo()
     mVersion.setFont(Font::get(FONT_SIZE_SMALL));
     mVersion.setColor(0x5E5E5EFF);
 
-#if defined(MENU_BUILD_DATE)
+#if defined(IS_PRERELEASE)
     mVersion.setText("EMULATIONSTATION-DE  V" + Utils::String::toUpper(PROGRAM_VERSION_STRING) +
                      " (Built " + __DATE__ + ")");
 #else

es-app/src/main.cpp

@@ -17,6 +17,7 @@
 //  environment and starts listening to SDL events.
 //
 
+#include "ApplicationUpdater.h"
 #include "AudioManager.h"
 #include "CollectionSystemsManager.h"
 #include "EmulationStation.h"
@@ -62,6 +63,9 @@ namespace
     Window* window {nullptr};
     int lastTime {0};
 
+#if defined(APPLICATION_UPDATER)
+    bool noUpdateCheck {false};
+#endif
     bool forceInputConfig {false};
     bool createSystemDirectories {false};
     bool settingsNeedSaving {false};
@@ -361,6 +365,11 @@ bool parseArgs(int argc, char* argv[])
         else if (strcmp(argv[i], "--no-splash") == 0) {
             Settings::getInstance()->setBool("SplashScreen", false);
         }
+#if defined(APPLICATION_UPDATER)
+        else if (strcmp(argv[i], "--no-update-check") == 0) {
+            noUpdateCheck = true;
+        }
+#endif
         else if (strcmp(argv[i], "--gamelist-only") == 0) {
             Settings::getInstance()->setBool("ParseGamelistOnly", true);
             settingsNeedSaving = true;
@@ -418,6 +427,9 @@ bool parseArgs(int argc, char* argv[])
 "  --anti-aliasing [0, 2 or 4]           Set MSAA anti-aliasing to disabled, 2x or 4x\n"
 #endif
 "  --no-splash                           Don't show the splash screen during startup\n"
+#if defined(APPLICATION_UPDATER)
+"  --no-update-check                     Don't check for application updates during startup\n"
+#endif
 "  --gamelist-only                       Skip automatic game ROM search, only read from gamelist.xml\n"
 "  --ignore-gamelist                     Ignore the gamelist.xml files\n"
 "  --show-hidden-files                   Show hidden files and folders\n"
@@ -587,6 +599,10 @@ int main(int argc, char* argv[])
                  << PROGRAM_RELEASE_NUMBER << "), built " << PROGRAM_BUILT_STRING;
     if (portableMode) {
         LOG(LogInfo) << "Running in portable mode";
+        Settings::getInstance()->setBool("PortableMode", true);
+    }
+    else {
+        Settings::getInstance()->setBool("PortableMode", false);
     }
 
     // Always close the log on exit.
@@ -676,6 +692,15 @@ int main(int argc, char* argv[])
 
     renderer = Renderer::getInstance();
     window = Window::getInstance();
+
+#if defined(APPLICATION_UPDATER)
+    std::unique_ptr<ApplicationUpdater> applicationUpdater;
+    if (!noUpdateCheck) {
+        applicationUpdater = std::make_unique<ApplicationUpdater>();
+        applicationUpdater->checkForUpdates();
+    }
+#endif
+
     ViewController::getInstance();
     CollectionSystemsManager::getInstance();
     Screensaver screensaver;
@@ -743,9 +768,14 @@ int main(int argc, char* argv[])
     }
 
     if (!SystemData::sStartupExitSignal) {
-        if (loadSystemsStatus == loadSystemsReturnCode::LOADING_OK)
+        std::string updaterResults;
+        if (loadSystemsStatus == loadSystemsReturnCode::LOADING_OK) {
             ThemeData::themeLoadedLogOutput();
-
+#if defined(APPLICATION_UPDATER)
+            if (!noUpdateCheck)
+                applicationUpdater->getResults(updaterResults);
+#endif
+        }
         // Open the input configuration GUI if the force flag was passed from the command line.
         if (!loadSystemsStatus) {
             if (forceInputConfig) {
@@ -762,12 +792,22 @@ int main(int argc, char* argv[])
 
         lastTime = SDL_GetTicks();
 
+#if defined(APPLICATION_UPDATER)
+        if (!noUpdateCheck)
+            applicationUpdater.reset();
+#endif
+
         LOG(LogInfo) << "Application startup time: "
                      << std::chrono::duration_cast<std::chrono::milliseconds>(
                             std::chrono::system_clock::now() - applicationStartTime)
                             .count()
                      << " ms";
 
+#if defined(APPLICATION_UPDATER)
+        if (updaterResults != "")
+            ViewController::getInstance()->updateAvailableDialog(updaterResults);
+#endif
+
         // Main application loop.
 
         if (!SystemData::sStartupExitSignal) {

es-app/src/views/ViewController.cpp

@@ -208,6 +208,15 @@ void ViewController::invalidAlternativeEmulatorDialog()
                                                    "INTERFACE IN THE 'OTHER SETTINGS' MENU"));
 }
 
+void ViewController::updateAvailableDialog(const std::string& message)
+{
+    mWindow->pushGui(new GuiMsgBox(getHelpStyle(), message, "OK", nullptr, "", nullptr, "", nullptr,
+                                   true, true,
+                                   (mRenderer->getIsVerticalOrientation() ?
+                                        0.85f :
+                                        0.45f * (1.778f / mRenderer->getScreenAspectRatio()))));
+}
+
 void ViewController::goToStart(bool playTransition)
 {
     // Needed to avoid segfaults during emergency shutdown.

es-app/src/views/ViewController.h

@@ -36,6 +36,7 @@ public:
     void invalidSystemsFileDialog();
     void noGamesDialog();
     void invalidAlternativeEmulatorDialog();
+    void updateAvailableDialog(const std::string& message);
 
     // Try to completely populate the GamelistView map.
     // Caches things so there's no pauses during transitions.

es-core/src/HttpReq.cpp

@@ -6,6 +6,7 @@
 //  HTTP request functions.
 //  Used by Scraper, GamesDBJSONScraper, GamesDBJSONScraperResources and
 //  ScreenScraper to download game information and media files.
+//  Also used by ApplicationUpdater to check for application updates.
 //
 
 #include "HttpReq.h"

es-core/src/HttpReq.h

@@ -6,6 +6,7 @@
 //  HTTP request functions.
 //  Used by Scraper, GamesDBJSONScraper, GamesDBJSONScraperResources and
 //  ScreenScraper to download game information and media files.
+//  Also used by ApplicationUpdater to check for application updates.
 //
 
 #ifndef ES_CORE_HTTP_REQ_H

es-core/src/Settings.cpp

@@ -5,6 +5,7 @@
 //
 //  Functions to read from and write to the configuration file es_settings.xml.
 //  The default values for the application settings are defined here as well.
+//  This class is not thread safe.
 //
 
 #include "Settings.h"
@@ -40,6 +41,7 @@ namespace
         "Debug",                // --debug
 
         // These options are only used internally during the application session:
+        "PortableMode",
         "DebugGrid",
         "DebugText",
         "DebugImage",
@@ -253,6 +255,8 @@ void Settings::setDefaults()
     mStringMap["KeyboardQuitShortcut"] = {"AltF4", "AltF4"};
 #endif
     mStringMap["SaveGamelistsMode"] = {"always", "always"};
+    mStringMap["ApplicationUpdaterFrequency"] = {"always", "always"};
+    mBoolMap["ApplicationUpdaterPrereleases"] = {false, false};
 #if defined(_WIN64)
     mBoolMap["HideTaskbar"] = {false, false};
 #endif
@@ -322,6 +326,8 @@ void Settings::setDefaults()
     //
 
     mStringMap["ApplicationVersion"] = {"", ""};
+    mStringMap["ApplicationUpdaterLastCheck"] = {"", ""};
+    mBoolMap["PortableMode"] = {false, false};
     mBoolMap["DebugGrid"] = {false, false};
     mBoolMap["DebugText"] = {false, false};
     mBoolMap["DebugImage"] = {false, false};

es-core/src/Settings.h

@@ -5,6 +5,7 @@
 //
 //  Functions to read from and write to the configuration file es_settings.xml.
 //  The default values for the application settings are defined here as well.
+//  This class is not thread safe.
 //
 
 #ifndef ES_CORE_SETTINGS_H