Kernel: Split the ISO9660FileSystem.{cpp,h} files to smaller components

Kernel/FileSystem/ISO9660FS/DirectoryIterator.h

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+#include <Kernel/FileSystem/ISO9660FS/Definitions.h>
+#include <Kernel/FileSystem/ISO9660FS/DirectoryEntry.h>
+#include <Kernel/FileSystem/ISO9660FS/FileSystem.h>
+#include <Kernel/KBuffer.h>
+
+namespace Kernel {
+
+class ISO9660DirectoryIterator {
+public:
+    ISO9660DirectoryIterator(ISO9660FS& fs, ISO::DirectoryRecordHeader const& header);
+
+    ISO::DirectoryRecordHeader const* operator*() { return m_current_header; }
+
+    // Recurses into subdirectories. May fail.
+    ErrorOr<bool> next();
+
+    // Skips to the directory in the list, returns whether there was a next one.
+    // No allocation here, cannot fail.
+    bool skip();
+
+    bool go_up();
+    bool done() const;
+
+private:
+    ErrorOr<void> read_directory_contents();
+
+    void get_header();
+
+    ISO9660FS& m_fs;
+
+    ISO9660FSDirectoryState m_current_directory;
+    ISO::DirectoryRecordHeader const* m_current_header { nullptr };
+
+    Vector<ISO9660FSDirectoryState> m_directory_stack;
+};
+
+}