Meta stuff is terrible.

Penumbra/Meta/MetaFileManager.cs

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+using System;
+using System.Runtime.CompilerServices;
+using Dalamud.Data;
+using Dalamud.Utility.Signatures;
+using FFXIVClientStructs.FFXIV.Client.System.Memory;
+using Penumbra.Collections;
+using Penumbra.Collections.Manager;
+using Penumbra.GameData;
+using Penumbra.Interop.Services;
+using Penumbra.Interop.Structs;
+using Penumbra.Meta.Files;
+using ResidentResourceManager = Penumbra.Interop.Services.ResidentResourceManager;
+
+namespace Penumbra.Meta;
+
+public unsafe class MetaFileManager
+{
+    internal readonly Configuration           Config;
+    internal readonly CharacterUtility        CharacterUtility;
+    internal readonly ResidentResourceManager ResidentResources;
+    internal readonly DataManager             GameData;
+    internal readonly ActiveCollections       ActiveCollections;
+    internal readonly ValidityChecker         ValidityChecker;
+
+    public MetaFileManager(CharacterUtility characterUtility, ResidentResourceManager residentResources, DataManager gameData,
+        ActiveCollections activeCollections, Configuration config, ValidityChecker validityChecker)
+    {
+        CharacterUtility  = characterUtility;
+        ResidentResources = residentResources;
+        GameData          = gameData;
+        ActiveCollections = activeCollections;
+        Config            = config;
+        ValidityChecker   = validityChecker;
+        SignatureHelper.Initialise(this);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
+    public void SetFile(MetaBaseFile? file, MetaIndex metaIndex)
+    {
+        if (file == null)
+            CharacterUtility.ResetResource(metaIndex);
+        else
+            CharacterUtility.SetResource(metaIndex, (nint)file.Data, file.Length);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
+    public CharacterUtility.MetaList.MetaReverter TemporarilySetFile(MetaBaseFile? file, MetaIndex metaIndex)
+        => file == null
+            ? CharacterUtility.TemporarilyResetResource(metaIndex)
+            : CharacterUtility.TemporarilySetResource(metaIndex, (nint)file.Data, file.Length);
+
+    public void ApplyDefaultFiles(ModCollection collection)
+    {
+        if (ActiveCollections.Default != collection || !CharacterUtility.Ready || !Config.EnableMods)
+            return;
+
+        ResidentResources.Reload();
+        collection._cache?.MetaManipulations.SetFiles();
+    }
+
+    /// <summary>
+    /// Allocate in the games space for file storage.
+    /// We only need this if using any meta file.
+    /// </summary>
+    [Signature(Sigs.GetFileSpace)]
+    private readonly nint _getFileSpaceAddress = nint.Zero;
+
+    public IMemorySpace* GetFileSpace()
+        => ((delegate* unmanaged<IMemorySpace*>)_getFileSpaceAddress)();
+
+    public void* AllocateFileMemory(ulong length, ulong alignment = 0)
+        => GetFileSpace()->Malloc(length, alignment);
+
+    public void* AllocateFileMemory(int length, int alignment = 0)
+        => AllocateFileMemory((ulong)length, (ulong)alignment);
+
+    public void* AllocateDefaultMemory(ulong length, ulong alignment = 0)
+        => GetFileSpace()->Malloc(length, alignment);
+
+    public void* AllocateDefaultMemory(int length, int alignment = 0)
+        => IMemorySpace.GetDefaultSpace()->Malloc((ulong)length, (ulong)alignment);
+
+    public void Free(nint ptr, int length)
+        => IMemorySpace.Free((void*)ptr, (ulong)length);
+}