Add StateLocation & GenericStateLocation to StandardLocation

The latest XDG spec (0.8) defines XDG_STATE_HOME that does not exist
in QStandardPaths::StandardLocation.

Some Linux distributions clean XDG_CACHE_HOME on restart which makes
XDG_STATE_HOME useful as a path for saving application state.

This commit adds StateLocation and GenericStateLocation to serve as a
StandardLocation for XDG_STATE_HOME for all platforms.

This commit also updates docs and tests to fit the new changes.

[ChangeLog][QStandardPaths] Added StateLocation &
GenericStateLocation to StandardLocation

Change-Id: I470602466c37f085062cc64d15ea243711728fa5
Reviewed-by: David Faure <david.faure@kdab.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

10 files changed, 130 insertions, 8 deletions

diff --git a/doc/global/includes/standardpath/functiondocs.qdocinc b/doc/global/includes/standardpath/functiondocs.qdocinc
index c0f4763b90..5a008414c8 100644
--- a/doc/global/includes/standardpath/functiondocs.qdocinc
+++ b/doc/global/includes/standardpath/functiondocs.qdocinc
@@ -71,11 +71,13 @@
     It affects the locations into which test programs might write
     files: \c GenericDataLocation, \c AppDataLocation, \c ConfigLocation,
     \c GenericConfigLocation, \c AppConfigLocation,
+    \c StateLocation, \c GenericStateLocation,
     \c GenericCacheLocation, and \c CacheLocation. Other locations
     are not affected.
 
     On Unix, \c XDG_DATA_HOME is set to \c{~/.qttest/share},
-    \c XDG_CONFIG_HOME is set to \c{~/.qttest/config}, and
+    \c XDG_CONFIG_HOME is set to \c{~/.qttest/config},
+    \c XDG_STATE_HOME is set \c{~/.qttest/state} and
     \c XDG_CACHE_HOME is set to \c{~/.qttest/cache}.
 
     On macOS, data goes to \c{~/.qttest/Application Support},
diff --git a/src/corelib/io/qstandardpaths.cpp b/src/corelib/io/qstandardpaths.cpp
index 9a14ae0717..925a48dc94 100644
--- a/src/corelib/io/qstandardpaths.cpp
+++ b/src/corelib/io/qstandardpaths.cpp
@@ -126,6 +126,12 @@ using namespace Qt::StringLiterals;
            template files can be stored. This is a generic value. Note that the returned path may be
            empty if the system has no concept of a templates location.
            This enum value was added in Qt 6.4.
+    \value [since 6.7] StateLocation Returns a directory location where user-specific application
+           state data files should be written. This is an application-specific directory,
+           and the returned path is never empty.
+    \value [since 6.7] GenericStateLocation Returns a directory location where shared state data files
+           across applications should be written. This value might be generic or application-specific,
+           but the returned path is never empty.
 
     The following table gives examples of paths on different operating systems.
     The first path is the writable path (unless noted). Other, additional
@@ -166,6 +172,9 @@ using namespace Qt::StringLiterals;
     \row \li CacheLocation
          \li "~/Library/Caches/<APPNAME>", "/Library/Caches/<APPNAME>"
          \li "C:/Users/<USER>/AppData/Local/<APPNAME>/cache"
+    \row \li StateLocation
+         \li "~/Library/Preferences/<APPNAME>/State"
+         \li "C:/Users/<USER>/AppData/Local/<APPNAME>/State", "C:/ProgramData/<APPNAME>/State"
     \row \li GenericDataLocation
          \li "~/Library/Application Support", "/Library/Application Support"
          \li "C:/Users/<USER>/AppData/Local", "C:/ProgramData", "<APPDIR>", "<APPDIR>/data"
@@ -184,6 +193,9 @@ using namespace Qt::StringLiterals;
     \row \li GenericCacheLocation
          \li "~/Library/Caches", "/Library/Caches"
          \li "C:/Users/<USER>/AppData/Local/cache"
+    \row \li GenericStateLocation
+         \li "~/Library/Preferences/State"
+         \li "C:/Users/<USER>/AppData/Local/State", "C:/ProgramData/State"
     \row \li AppDataLocation
          \li "~/Library/Application Support/<APPNAME>", "/Library/Application Support/<APPNAME>". "<APPDIR>/../Resources"
          \li "C:/Users/<USER>/AppData/Roaming/<APPNAME>", "C:/ProgramData/<APPNAME>", "<APPDIR>", "<APPDIR>/data", "<APPDIR>/data/<APPNAME>"
@@ -222,6 +234,8 @@ using namespace Qt::StringLiterals;
          \li "~/.local/share/<APPNAME>", "/usr/local/share/<APPNAME>", "/usr/share/<APPNAME>"
     \row \li CacheLocation
          \li "~/.cache/<APPNAME>"
+    \row \li StateLocation
+         \li "~/.local/state/<APPNAME>"
     \row \li GenericDataLocation
          \li "~/.local/share", "/usr/local/share", "/usr/share"
     \row \li RuntimeLocation
@@ -234,6 +248,8 @@ using namespace Qt::StringLiterals;
          \li "~/Downloads"
     \row \li GenericCacheLocation
          \li "~/.cache"
+    \row \li GenericStateLocation
+         \li "~/.local/state"
     \row \li AppDataLocation
          \li "~/.local/share/<APPNAME>", "/usr/local/share/<APPNAME>", "/usr/share/<APPNAME>"
     \row \li AppConfigLocation
@@ -279,6 +295,10 @@ using namespace Qt::StringLiterals;
     \row \li CacheLocation
          \li "<APPROOT>/cache", "<USER>/<APPNAME>/cache"
          \li "<APPROOT>/Library/Caches"
+    \row \li StateLocation
+         \li "<APPROOT>/files/state"
+    \row \li GenericStateLocation (there is shared state)
+         \li "<APPROOT>/files/state"
     \row \li GenericDataLocation
          \li "<USER>" [*] or "<USER>/<APPNAME>/files"
          \li "<APPROOT>/Library/Application Support"
@@ -549,6 +569,8 @@ QString QStandardPaths::displayName(StandardLocation type)
         return QCoreApplication::translate("QStandardPaths", "Application Data");
     case CacheLocation:
         return QCoreApplication::translate("QStandardPaths", "Cache");
+    case StateLocation:
+        return QCoreApplication::translate("QStandardPaths", "State");
     case GenericDataLocation:
         return QCoreApplication::translate("QStandardPaths", "Shared Data");
     case RuntimeLocation:
@@ -559,6 +581,8 @@ QString QStandardPaths::displayName(StandardLocation type)
         return QCoreApplication::translate("QStandardPaths", "Shared Configuration");
     case GenericCacheLocation:
         return QCoreApplication::translate("QStandardPaths", "Shared Cache");
+    case GenericStateLocation:
+        return QCoreApplication::translate("QStandardPaths", "Shared State");
     case DownloadLocation:
         return QCoreApplication::translate("QStandardPaths", "Download");
     case AppDataLocation:
diff --git a/src/corelib/io/qstandardpaths.h b/src/corelib/io/qstandardpaths.h
index ca1e37d92c..3997957d25 100644
--- a/src/corelib/io/qstandardpaths.h
+++ b/src/corelib/io/qstandardpaths.h
@@ -38,7 +38,9 @@ public:
         AppDataLocation,
         AppConfigLocation,
         PublicShareLocation,
-        TemplatesLocation
+        TemplatesLocation,
+        StateLocation,
+        GenericStateLocation
     };
     Q_ENUM(StandardLocation)
 
diff --git a/src/corelib/io/qstandardpaths_android.cpp b/src/corelib/io/qstandardpaths_android.cpp
index e058f379c2..f605752ffa 100644
--- a/src/corelib/io/qstandardpaths_android.cpp
+++ b/src/corelib/io/qstandardpaths_android.cpp
@@ -195,6 +195,9 @@ QString QStandardPaths::writableLocation(StandardLocation type)
     case QStandardPaths::ConfigLocation:
     case QStandardPaths::AppConfigLocation:
         return getFilesDir() + testDir() + "/settings"_L1;
+    case QStandardPaths::StateLocation:
+    case QStandardPaths::GenericStateLocation:
+        return getFilesDir() + testDir() + "/state"_L1;
     case QStandardPaths::GenericDataLocation:
     {
         return QAndroidApplication::sdkVersion() >= 30 ?
diff --git a/src/corelib/io/qstandardpaths_haiku.cpp b/src/corelib/io/qstandardpaths_haiku.cpp
index 6122e5f6f9..93eba134f3 100644
--- a/src/corelib/io/qstandardpaths_haiku.cpp
+++ b/src/corelib/io/qstandardpaths_haiku.cpp
@@ -120,8 +120,10 @@ QString QStandardPaths::writableLocation(StandardLocation type)
         return haikuAppStandardPath(B_USER_CACHE_DIRECTORY);
     case GenericCacheLocation:
         return haikuStandardPath(B_USER_CACHE_DIRECTORY);
-    case ConfigLocation: // fall through
+    case ConfigLocation:
     case AppConfigLocation:
+    case StateLocation:
+    case GenericStateLocation:
         return haikuAppStandardPath(B_USER_SETTINGS_DIRECTORY);
     case GenericConfigLocation:
         return haikuStandardPath(B_USER_SETTINGS_DIRECTORY);
diff --git a/src/corelib/io/qstandardpaths_mac.mm b/src/corelib/io/qstandardpaths_mac.mm
index 5a41ae8e92..2acbe92736 100644
--- a/src/corelib/io/qstandardpaths_mac.mm
+++ b/src/corelib/io/qstandardpaths_mac.mm
@@ -120,6 +120,12 @@ static QString baseWritableLocation(QStandardPaths::StandardLocation type,
     case QStandardPaths::AppConfigLocation:
         path = pathForDirectory(NSLibraryDirectory, mask) + "/Preferences"_L1;
         break;
+    case QStandardPaths::StateLocation:
+        if (appendOrgAndApp) { break; }
+        Q_FALLTHROUGH();
+    case QStandardPaths::GenericStateLocation:
+        path = pathForDirectory(NSLibraryDirectory, mask) + "/Preferences/State"_L1;
+        break;
     default:
         path = pathForDirectory(dir, mask);
         break;
@@ -133,6 +139,11 @@ static QString baseWritableLocation(QStandardPaths::StandardLocation type,
         case QStandardPaths::CacheLocation:
             appendOrganizationAndApp(path);
             break;
+        case QStandardPaths::StateLocation:
+            path = pathForDirectory(NSLibraryDirectory, mask) + "/Preferences"_L1;
+            appendOrganizationAndApp(path);
+            path += "/State"_L1;
+            break;
         default:
             break;
         }
diff --git a/src/corelib/io/qstandardpaths_unix.cpp b/src/corelib/io/qstandardpaths_unix.cpp
index 64d8a3fa49..e38f670895 100644
--- a/src/corelib/io/qstandardpaths_unix.cpp
+++ b/src/corelib/io/qstandardpaths_unix.cpp
@@ -196,6 +196,25 @@ QString QStandardPaths::writableLocation(StandardLocation type)
             appendOrganizationAndApp(xdgCacheHome);
         return xdgCacheHome;
     }
+    case StateLocation:
+    case GenericStateLocation:
+    {
+        QString xdgStateHome;
+        if (isTestModeEnabled()) {
+            xdgStateHome = QDir::homePath() + "/.qttest/state"_L1;
+        } else {
+            // http://standards.freedesktop.org/basedir-spec/basedir-spec-0.8.html
+            xdgStateHome = QFile::decodeName(qgetenv("XDG_STATE_HOME"));
+            if (!xdgStateHome.startsWith(u'/'))
+                xdgStateHome.clear(); // spec says relative paths should be ignored
+
+            if (xdgStateHome.isEmpty())
+                xdgStateHome = QDir::homePath() + "/.local/state"_L1;
+        }
+        if (type == QStandardPaths::StateLocation)
+            appendOrganizationAndApp(xdgStateHome);
+        return xdgStateHome;
+    }
     case AppDataLocation:
     case AppLocalDataLocation:
     case GenericDataLocation:
diff --git a/src/corelib/io/qstandardpaths_win.cpp b/src/corelib/io/qstandardpaths_win.cpp
index 13b8fe224a..805ce65a5a 100644
--- a/src/corelib/io/qstandardpaths_win.cpp
+++ b/src/corelib/io/qstandardpaths_win.cpp
@@ -105,8 +105,10 @@ static GUID writableSpecialFolderId(QStandardPaths::StandardLocation type)
         FOLDERID_LocalAppData,  // AppConfigLocation ("Local" path)
         FOLDERID_Public,        // PublicShareLocation
         FOLDERID_Templates,     // TemplatesLocation
+        GUID(),                  // StateLocation
+        GUID(),                  // GenericStateLocation
     };
-    static_assert(sizeof(folderIds) / sizeof(folderIds[0]) == size_t(QStandardPaths::TemplatesLocation + 1));
+    static_assert(sizeof(folderIds) / sizeof(folderIds[0]) == size_t(QStandardPaths::GenericStateLocation + 1));
 
     // folders for low integrity processes
     static const GUID folderIds_li[] = {
@@ -130,6 +132,8 @@ static GUID writableSpecialFolderId(QStandardPaths::StandardLocation type)
         FOLDERID_LocalAppDataLow,// AppConfigLocation ("Local" path)
         FOLDERID_Public,         // PublicShareLocation
         FOLDERID_Templates,      // TemplatesLocation
+        GUID(),                  // StateLocation
+        GUID(),                  // GenericStateLocation
     };
     static_assert(sizeof(folderIds_li) == sizeof(folderIds));
 
@@ -184,6 +188,23 @@ QString QStandardPaths::writableLocation(StandardLocation type)
         result = QDir::tempPath();
         break;
 
+    case StateLocation:
+        result = sHGetKnownFolderPath(writableSpecialFolderId(AppLocalDataLocation));
+        if (!result.isEmpty()) {
+            appendTestMode(result);
+            appendOrganizationAndApp(result);
+            result += "/State"_L1;
+        }
+        break;
+
+    case GenericStateLocation:
+        result = sHGetKnownFolderPath(writableSpecialFolderId(GenericDataLocation));
+        if (!result.isEmpty()) {
+            appendTestMode(result);
+            result += "/State"_L1;
+        }
+        break;
+
     default:
         result = sHGetKnownFolderPath(writableSpecialFolderId(type));
         if (!result.isEmpty() && isConfigLocation(type)) {
diff --git a/src/tools/qtpaths/qtpaths.cpp b/src/tools/qtpaths/qtpaths.cpp
index db101efca5..a840f08ba6 100644
--- a/src/tools/qtpaths/qtpaths.cpp
+++ b/src/tools/qtpaths/qtpaths.cpp
@@ -71,12 +71,14 @@ static const StringEnum lookupTableData[] = {
     { "GenericCacheLocation", QStandardPaths::GenericCacheLocation, false },
     { "GenericConfigLocation", QStandardPaths::GenericConfigLocation, false },
     { "GenericDataLocation", QStandardPaths::GenericDataLocation, false },
+    { "GenericStateLocation", QStandardPaths::GenericStateLocation, false },
     { "HomeLocation", QStandardPaths::HomeLocation, false },
     { "MoviesLocation", QStandardPaths::MoviesLocation, false },
     { "MusicLocation", QStandardPaths::MusicLocation, false },
     { "PicturesLocation", QStandardPaths::PicturesLocation, false },
     { "PublicShareLocation", QStandardPaths::PublicShareLocation, false },
     { "RuntimeLocation", QStandardPaths::RuntimeLocation, false },
+    { "StateLocation", QStandardPaths::StateLocation, true },
     { "TemplatesLocation", QStandardPaths::TemplatesLocation, false },
     { "TempLocation", QStandardPaths::TempLocation, false }
 };
diff --git a/tests/auto/corelib/io/qstandardpaths/tst_qstandardpaths.cpp b/tests/auto/corelib/io/qstandardpaths/tst_qstandardpaths.cpp
index b59cf2bf3a..cc81b6ac7a 100644
--- a/tests/auto/corelib/io/qstandardpaths/tst_qstandardpaths.cpp
+++ b/tests/auto/corelib/io/qstandardpaths/tst_qstandardpaths.cpp
@@ -27,7 +27,7 @@
 using namespace Qt::StringLiterals;
 
 // Update this when adding new enum values; update enumNames too
-static const int MaxStandardLocation = QStandardPaths::AppConfigLocation;
+static const int MaxStandardLocation = QStandardPaths::GenericStateLocation;
 
 static QString genericCacheLoc()
 {
@@ -38,6 +38,15 @@ static QString cacheLoc()
     return QStandardPaths::writableLocation(QStandardPaths::CacheLocation);
 }
 
+static QString genericStateLoc()
+{
+    return QStandardPaths::writableLocation(QStandardPaths::GenericStateLocation);
+}
+static QString stateLoc()
+{
+    return QStandardPaths::writableLocation(QStandardPaths::StateLocation);
+}
+
 static QString genericDataLoc()
 {
     return QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation);
@@ -98,14 +107,17 @@ private:
         qputenv("XDG_CONFIG_DIRS", QFile::encodeName(m_globalConfigDir));
         m_localAppDir = m_localAppTempDir.path();
         m_globalAppDir = m_globalAppTempDir.path();
+        m_stateDir = m_stateTempDir.path();
         qputenv("XDG_DATA_HOME", QFile::encodeName(m_localAppDir));
         qputenv("XDG_DATA_DIRS", QFile::encodeName(m_globalAppDir));
+        qputenv("XDG_STATE_HOME", QFile::encodeName(m_stateDir));
     }
     void setDefaultLocations() {
         qputenv("XDG_CONFIG_HOME", nullptr);
         qputenv("XDG_CONFIG_DIRS", nullptr);
         qputenv("XDG_DATA_HOME", nullptr);
         qputenv("XDG_DATA_DIRS", nullptr);
+        qputenv("XDG_STATE_HOME", nullptr);
     }
 #endif
 
@@ -120,6 +132,8 @@ private:
     QTemporaryDir m_localAppTempDir;
     QString m_globalAppDir;
     QTemporaryDir m_globalAppTempDir;
+    QString m_stateDir;
+    QTemporaryDir m_stateTempDir;
 };
 
 static const char * const enumNames[MaxStandardLocation + 1 - int(QStandardPaths::DesktopLocation)] = {
@@ -141,7 +155,11 @@ static const char * const enumNames[MaxStandardLocation + 1 - int(QStandardPaths
     "GenericCacheLocation",
     "GenericConfigLocation",
     "AppDataLocation",
-    "AppConfigLocation"
+    "AppConfigLocation",
+    "PublicShareLocation",
+    "TemplatesLocation",
+    "StateLocation",
+    "GenericStateLocation"
 };
 
 void tst_qstandardpaths::initTestCase()
@@ -160,6 +178,7 @@ void tst_qstandardpaths::initTestCase()
     QVERIFY2(m_globalConfigTempDir.isValid(), qPrintable(m_globalConfigTempDir.errorString()));
     QVERIFY2(m_localAppTempDir.isValid(), qPrintable(m_localAppTempDir.errorString()));
     QVERIFY2(m_globalAppTempDir.isValid(), qPrintable(m_globalAppTempDir.errorString()));
+    QVERIFY2(m_stateTempDir.isValid(), qPrintable(m_stateTempDir.errorString()));
 }
 
 void tst_qstandardpaths::dump()
@@ -205,6 +224,8 @@ void tst_qstandardpaths::testDefaultLocations()
     QCOMPARE(genericDataDirs.at(0), expectedDataHome);
     QCOMPARE(genericDataDirs.at(1), QString::fromLatin1("/usr/local/share"));
     QCOMPARE(genericDataDirs.at(2), QString::fromLatin1("/usr/share"));
+    const QString expectedGenericStateLocation = QDir::homePath() + QString::fromLatin1("/.local/state");
+    QCOMPARE(genericStateLoc(), expectedGenericStateLocation);
 #endif
 }
 
@@ -283,25 +304,34 @@ void tst_qstandardpaths::enableTestMode()
     // CacheLocation should be "GenericCacheLocation/organization-name/app-name"
     QCOMPARE(cacheLoc(), cacheDir + "/tst_qstandardpaths"_L1);
 
+    // *StateLocation
+    const QString stateDir = qttestDir + QLatin1String("/state");
+    QCOMPARE(genericStateLoc(), stateDir);
+    const QStringList stateDirs = QStandardPaths::standardLocations(QStandardPaths::GenericStateLocation);
+    QCOMPARE(stateDirs, QStringList() << stateDir);
+    // StateLocation should be "GenericStateLocation/organization-name/app-name"
+    QCOMPARE(stateLoc(), stateDir + "/tst_qstandardpaths"_L1);
+
     QCoreApplication::setOrganizationName("Qt");
     QCOMPARE(appConfigLoc(), configDir + "/Qt/tst_qstandardpaths"_L1);
     QCOMPARE(appDataLoc(), dataDir + "/Qt/tst_qstandardpaths"_L1);
     QCOMPARE(appLocalDataLoc(), dataDir + "/Qt/tst_qstandardpaths"_L1);
     QCOMPARE(cacheLoc(), cacheDir + "/Qt/tst_qstandardpaths"_L1);
-    QCOMPARE(cacheLoc(), cacheDir + "/Qt/tst_qstandardpaths"_L1);
+    QCOMPARE(stateLoc(), stateDir + "/Qt/tst_qstandardpaths"_L1);
 
     QCoreApplication::setApplicationName("QtTest");
     QCOMPARE(appConfigLoc(), configDir + "/Qt/QtTest"_L1);
     QCOMPARE(appDataLoc(), dataDir + "/Qt/QtTest"_L1);
     QCOMPARE(appLocalDataLoc(), dataDir + "/Qt/QtTest"_L1);
-    QCoreApplication::setApplicationName("QtTest");
     QCOMPARE(cacheLoc(), cacheDir + "/Qt/QtTest"_L1);
+    QCOMPARE(stateLoc(), stateDir + "/Qt/QtTest"_L1);
 
     // Check these are unaffected by org/app names
     QCOMPARE(genericConfigLoc(), configDir);
     QCOMPARE(configLoc(), configDir);
     QCOMPARE(genericDataLoc(), dataDir);
     QCOMPARE(genericCacheLoc(), cacheDir);
+    QCOMPARE(genericStateLoc(), stateDir);
 #endif
 
     // On all platforms, we want to ensure that the writableLocation is different in test mode and real mode.
@@ -315,6 +345,8 @@ void tst_qstandardpaths::enableTestMode()
     testLocations.insert(QStandardPaths::GenericConfigLocation, genericConfigLoc());
     testLocations.insert(QStandardPaths::CacheLocation, cacheLoc());
     testLocations.insert(QStandardPaths::GenericCacheLocation, genericCacheLoc());
+    testLocations.insert(QStandardPaths::StateLocation, stateLoc());
+    testLocations.insert(QStandardPaths::GenericStateLocation, genericStateLoc());
     // On Windows, what should "Program Files" become, in test mode?
     //testLocations.insert(QStandardPaths::ApplicationsLocation, QStandardPaths::writableLocation(QStandardPaths::ApplicationsLocation));
 
@@ -807,6 +839,10 @@ void tst_qstandardpaths::testXdgPathCleanup()
     const QString cacheDir = cacheLoc();
     QCOMPARE_NE(cacheDir, relative);
 
+    qputenv("XDG_STATE_HOME", relative.toLatin1());
+    const QString stateDir = stateLoc();
+    QCOMPARE_NE(stateDir, relative);
+
     qputenv("XDG_DATA_HOME", relative.toLatin1());
     const QString localDataDir = genericDataLoc();
     QCOMPARE_NE(localDataDir, relative);