LibWeb: Correctly initialize Storage objects on the Document

Instead of storing all storage objects in static memory, we now
follow the the spec by lazily creating a unique Storage object
on each document object.

Each Storage object now holds a 'proxy' to the underlying backing
storage. For now, this proxy is simply a reference to the backing
object. In the future, it will need to be some type of interface
object that stores on a SQLite database or similar.

Session storage is now correctly stored / tracked as part of the
TraversableNavigable object.

Local storage is still stored in a static map, but eventually this
should be factored into something that is stored at the user agent
level.

Libraries/LibWeb/StorageAPI/StorageBottle.cpp

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2024-2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/HTML/Scripting/Environments.h>
+#include <LibWeb/HTML/TraversableNavigable.h>
+#include <LibWeb/HTML/Window.h>
+#include <LibWeb/StorageAPI/StorageBottle.h>
+#include <LibWeb/StorageAPI/StorageEndpoint.h>
+#include <LibWeb/StorageAPI/StorageShed.h>
+
+namespace Web::StorageAPI {
+
+StorageBucket::StorageBucket(StorageType type)
+{
+    // 1. Let bucket be null.
+    // 2. If type is "local", then set bucket to a new local storage bucket.
+    // 3. Otherwise:
+    //     1. Assert: type is "session".
+    //     2. Set bucket to a new session storage bucket.
+
+    // 4. For each endpoint of registered storage endpoints whose types contain type, set bucket’s bottle map[endpoint’s identifier] to a new storage bottle whose quota is endpoint’s quota.
+    for (auto const& endpoint : StorageEndpoint::registered_endpoints()) {
+        if (endpoint.type == type)
+            bottle_map.set(endpoint.identifier, StorageBottle::create(endpoint.quota));
+    }
+
+    // 5. Return bucket.
+}
+
+// https://storage.spec.whatwg.org/#obtain-a-storage-bottle-map
+RefPtr<StorageBottle> obtain_a_storage_bottle_map(StorageType type, HTML::EnvironmentSettingsObject& environment, StringView identifier)
+{
+    // 1. Let shed be null.
+    StorageShed* shed = nullptr;
+
+    // 2. If type is "local", then set shed to the user agent’s storage shed.
+    if (type == StorageType::Local) {
+        shed = &user_agent_storage_shed();
+    }
+    // 3. Otherwise:
+    else {
+        // 1. Assert: type is "session".
+        VERIFY(type == StorageType::Session);
+
+        // 2. Set shed to environment’s global object’s associated Document’s node navigable’s traversable navigable’s storage shed.
+        shed = &verify_cast<HTML::Window>(environment.global_object()).associated_document().navigable()->traversable_navigable()->storage_shed();
+    }
+
+    // 4. Let shelf be the result of running obtain a storage shelf, with shed, environment, and type.
+    VERIFY(shed);
+    auto shelf = shed->obtain_a_storage_shelf(environment, type);
+
+    // 5. If shelf is failure, then return failure.
+    if (!shelf.has_value())
+        return {};
+
+    // 6. Let bucket be shelf’s bucket map["default"].
+    auto& bucket = shelf->bucket_map.get("default"sv).value();
+
+    // 7. Let bottle be bucket’s bottle map[identifier].
+    auto bottle = bucket.bottle_map.get(identifier).value();
+
+    // 8. Let proxyMap be a new storage proxy map whose backing map is bottle’s map.
+    // 9. Append proxyMap to bottle’s proxy map reference set.
+    // 10. Return proxyMap.
+    return bottle->proxy();
+}
+
+// https://storage.spec.whatwg.org/#obtain-a-session-storage-bottle-map
+RefPtr<StorageBottle> obtain_a_session_storage_bottle_map(HTML::EnvironmentSettingsObject& environment, StringView identifier)
+{
+    // To obtain a session storage bottle map, given an environment settings object environment and storage identifier identifier,
+    // return the result of running obtain a storage bottle map with "session", environment, and identifier.
+    return obtain_a_storage_bottle_map(StorageType::Session, environment, identifier);
+}
+
+// https://storage.spec.whatwg.org/#obtain-a-local-storage-bottle-map
+RefPtr<StorageBottle> obtain_a_local_storage_bottle_map(HTML::EnvironmentSettingsObject& environment, StringView identifier)
+{
+    // To obtain a local storage bottle map, given an environment settings object environment and storage identifier identifier,
+    // return the result of running obtain a storage bottle map with "local", environment, and identifier.
+    return obtain_a_storage_bottle_map(StorageType::Local, environment, identifier);
+}
+
+}

Libraries/LibWeb/StorageAPI/StorageBottle.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2024-2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/HashMap.h>
+#include <AK/String.h>
+#include <LibWeb/Forward.h>
+#include <LibWeb/StorageAPI/StorageType.h>
+
+namespace Web::StorageAPI {
+
+// https://storage.spec.whatwg.org/#storage-bottle
+struct StorageBottle : public RefCounted<StorageBottle> {
+    static NonnullRefPtr<StorageBottle> create(Optional<u64> quota) { return adopt_ref(*new StorageBottle(quota)); }
+
+    // A storage bottle has a map, which is initially an empty map
+    OrderedHashMap<String, String> map;
+
+    // A storage bottle also has a proxy map reference set, which is initially an empty set
+    NonnullRefPtr<StorageBottle> proxy() { return *this; }
+
+    // A storage bottle also has a quota, which is null or a number representing a conservative estimate of
+    // the total amount of bytes it can hold. Null indicates the lack of a limit.
+    Optional<u64> quota;
+
+private:
+    explicit StorageBottle(Optional<u64> quota_)
+        : quota(quota_)
+    {
+    }
+};
+
+using BottleMap = OrderedHashMap<String, NonnullRefPtr<StorageBottle>>;
+
+// https://storage.spec.whatwg.org/#storage-bucket
+// A storage bucket is a place for storage endpoints to store data.
+struct StorageBucket {
+    explicit StorageBucket(StorageType);
+
+    // A storage bucket has a bottle map of storage identifiers to storage bottles.
+    BottleMap bottle_map;
+};
+
+RefPtr<StorageBottle> obtain_a_session_storage_bottle_map(HTML::EnvironmentSettingsObject&, StringView storage_identifier);
+RefPtr<StorageBottle> obtain_a_local_storage_bottle_map(HTML::EnvironmentSettingsObject&, StringView storage_identifier);
+RefPtr<StorageBottle> obtain_a_storage_bottle_map(StorageType, HTML::EnvironmentSettingsObject&, StringView storage_identifier);
+
+}

Libraries/LibWeb/StorageAPI/StorageEndpoint.cpp

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2024-2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/StorageAPI/StorageEndpoint.h>
+
+namespace Web::StorageAPI {
+
+ReadonlySpan<StorageEndpoint> StorageEndpoint::registered_endpoints()
+{
+    // https://storage.spec.whatwg.org/#registered-storage-endpoints
+    static auto const endpoints = to_array<StorageEndpoint>({
+        { "caches"_string, StorageType::Local, {} },
+        { "indexedDB"_string, StorageType::Local, {} },
+        { "localStorage"_string, StorageType::Local, 5 * MiB },
+        { "serviceWorkerRegistrations"_string, StorageType::Local, {} },
+        { "sessionStorage"_string, StorageType::Session, 5 * MiB },
+    });
+    return endpoints;
+}
+
+}

Libraries/LibWeb/StorageAPI/StorageEndpoint.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2024-2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Array.h>
+#include <AK/Optional.h>
+#include <AK/String.h>
+#include <AK/Types.h>
+#include <LibWeb/StorageAPI/StorageType.h>
+
+namespace Web::StorageAPI {
+
+// https://storage.spec.whatwg.org/#storage-endpoint
+//
+// A storage endpoint is a local or session storage API that uses the infrastructure defined by this
+// standard, most notably storage bottles, to keep track of its storage needs.
+struct StorageEndpoint {
+    // https://storage.spec.whatwg.org/#storage-endpoint-identifier
+    // A storage endpoint has an identifier, which is a storage identifier.
+    String identifier;
+
+    // https://storage.spec.whatwg.org/#storage-endpoint-types
+    // A storage endpoint also has types, which is a set of storage types.
+    // NOTE: We do not implement this as a set as it is not neccessary in the current implementation.
+    StorageType type;
+
+    // https://storage.spec.whatwg.org/#storage-endpoint-quota
+    // A storage endpoint also has a quota, which is null or a number representing a recommended quota (in bytes) for each storage bottle corresponding to this storage endpoint.
+    Optional<u64> quota;
+
+    static ReadonlySpan<StorageEndpoint> registered_endpoints();
+};
+
+}

Libraries/LibWeb/StorageAPI/StorageShed.cpp

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2024-2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/HTML/Scripting/Environments.h>
+#include <LibWeb/StorageAPI/StorageShed.h>
+
+namespace Web::StorageAPI {
+
+// https://storage.spec.whatwg.org/#obtain-a-storage-shelf
+Optional<StorageShelf&> StorageShed::obtain_a_storage_shelf(HTML::EnvironmentSettingsObject const& environment, StorageType type)
+{
+    // 1. Let key be the result of running obtain a storage key with environment.
+    auto key = obtain_a_storage_key(environment);
+
+    // 2. If key is failure, then return failure.
+    if (!key.has_value())
+        return {};
+
+    // 3. If shed[key] does not exist, then set shed[key] to the result of running create a storage shelf with type.
+    // 4. Return shed[key].
+    return m_data.ensure(key.value(), [type] {
+        return StorageShelf { type };
+    });
+}
+
+// https://storage.spec.whatwg.org/#user-agent-storage-shed
+StorageShed& user_agent_storage_shed()
+{
+    // A user agent holds a storage shed, which is a storage shed. A user agent’s storage shed holds all local storage data.
+    // FIXME: Storing this statically in memory is not the correct place or way of doing this!
+    static StorageShed storage_shed;
+    return storage_shed;
+}
+
+}

Libraries/LibWeb/StorageAPI/StorageShed.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2024-2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/HashMap.h>
+#include <LibWeb/Forward.h>
+#include <LibWeb/StorageAPI/StorageKey.h>
+#include <LibWeb/StorageAPI/StorageShelf.h>
+#include <LibWeb/StorageAPI/StorageType.h>
+
+namespace Web::StorageAPI {
+
+// https://storage.spec.whatwg.org/#storage-shed
+// A storage shed is a map of storage keys to storage shelves. It is initially empty.
+class StorageShed {
+public:
+    Optional<StorageShelf&> obtain_a_storage_shelf(HTML::EnvironmentSettingsObject const&, StorageType);
+
+private:
+    OrderedHashMap<StorageKey, StorageShelf> m_data;
+};
+
+StorageShed& user_agent_storage_shed();
+
+}

Libraries/LibWeb/StorageAPI/StorageShelf.cpp

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2024-2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/StorageAPI/StorageShelf.h>
+
+namespace Web::StorageAPI {
+
+// https://storage.spec.whatwg.org/#create-a-storage-shelf
+StorageShelf::StorageShelf(StorageType type)
+{
+    // 1. Let shelf be a new storage shelf.
+    // 2. Set shelf’s bucket map["default"] to the result of running create a storage bucket with type.
+    bucket_map.set("default"_string, StorageBucket { type });
+    // 3. Return shelf.
+}
+
+}

Libraries/LibWeb/StorageAPI/StorageShelf.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2024-2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/HashMap.h>
+#include <AK/String.h>
+#include <LibWeb/Forward.h>
+#include <LibWeb/StorageAPI/StorageBottle.h>
+#include <LibWeb/StorageAPI/StorageType.h>
+
+namespace Web::StorageAPI {
+
+// https://storage.spec.whatwg.org/#storage-shelf
+// A storage shelf exists for each storage key within a storage shed. It holds a bucket map, which is a map of strings to storage buckets.
+using BucketMap = OrderedHashMap<String, StorageBucket>;
+
+struct StorageShelf {
+    explicit StorageShelf(StorageType);
+
+    BucketMap bucket_map;
+};
+
+}

Libraries/LibWeb/StorageAPI/StorageType.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024-2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+namespace Web::StorageAPI {
+
+// https://storage.spec.whatwg.org/#storage-type
+// A storage type is "local" or "session".
+enum class StorageType {
+    Local,
+    Session,
+};
+
+}