Moved getPathNameInLocal8bit inside FileSystem namespace

Signed-off-by: Trial97 <alexandru.tripon97@gmail.com>

launcher/FileSystem.cpp

@@ -1585,4 +1585,44 @@ uintmax_t hardLinkCount(const QString& path)
     return count;
 }
 
+#ifdef Q_OS_WIN
+// returns 8.3 file format from long path
+QString shortPathName(const QString& file)
+{
+    auto input = file.toStdWString();
+    std::wstring output;
+    long length = GetShortPathNameW(input.c_str(), NULL, 0);
+    if (length == 0)
+        return {};
+    // NOTE: this resizing might seem weird...
+    // when GetShortPathNameW fails, it returns length including null character
+    // when it succeeds, it returns length excluding null character
+    // See: https://msdn.microsoft.com/en-us/library/windows/desktop/aa364989(v=vs.85).aspx
+    output.resize(length);
+    if (GetShortPathNameW(input.c_str(), (LPWSTR)output.c_str(), length) == 0)
+        return {};
+    output.resize(length - 1);
+    QString ret = QString::fromStdWString(output);
+    return ret;
+}
+
+// if the string survives roundtrip through local 8bit encoding...
+bool fitsInLocal8bit(const QString& string)
+{
+    return string == QString::fromLocal8Bit(string.toLocal8Bit());
+}
+
+QString getPathNameInLocal8bit(const QString& file)
+{
+    if (!fitsInLocal8bit(file)) {
+        auto path = shortPathName(file);
+        if (!path.isEmpty()) {
+            return path;
+        }
+        // in case shortPathName fails just return the path as is
+    }
+    return file;
+}
+#endif
+
 }  // namespace FS