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

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

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