Add support for opening links in incognito mode on Linux & BSD (#4745)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

CHANGELOG.md

@@ -23,6 +23,8 @@
 - Minor: All channels opened in browser tabs are synced when using the extension for quicker switching between tabs. (#4741)
 - Minor: Show channel point redemptions without messages in usercard. (#4557)
 - Minor: Allow for customizing the behavior of `Right Click`ing of usernames. (#4622, #4751)
+- Minor: Added support for opening incognito links in firefox-esr and chromium. (#4745)
+- Minor: Added support for opening incognito links under Linux/BSD using XDG. (#4745)
 - Bugfix: Increased amount of blocked users loaded from 100 to 1,000. (#4721)
 - Bugfix: Fixed generation of crashdumps by the browser-extension process when the browser was closed. (#4667)
 - Bugfix: Fix spacing issue with mentions inside RTL text. (#4677)
@@ -55,6 +57,7 @@
 - Dev: Added the ability to use an alternate linker using the `-DUSE_ALTERNATE_LINKER=...` CMake parameter. (#4711)
 - Dev: The Windows installer is now built in CI. (#4408)
 - Dev: Removed `getApp` and `getSettings` calls from message rendering. (#4535)
+- Dev: Get the default browser executable instead of the entire command line when opening incognito links. (#4745)
 
 ## 2.4.4
 

src/CMakeLists.txt

@@ -438,6 +438,12 @@ set(SOURCE_FILES
         util/TypeName.hpp
         util/WindowsHelper.cpp
         util/WindowsHelper.hpp
+        util/XDGDesktopFile.cpp
+        util/XDGDesktopFile.hpp
+        util/XDGDirectory.cpp
+        util/XDGDirectory.hpp
+        util/XDGHelper.cpp
+        util/XDGHelper.hpp
 
         util/serialize/Container.hpp
 

src/common/QLogging.cpp

@@ -55,3 +55,4 @@ Q_LOGGING_CATEGORY(chatterinoWebsocket, "chatterino.websocket", logThreshold);
 Q_LOGGING_CATEGORY(chatterinoWidget, "chatterino.widget", logThreshold);
 Q_LOGGING_CATEGORY(chatterinoWindowmanager, "chatterino.windowmanager",
                    logThreshold);
+Q_LOGGING_CATEGORY(chatterinoXDG, "chatterino.xdg", logThreshold);

src/common/QLogging.hpp

@@ -42,3 +42,4 @@ Q_DECLARE_LOGGING_CATEGORY(chatterinoUpdate);
 Q_DECLARE_LOGGING_CATEGORY(chatterinoWebsocket);
 Q_DECLARE_LOGGING_CATEGORY(chatterinoWidget);
 Q_DECLARE_LOGGING_CATEGORY(chatterinoWindowmanager);
+Q_DECLARE_LOGGING_CATEGORY(chatterinoXDG);

src/util/IncognitoBrowser.cpp

@@ -1,88 +1,93 @@
 #include "util/IncognitoBrowser.hpp"
 #ifdef USEWINSDK
 #    include "util/WindowsHelper.hpp"
+#elif defined(Q_OS_UNIX) and !defined(Q_OS_DARWIN)
+#    include "util/XDGHelper.hpp"
 #endif
 
 #include <QProcess>
-#include <QRegularExpression>
 #include <QVariant>
 
 namespace {
 
 using namespace chatterino;
 
-#ifdef USEWINSDK
+QString getPrivateSwitch(const QString &browserExecutable)
-QString injectPrivateSwitch(QString command)
 {
     // list of command line switches to turn on private browsing in browsers
     static auto switches = std::vector<std::pair<QString, QString>>{
-        {"firefox", "-private-window"},  {"librewolf", "-private-window"},
+        {"firefox", "-private-window"},     {"librewolf", "-private-window"},
-        {"waterfox", "-private-window"}, {"icecat", "-private-window"},
+        {"waterfox", "-private-window"},    {"icecat", "-private-window"},
-        {"chrome", "-incognito"},        {"vivaldi", "-incognito"},
+        {"chrome", "-incognito"},           {"vivaldi", "-incognito"},
-        {"opera", "-newprivatetab"},     {"opera\\\\launcher", "--private"},
+        {"opera", "-newprivatetab"},        {"opera\\launcher", "--private"},
-        {"iexplore", "-private"},        {"msedge", "-inprivate"},
+        {"iexplore", "-private"},           {"msedge", "-inprivate"},
+        {"firefox-esr", "-private-window"}, {"chromium", "-incognito"},
     };
 
-    // transform into regex and replacement string
+    // compare case-insensitively
-    std::vector<std::pair<QRegularExpression, QString>> replacers;
+    auto lowercasedBrowserExecutable = browserExecutable.toLower();
+
+#ifdef Q_OS_WINDOWS
+    if (lowercasedBrowserExecutable.endsWith(".exe"))
+    {
+        lowercasedBrowserExecutable.chop(4);
+    }
+#endif
+
     for (const auto &switch_ : switches)
     {
-        replacers.emplace_back(
+        if (lowercasedBrowserExecutable.endsWith(switch_.first))
-            QRegularExpression("(" + switch_.first + "\\.exe\"?).*",
-                               QRegularExpression::CaseInsensitiveOption),
-            "\\1 " + switch_.second);
-    }
-
-    // try to find matching regex and apply it
-    for (const auto &replacement : replacers)
-    {
-        if (replacement.first.match(command).hasMatch())
         {
-            command.replace(replacement.first, replacement.second);
+            return switch_.second;
-            return command;
         }
     }
 
     // couldn't match any browser -> unknown browser
-    return QString();
+    return {};
 }
 
-QString getCommand()
+QString getDefaultBrowserExecutable()
 {
+#ifdef USEWINSDK
     // get default browser start command, by protocol if possible, falling back to extension if not
     QString command =
-        getAssociatedCommand(AssociationQueryType::Protocol, L"http");
+        getAssociatedExecutable(AssociationQueryType::Protocol, L"http");
 
     if (command.isNull())
     {
         // failed to fetch default browser by protocol, try by file extension instead
-        command =
+        command = getAssociatedExecutable(AssociationQueryType::FileExtension,
-            getAssociatedCommand(AssociationQueryType::FileExtension, L".html");
+                                          L".html");
     }
 
     if (command.isNull())
     {
         // also try the equivalent .htm extension
-        command =
+        command = getAssociatedExecutable(AssociationQueryType::FileExtension,
-            getAssociatedCommand(AssociationQueryType::FileExtension, L".htm");
+                                          L".htm");
-    }
-
-    if (command.isNull())
-    {
-        // failed to find browser command
-        return QString();
-    }
-
-    // inject switch to enable private browsing
-    command = injectPrivateSwitch(command);
-    if (command.isNull())
-    {
-        return QString();
     }
 
     return command;
-}
+#elif defined(Q_OS_UNIX) && !defined(Q_OS_DARWIN)
+    static QString defaultBrowser = []() -> QString {
+        auto desktopFile = getDefaultBrowserDesktopFile();
+        if (desktopFile.has_value())
+        {
+            auto entry = desktopFile->getEntries("Desktop Entry");
+            auto exec = entry.find("Exec");
+            if (exec != entry.end())
+            {
+                return parseDesktopExecProgram(exec->second.trimmed());
+            }
+        }
+        return {};
+    }();
+
+    return defaultBrowser;
+#else
+    return {};
 #endif
+}
 
 }  // namespace
 
@@ -90,23 +95,15 @@ namespace chatterino {
 
 bool supportsIncognitoLinks()
 {
-#ifdef USEWINSDK
+    auto browserExe = getDefaultBrowserExecutable();
-    return !getCommand().isNull();
+    return !browserExe.isNull() && !getPrivateSwitch(browserExe).isNull();
-#else
-    return false;
-#endif
 }
 
 bool openLinkIncognito(const QString &link)
 {
-#ifdef USEWINSDK
+    auto browserExe = getDefaultBrowserExecutable();
-    auto command = getCommand();
+    return QProcess::startDetached(browserExe,
-
+                                   {getPrivateSwitch(browserExe), link});
-    // TODO: split command into program path and incognito argument
-    return QProcess::startDetached(command, {link});
-#else
-    return false;
-#endif
 }
 
 }  // namespace chatterino

src/util/WindowsHelper.cpp

@@ -88,7 +88,7 @@ void setRegisteredForStartup(bool isRegistered)
     }
 }
 
-QString getAssociatedCommand(AssociationQueryType queryType, LPCWSTR query)
+QString getAssociatedExecutable(AssociationQueryType queryType, LPCWSTR query)
 {
     static HINSTANCE shlwapi = LoadLibrary(L"shlwapi");
     if (shlwapi == nullptr)
@@ -122,7 +122,7 @@ QString getAssociatedCommand(AssociationQueryType queryType, LPCWSTR query)
     }
 
     DWORD resultSize = 0;
-    if (FAILED(assocQueryString(flags, ASSOCSTR_COMMAND, query, nullptr,
+    if (FAILED(assocQueryString(flags, ASSOCSTR_EXECUTABLE, query, nullptr,
                                 nullptr, &resultSize)))
     {
         return QString();
@@ -137,8 +137,8 @@ QString getAssociatedCommand(AssociationQueryType queryType, LPCWSTR query)
 
     QString result;
     auto buf = new wchar_t[resultSize];
-    if (SUCCEEDED(assocQueryString(flags, ASSOCSTR_COMMAND, query, nullptr, buf,
+    if (SUCCEEDED(assocQueryString(flags, ASSOCSTR_EXECUTABLE, query, nullptr,
-                                   &resultSize)))
+                                   buf, &resultSize)))
     {
         // QString::fromWCharArray expects the length in characters *not
         // including* the null terminator, but AssocQueryStringW calculates

src/util/WindowsHelper.hpp

@@ -16,7 +16,7 @@ void flushClipboard();
 bool isRegisteredForStartup();
 void setRegisteredForStartup(bool isRegistered);
 
-QString getAssociatedCommand(AssociationQueryType queryType, LPCWSTR query);
+QString getAssociatedExecutable(AssociationQueryType queryType, LPCWSTR query);
 
 }  // namespace chatterino
 

src/util/XDGDesktopFile.cpp

@@ -0,0 +1,118 @@
+#include "util/XDGDesktopFile.hpp"
+
+#include "util/XDGDirectory.hpp"
+
+#include <QDir>
+#include <QFile>
+
+#include <functional>
+
+#if defined(Q_OS_UNIX) and !defined(Q_OS_DARWIN)
+
+namespace chatterino {
+
+XDGDesktopFile::XDGDesktopFile(const QString &filename)
+{
+    QFile file(filename);
+    if (!file.open(QIODevice::ReadOnly))
+    {
+        return;
+    }
+    this->valid = true;
+
+    std::optional<std::reference_wrapper<XDGEntries>> entries;
+
+    while (!file.atEnd())
+    {
+        auto lineBytes = file.readLine().trimmed();
+
+        // Ignore comments & empty lines
+        if (lineBytes.startsWith('#') || lineBytes.size() == 0)
+        {
+            continue;
+        }
+
+        auto line = QString::fromUtf8(lineBytes);
+
+        if (line.startsWith('['))
+        {
+            // group header
+            auto end = line.indexOf(']', 1);
+            if (end == -1 || end == 1)
+            {
+                // malformed header - either empty or no closing bracket
+                continue;
+            }
+            auto groupName = line.mid(1, end - 1);
+
+            // it is against spec for the group name to already exist, but the
+            // parsing behavior for that case is not specified. operator[] will
+            // result in duplicate groups being merged, which makes the most
+            // sense for a read-only parser
+            entries = this->groups[groupName];
+
+            continue;
+        }
+
+        // group entry
+        if (!entries.has_value())
+        {
+            // no group header yet, entry before a group header is against spec
+            // and should be ignored
+            continue;
+        }
+
+        auto delimiter = line.indexOf('=');
+        if (delimiter == -1)
+        {
+            // line is not a group header or a key value pair, ignore it
+            continue;
+        }
+
+        auto key = QStringView(line).left(delimiter).trimmed().toString();
+        // QStringView.mid() does not do bounds checking before qt 5.15, so
+        // we have to do it ourselves
+        auto valueStart = delimiter + 1;
+        QString value;
+        if (valueStart < line.size())
+        {
+            value = QStringView(line).mid(valueStart).trimmed().toString();
+        }
+
+        // existing keys are against spec, so we can overwrite them with
+        // wild abandon
+        entries->get().emplace(key, value);
+    }
+}
+
+XDGEntries XDGDesktopFile::getEntries(const QString &groupHeader) const
+{
+    auto group = this->groups.find(groupHeader);
+    if (group != this->groups.end())
+    {
+        return group->second;
+    }
+
+    return {};
+}
+
+std::optional<XDGDesktopFile> XDGDesktopFile::findDesktopFile(
+    const QString &desktopFileID)
+{
+    for (const auto &dataDir : getXDGDirectories(XDGDirectoryType::Data))
+    {
+        auto fileName =
+            QDir::cleanPath(dataDir + QDir::separator() + "applications" +
+                            QDir::separator() + desktopFileID);
+        XDGDesktopFile desktopFile(fileName);
+        if (desktopFile.isValid())
+        {
+            return desktopFile;
+        }
+    }
+    return {};
+}
+
+}  // namespace chatterino
+
+#endif

src/util/XDGDesktopFile.hpp

@@ -0,0 +1,49 @@
+#pragma once
+
+#include "util/QStringHash.hpp"
+
+#include <optional>
+#include <unordered_map>
+
+#if defined(Q_OS_UNIX) and !defined(Q_OS_DARWIN)
+
+namespace chatterino {
+
+// See https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html#group-header
+using XDGEntries = std::unordered_map<QString, QString>;
+
+class XDGDesktopFile
+{
+public:
+    // Read the file at `filename` as an XDG desktop file, parsing its groups & their entries
+    //
+    // Use the `isValid` function to check if the file was read properly
+    explicit XDGDesktopFile(const QString &filename);
+
+    /// Returns a map of entries for the given group header
+    XDGEntries getEntries(const QString &groupHeader) const;
+
+    /// isValid returns true if the file exists and is readable
+    bool isValid() const
+    {
+        return valid;
+    }
+
+    /// Find the first desktop file based on the given desktop file ID
+    ///
+    /// This will look through all Data XDG directories
+    ///
+    /// Can return std::nullopt if no desktop file was found for the given desktop file ID
+    ///
+    /// References: https://specifications.freedesktop.org/desktop-entry-spec/latest/ar01s02.html#desktop-file-id
+    static std::optional<XDGDesktopFile> findDesktopFile(
+        const QString &desktopFileID);
+
+private:
+    bool valid{};
+    std::unordered_map<QString, XDGEntries> groups;
+};
+
+}  // namespace chatterino
+
+#endif

src/util/XDGDirectory.cpp

@@ -0,0 +1,77 @@
+#include "util/XDGDirectory.hpp"
+
+#include "util/CombinePath.hpp"
+#include "util/Qt.hpp"
+
+namespace chatterino {
+
+#if defined(Q_OS_UNIX) and !defined(Q_OS_DARWIN)
+
+QStringList getXDGDirectories(XDGDirectoryType directory)
+{
+    // User XDG directory environment variables with defaults
+    // Defaults fetched from https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html#variables 2023-08-05
+    static std::unordered_map<XDGDirectoryType,
+                              std::pair<const char *, QString>>
+        userDirectories = {
+            {
+                XDGDirectoryType::Config,
+                {
+                    "XDG_CONFIG_HOME",
+                    combinePath(QDir::homePath(), ".config/"),
+                },
+            },
+            {
+                XDGDirectoryType::Data,
+                {
+                    "XDG_DATA_HOME",
+                    combinePath(QDir::homePath(), ".local/share/"),
+                },
+            },
+        };
+
+    // Base (or system) XDG directory environment variables with defaults
+    // Defaults fetched from https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html#variables 2023-08-05
+    static std::unordered_map<XDGDirectoryType,
+                              std::pair<const char *, QStringList>>
+        baseDirectories = {
+            {
+                XDGDirectoryType::Config,
+                {
+                    "XDG_CONFIG_DIRS",
+                    {"/etc/xdg"},
+                },
+            },
+            {
+                XDGDirectoryType::Data,
+                {
+                    "XDG_DATA_DIRS",
+                    {"/usr/local/share/", "/usr/share/"},
+                },
+            },
+        };
+
+    QStringList paths;
+
+    const auto &[userEnvVar, userDefaultValue] = userDirectories.at(directory);
+    auto userEnvPath = qEnvironmentVariable(userEnvVar, userDefaultValue);
+    paths.push_back(userEnvPath);
+
+    const auto &[baseEnvVar, baseDefaultValue] = baseDirectories.at(directory);
+    auto baseEnvPaths =
+        qEnvironmentVariable(baseEnvVar).split(':', Qt::SkipEmptyParts);
+    if (baseEnvPaths.isEmpty())
+    {
+        paths.append(baseDefaultValue);
+    }
+    else
+    {
+        paths.append(baseEnvPaths);
+    }
+
+    return paths;
+}
+
+#endif
+
+}  // namespace chatterino

src/util/XDGDirectory.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <QStringList>
+
+namespace chatterino {
+
+#if defined(Q_OS_UNIX) and !defined(Q_OS_DARWIN)
+
+enum class XDGDirectoryType {
+    Config,
+    Data,
+};
+
+/// getXDGDirectories returns a list of directories given a directory type
+///
+/// This will attempt to read the relevant environment variable (e.g. XDG_CONFIG_HOME and XDG_CONFIG_DIRS) and merge them, with sane defaults
+QStringList getXDGDirectories(XDGDirectoryType directory);
+
+#endif
+
+}  // namespace chatterino

src/util/XDGHelper.cpp

@@ -0,0 +1,259 @@
+#include "util/XDGHelper.hpp"
+
+#include "common/Literals.hpp"
+#include "common/QLogging.hpp"
+#include "util/CombinePath.hpp"
+#include "util/Qt.hpp"
+#include "util/XDGDesktopFile.hpp"
+#include "util/XDGDirectory.hpp"
+
+#include <QDebug>
+#include <QProcess>
+#include <QRegularExpression>
+#include <QSettings>
+#include <QStringLiteral>
+#include <QTextCodec>
+#include <QtGlobal>
+
+#include <unordered_set>
+
+#if defined(Q_OS_UNIX) and !defined(Q_OS_DARWIN)
+
+using namespace chatterino::literals;
+
+namespace {
+
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+const auto &LOG = chatterinoXDG;
+
+using namespace chatterino;
+
+const auto HTTPS_MIMETYPE = u"x-scheme-handler/https"_s;
+
+/// Read the given mimeapps file and try to find an association for the HTTPS_MIMETYPE
+///
+/// If the mimeapps file is invalid (i.e. wasn't read), return nullopt
+/// If the file is valid, look for the default Desktop File ID handler for the HTTPS_MIMETYPE
+/// If no default Desktop File ID handler is found, populate `associations`
+///   and `denyList` with Desktop File IDs from "Added Associations" and "Removed Associations" respectively
+std::optional<XDGDesktopFile> processMimeAppsList(
+    const QString &mimeappsPath, QStringList &associations,
+    std::unordered_set<QString> &denyList)
+{
+    XDGDesktopFile mimeappsFile(mimeappsPath);
+    if (!mimeappsFile.isValid())
+    {
+        return {};
+    }
+
+    // get the list of Desktop File IDs for the given mimetype under the "Default
+    // Applications" group in the mimeapps.list file
+    auto defaultGroup = mimeappsFile.getEntries("Default Applications");
+    auto defaultApps = defaultGroup.find(HTTPS_MIMETYPE);
+    if (defaultApps != defaultGroup.cend())
+    {
+        // for each desktop ID in the list:
+        auto desktopIds = defaultApps->second.split(';', Qt::SkipEmptyParts);
+        for (const auto &entry : desktopIds)
+        {
+            auto desktopId = entry.trimmed();
+
+            // if a valid desktop file is found, verify that it is associated
+            // with the type. being in the default list gives it an implicit
+            // association, so just check that it's not in the denylist
+            if (!denyList.contains(desktopId))
+            {
+                auto desktopFile = XDGDesktopFile::findDesktopFile(desktopId);
+                // if a valid association is found, we have found the default
+                // application
+                if (desktopFile.has_value())
+                {
+                    return desktopFile;
+                }
+            }
+        }
+    }
+
+    // no definitive default application found. process added and removed
+    // associations, then return empty
+
+    // load any removed associations into the denylist
+    auto removedGroup = mimeappsFile.getEntries("Removed Associations");
+    auto removedApps = removedGroup.find(HTTPS_MIMETYPE);
+    if (removedApps != removedGroup.end())
+    {
+        auto desktopIds = removedApps->second.split(';', Qt::SkipEmptyParts);
+        for (const auto &entry : desktopIds)
+        {
+            denyList.insert(entry.trimmed());
+        }
+    }
+
+    // append any created associations to the associations list
+    auto addedGroup = mimeappsFile.getEntries("Added Associations");
+    auto addedApps = addedGroup.find(HTTPS_MIMETYPE);
+    if (addedApps != addedGroup.end())
+    {
+        auto desktopIds = addedApps->second.split(';', Qt::SkipEmptyParts);
+        for (const auto &entry : desktopIds)
+        {
+            associations.push_back(entry.trimmed());
+        }
+    }
+
+    return {};
+}
+
+std::optional<XDGDesktopFile> searchMimeAppsListsInDirectory(
+    const QString &directory, QStringList &associations,
+    std::unordered_set<QString> &denyList)
+{
+    static auto desktopNames = qEnvironmentVariable("XDG_CURRENT_DESKTOP")
+                                   .split(':', Qt::SkipEmptyParts);
+    static const QString desktopFilename = QStringLiteral("%1-mimeapps.list");
+    static const QString nonDesktopFilename = QStringLiteral("mimeapps.list");
+
+    // try desktop specific mimeapps.list files first
+    for (const auto &desktopName : desktopNames)
+    {
+        auto fileName =
+            combinePath(directory, desktopFilename.arg(desktopName));
+        auto defaultApp = processMimeAppsList(fileName, associations, denyList);
+        if (defaultApp.has_value())
+        {
+            return defaultApp;
+        }
+    }
+
+    // try the generic mimeapps.list
+    auto fileName = combinePath(directory, nonDesktopFilename);
+    auto defaultApp = processMimeAppsList(fileName, associations, denyList);
+    if (defaultApp.has_value())
+    {
+        return defaultApp;
+    }
+
+    // no definitive default application found
+    return {};
+}
+
+}  // namespace
+
+namespace chatterino {
+
+/// Try to figure out the most reasonably default web browser to use
+///
+/// If the `xdg-settings` program is available, use that
+/// If not, read through all possible mimapps files in the order specified here: https://specifications.freedesktop.org/mime-apps-spec/mime-apps-spec-1.0.1.html#file
+/// If no mimeapps file has a default, try to use the Added Associations in those files
+std::optional<XDGDesktopFile> getDefaultBrowserDesktopFile()
+{
+    // no xdg-utils, find it manually by searching mimeapps.list files
+    QStringList associations;
+    std::unordered_set<QString> denyList;
+
+    // config dirs first
+    for (const auto &configDir : getXDGDirectories(XDGDirectoryType::Config))
+    {
+        auto defaultApp =
+            searchMimeAppsListsInDirectory(configDir, associations, denyList);
+        if (defaultApp.has_value())
+        {
+            return defaultApp;
+        }
+    }
+
+    // data dirs for backwards compatibility
+    for (const auto &dataDir : getXDGDirectories(XDGDirectoryType::Data))
+    {
+        auto appsDir = combinePath(dataDir, "applications");
+        auto defaultApp =
+            searchMimeAppsListsInDirectory(appsDir, associations, denyList);
+        if (defaultApp.has_value())
+        {
+            return defaultApp;
+        }
+    }
+
+    // no mimeapps.list has an explicit default, use the most preferred added
+    // association that exists. We could search here for one we support...
+    if (!associations.empty())
+    {
+        for (const auto &desktopId : associations)
+        {
+            auto desktopFile = XDGDesktopFile::findDesktopFile(desktopId);
+            if (desktopFile.has_value())
+            {
+                return desktopFile;
+            }
+        }
+    }
+
+    // use xdg-settings if installed
+    QProcess xdgSettings;
+    xdgSettings.start("xdg-settings", {"get", "default-web-browser"},
+                      QIODevice::ReadOnly);
+    xdgSettings.waitForFinished(1000);
+    if (xdgSettings.exitStatus() == QProcess::ExitStatus::NormalExit &&
+        xdgSettings.error() == QProcess::UnknownError &&
+        xdgSettings.exitCode() == 0)
+    {
+        return XDGDesktopFile::findDesktopFile(
+            xdgSettings.readAllStandardOutput().trimmed());
+    }
+
+    return {};
+}
+
+QString parseDesktopExecProgram(const QString &execKey)
+{
+    static const QRegularExpression unescapeReservedCharacters(
+        R"(\\(["`$\\]))");
+
+    QString program = execKey;
+
+    // string values in desktop files escape all backslashes. This is an
+    // independent escaping scheme that must be processed first
+    program.replace(u"\\\\"_s, u"\\"_s);
+
+    if (!program.startsWith('"'))
+    {
+        // not quoted, trim after the first space (if any)
+        auto end = program.indexOf(' ');
+        if (end != -1)
+        {
+            program = program.left(end);
+        }
+    }
+    else
+    {
+        // quoted
+        auto endQuote = program.indexOf('"', 1);
+        if (endQuote == -1)
+        {
+            // No end quote found, the returned program might be malformed
+            program = program.mid(1);
+            qCWarning(LOG).noquote().nospace()
+                << "Malformed desktop entry key " << program << ", originally "
+                << execKey << ", you might run into issues";
+        }
+        else
+        {
+            // End quote found
+            program = program.mid(1, endQuote - 1);
+        }
+    }
+
+    // program now contains the first token of the command line.
+    // this is either the program name with an absolute path, or just the program name
+    // denoting it's a relative path. Either will be handled by QProcess cleanly
+    // now, there is a second escaping scheme specific to the
+    // exec key that must be applied.
+    program.replace(unescapeReservedCharacters, "\\1");
+
+    return program;
+}
+
+}  // namespace chatterino
+
+#endif

src/util/XDGHelper.hpp

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "util/XDGDesktopFile.hpp"
+
+#include <QString>
+
+namespace chatterino {
+
+#if defined(Q_OS_UNIX) and !defined(Q_OS_DARWIN)
+
+std::optional<XDGDesktopFile> getDefaultBrowserDesktopFile();
+
+/// Parses the given `execKey` and returns the resulting program name, ignoring all arguments
+///
+/// Parsing is done in accordance to https://specifications.freedesktop.org/desktop-entry-spec/latest/ar01s07.html
+///
+/// Note: We do *NOT* support field codes
+QString parseDesktopExecProgram(const QString &execKey);
+
+#endif
+
+}  // namespace chatterino

tests/CMakeLists.txt

@@ -4,6 +4,7 @@ option(CHATTERINO_TEST_USE_PUBLIC_HTTPBIN "Use public httpbin for testing networ
 
 set(test_SOURCES
     ${CMAKE_CURRENT_LIST_DIR}/src/main.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/resources/test-resources.qrc
     ${CMAKE_CURRENT_LIST_DIR}/src/ChannelChatters.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/AccessGuard.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/NetworkCommon.cpp
@@ -31,6 +32,8 @@ set(test_SOURCES
     ${CMAKE_CURRENT_LIST_DIR}/src/LinkParser.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/InputCompletion.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/Literals.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/XDGDesktopFile.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/XDGHelper.cpp
     # Add your new file above this line!
     )
 
@@ -62,4 +65,9 @@ if(CHATTERINO_TEST_USE_PUBLIC_HTTPBIN)
     target_compile_definitions(${PROJECT_NAME} PRIVATE CHATTERINO_TEST_USE_PUBLIC_HTTPBIN)
 endif()
 
+set_target_properties(${PROJECT_NAME}
+    PROPERTIES
+    AUTORCC ON
+    )
+
 gtest_discover_tests(${PROJECT_NAME})

tests/resources/001-mimeapps.list

@@ -0,0 +1,32 @@
+thisshould=beignored
+# this is a comment
+
+[test]
+foo=bar
+# cool comment 😂 
+zoo=zar
+
+[Default Applications]
+lol=
+x-scheme-handler/http=firefox.desktop
+x-scheme-handler/https=firefox.desktop
+x-scheme-handler/chrome=firefox.desktop
+text/html=firefox.desktop
+application/x-extension-htm=firefox.desktop
+application/x-extension-html=firefox.desktop
+application/x-extension-shtml=firefox.desktop
+application/xhtml+xml=firefox.desktop
+application/x-extension-xhtml=firefox.desktop
+application/x-extension-xht=firefox.desktop
+
+[Added Associations]
+x-scheme-handler/http=firefox.desktop;
+x-scheme-handler/https=firefox.desktop;
+x-scheme-handler/chrome=firefox.desktop;
+text/html=firefox.desktop;
+application/x-extension-htm=firefox.desktop;
+application/x-extension-html=firefox.desktop;
+application/x-extension-shtml=firefox.desktop;
+application/xhtml+xml=firefox.desktop;
+application/x-extension-xhtml=firefox.desktop;
+application/x-extension-xht=firefox.desktop;

tests/resources/test-resources.qrc

@@ -0,0 +1,5 @@
+<RCC>
+  <qresource prefix="/">
+    <file>001-mimeapps.list</file>
+  </qresource>
+</RCC>

tests/src/XDGDesktopFile.cpp

@@ -0,0 +1,19 @@
+#include "util/XDGDesktopFile.hpp"
+
+#include <gtest/gtest.h>
+#include <QDebug>
+
+using namespace chatterino;
+
+TEST(XDGDesktopFile, String)
+{
+    auto desktopFile = XDGDesktopFile(":/001-mimeapps.list");
+    auto entries = desktopFile.getEntries("Default Applications");
+
+    ASSERT_EQ(entries["thisshould"], "");
+
+    ASSERT_EQ(entries["lol"], "");
+    ASSERT_EQ(entries["x-scheme-handler/http"], QString("firefox.desktop"));
+
+    ASSERT_EQ(desktopFile.getEntries("test").size(), 2);
+}

tests/src/XDGHelper.cpp

@@ -0,0 +1,62 @@
+#include "util/XDGHelper.hpp"
+
+#include <gtest/gtest.h>
+#include <QDebug>
+
+using namespace chatterino;
+
+TEST(XDGHelper, ParseDesktopExecProgram)
+{
+    struct TestCase {
+        QString input;
+        QString expectedOutput;
+    };
+
+    std::vector<TestCase> testCases{
+        {
+            // Sanity check: Ensure simple Exec lines aren't made messed with
+            "firefox",
+            "firefox",
+        },
+        {
+            // Simple trim after the first space
+            "/usr/lib/firefox/firefox %u",
+            "/usr/lib/firefox/firefox",
+        },
+        {
+            // Simple unquote
+            "\"/usr/lib/firefox/firefox\"",
+            "/usr/lib/firefox/firefox",
+        },
+        {
+            // Unquote + trim
+            "\"/usr/lib/firefox/firefox\" %u",
+            "/usr/lib/firefox/firefox",
+        },
+        {
+            // Test malformed exec key (only one quote)
+            "\"/usr/lib/firefox/firefox",
+            "/usr/lib/firefox/firefox",
+        },
+        {
+            // Quoted executable name with space
+            "\"/usr/bin/my cool browser\"",
+            "/usr/bin/my cool browser",
+        },
+        {
+            // Executable name with reserved character
+            "/usr/bin/\\$hadowwizardmoneybrowser",
+            "/usr/bin/$hadowwizardmoneybrowser",
+        },
+    };
+
+    for (const auto &test : testCases)
+    {
+        auto output = parseDesktopExecProgram(test.input);
+
+        EXPECT_EQ(output, test.expectedOutput)
+            << "Input '" << test.input.toStdString() << "' failed. Expected '"
+            << test.expectedOutput.toStdString() << "' but got '"
+            << output.toStdString() << "'";
+    }
+}