Prepare filesystem support

src/windows-emulator/file_system.hpp

@@ -0,0 +1,85 @@
+#pragma once
+#include "std_include.hpp"
+#include <utils/path_key.hpp>
+
+class file_system
+{
+  public:
+    static constexpr std::u16string_view nt_prefix = u"\\??\\";
+
+    file_system(std::filesystem::path root, std::u16string working_dir)
+        : root_(std::move(root)),
+          working_dir_(std::move(working_dir))
+    {
+    }
+
+    static std::filesystem::path canonicalize_windows_path(const std::filesystem::path& file)
+    {
+        const auto wide_file = file.u16string();
+
+        if (!wide_file.starts_with(nt_prefix))
+        {
+            return file;
+        }
+
+        return canonicalize_windows_path(wide_file.substr(nt_prefix.size()));
+    }
+
+    static std::filesystem::path canonicalize(const std::filesystem::path& path)
+    {
+        return utils::path_key::canonicalize_path(canonicalize_windows_path(path));
+    }
+
+    static std::filesystem::path canonicalize_drive_letter(const std::filesystem::path& path)
+    {
+        auto canonical_path = canonicalize(path);
+        if (canonical_path.empty() || !path.has_root_path())
+        {
+            return canonical_path;
+        }
+
+        return adapt_drive_component(canonical_path);
+    }
+
+    std::filesystem::path translate(const std::filesystem::path& win_path) const
+    {
+        const auto absolute_win_dir = make_absolute_windows_path(win_path.u16string());
+        return this->root_ / canonicalize_drive_letter(absolute_win_dir);
+    }
+
+    void set_working_directory(std::u16string working_dir)
+    {
+        this->working_dir_ = std::move(working_dir);
+    }
+
+    const std::u16string& get_working_directory() const
+    {
+        return this->working_dir_;
+    }
+
+  private:
+    std::filesystem::path root_;
+    std::u16string working_dir_;
+
+    std::u16string make_absolute_windows_path(const std::u16string& path) const
+    {
+        if (!path.starts_with(nt_prefix) && (path.size() < 2 || path[1] != ':'))
+        {
+            return this->working_dir_ + u'/' + path;
+        }
+
+        return path;
+    }
+
+    static std::filesystem::path adapt_drive_component(const std::filesystem::path& original_path)
+    {
+        auto root_name = original_path.root_name().u16string();
+
+        if (!root_name.empty() && root_name.back() == u':')
+        {
+            root_name.pop_back();
+        }
+
+        return root_name + original_path.root_directory().u16string() + original_path.relative_path().u16string();
+    }
+};