Userland/Libraries: Add LibUSBDB library

Simple clone of LibPCIDB to support USB IDs instead of PCI
ones. The format is basically identical, besides a few changes
of the double tab fields.

Userland/Libraries/LibUSBDB/Database.h

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/HashMap.h>
+#include <AK/MappedFile.h>
+#include <AK/NonnullOwnPtr.h>
+#include <AK/RefCounted.h>
+#include <AK/RefPtr.h>
+#include <AK/String.h>
+#include <AK/StringView.h>
+
+namespace USBDB {
+
+struct Interface {
+    u16 interface;
+    StringView name;
+};
+
+struct Device {
+    u16 id;
+    StringView name;
+    HashMap<int, NonnullOwnPtr<Interface>> interfaces;
+};
+
+struct Vendor {
+    u16 id;
+    StringView name;
+    HashMap<int, NonnullOwnPtr<Device>> devices;
+};
+
+struct Protocol {
+    u8 id { 0 };
+    StringView name {};
+};
+
+struct Subclass {
+    u8 id { 0 };
+    StringView name {};
+    HashMap<int, NonnullOwnPtr<Protocol>> protocols;
+};
+
+struct Class {
+    u8 id { 0 };
+    StringView name {};
+    HashMap<int, NonnullOwnPtr<Subclass>> subclasses;
+};
+
+class Database : public RefCounted<Database> {
+public:
+    static RefPtr<Database> open(const String& filename);
+    static RefPtr<Database> open() { return open("/res/usb.ids"); };
+
+    const StringView get_vendor(u16 vendor_id) const;
+    const StringView get_device(u16 vendor_id, u16 device_id) const;
+    const StringView get_interface(u16 vendor_id, u16 device_id, u16 interface_id) const;
+    const StringView get_class(u8 class_id) const;
+    const StringView get_subclass(u8 class_id, u8 subclass_id) const;
+    const StringView get_protocol(u8 class_id, u8 subclass_id, u8 protocol_id) const;
+
+private:
+    explicit Database(NonnullRefPtr<MappedFile> file)
+        : m_file(move(file))
+    {
+    }
+
+    int init();
+
+    enum ParseMode {
+        UnknownMode,
+        VendorMode,
+        ClassMode,
+    };
+
+    NonnullRefPtr<MappedFile> m_file;
+    StringView m_view {};
+    HashMap<int, NonnullOwnPtr<Vendor>> m_vendors;
+    HashMap<int, NonnullOwnPtr<Class>> m_classes;
+    bool m_ready { false };
+};
+
+}