Add way for content to write arbitrary files into replay.

Robust.Shared/Replays/IReplayRecordingManager.cs

@@ -2,6 +2,7 @@
 using Robust.Shared.Serialization.Markdown.Mapping;
 using System;
 using System.Collections.Generic;
+using System.IO.Compression;
 using System.Threading.Tasks;
 using Robust.Shared.ContentPack;
 using Robust.Shared.GameStates;
@@ -71,8 +72,17 @@ public interface IReplayRecordingManager
     /// This gets invoked whenever a replay recording is stopping. Subscribers can use this to add extra yaml data to the
     /// recording's metadata file.
     /// </summary>
+    /// <seealso cref="RecordingStopped2"/>
     event Action<MappingDataNode> RecordingStopped;
 
+    /// <summary>
+    /// This gets invoked whenever a replay recording is stopping. Subscribers can use this to add extra data to the replay.
+    /// </summary>
+    /// <remarks>
+    /// This is effectively a more powerful version of <see cref="RecordingStopped"/>.
+    /// </remarks>
+    event Action<ReplayRecordingStopped> RecordingStopped2;
+
     /// <summary>
     /// This gets invoked after a replay recording has finished and provides information about where the replay data
     /// was saved. Note that this only means that all write tasks have started, however some of the file tasks may not
@@ -131,6 +141,27 @@ bool TryStartRecording(
     bool IsWriting();
 }
 
+/// <summary>
+/// Event object used by <see cref="IReplayRecordingManager.RecordingStopped2"/>.
+/// Allows modifying metadata and adding more data to replay files.
+/// </summary>
+public sealed class ReplayRecordingStopped
+{
+    /// <summary>
+    /// Mutable metadata that will be saved to the replay's metadata file.
+    /// </summary>
+    public required MappingDataNode Metadata { get; init; }
+
+    /// <summary>
+    /// A writer that allows arbitrary file writing into the replay file.
+    /// </summary>
+    public required IReplayFileWriter Writer { get; init; }
+
+    internal ReplayRecordingStopped()
+    {
+    }
+}
+
 /// <summary>
 /// Event data for <see cref="IReplayRecordingManager.RecordingFinished"/>.
 /// </summary>
@@ -148,6 +179,31 @@ public record ReplayRecordingFinished(IWritableDirProvider Directory, ResPath Pa
 /// <param name="UncompressedSize">The total uncompressed size of the replay data blobs.</param>
 public record struct ReplayRecordingStats(TimeSpan Time, uint Ticks, long Size, long UncompressedSize);
 
+/// <summary>
+/// Allows writing extra files directly into the replay file.
+/// </summary>
+/// <seealso cref="ReplayRecordingStopped"/>
+/// <seealso cref="IReplayRecordingManager.RecordingStopped2"/>
+public interface IReplayFileWriter
+{
+    /// <summary>
+    /// The base directory inside the replay directory you should generally be writing to.
+    /// This is equivalent to <see cref="ReplayConstants.ReplayZipFolder"/>.
+    /// </summary>
+    ResPath BaseReplayPath { get; }
+
+    /// <summary>
+    /// Writes arbitrary data into a file in the replay.
+    /// </summary>
+    /// <param name="path">The file path to write to.</param>
+    /// <param name="bytes">The bytes to write to the file.</param>
+    /// <param name="compressionLevel">How much to compress the file.</param>
+    void WriteBytes(
+        ResPath path,
+        ReadOnlyMemory<byte> bytes,
+        CompressionLevel compressionLevel = CompressionLevel.Optimal);
+}
+
 /// <summary>
 /// Engine-internal functions for <see cref="IReplayRecordingManager"/>.
 /// </summary>

Robust.Shared/Replays/SharedReplayRecordingManager.cs

@@ -49,6 +49,7 @@ internal abstract partial class SharedReplayRecordingManager : IReplayRecordingM
 
     public event Action<MappingDataNode, List<object>>? RecordingStarted;
     public event Action<MappingDataNode>? RecordingStopped;
+    public event Action<ReplayRecordingStopped>? RecordingStopped2;
     public event Action<ReplayRecordingFinished>? RecordingFinished;
 
     private ISawmill _sawmill = default!;
@@ -312,6 +313,7 @@ protected virtual void Reset()
 
         // File stream & compression context is always disposed from the worker task.
         _recState.WriteCommandChannel.Complete();
+        _recState.Done = true;
 
         _recState = null;
     }
@@ -373,6 +375,11 @@ private void WriteFinalMetadata(RecordingState recState)
     {
         var yamlMetadata = new MappingDataNode();
         RecordingStopped?.Invoke(yamlMetadata);
+        RecordingStopped2?.Invoke(new ReplayRecordingStopped
+        {
+            Metadata = yamlMetadata,
+            Writer = new ReplayFileWriter(this, recState)
+        });
         var time = Timing.CurTime - recState.StartTime;
         yamlMetadata[MetaFinalKeyEndTick] = new ValueDataNode(Timing.CurTick.Value.ToString());
         yamlMetadata[MetaFinalKeyDuration] = new ValueDataNode(time.ToString());
@@ -384,6 +391,7 @@ private void WriteFinalMetadata(RecordingState recState)
         // this just overwrites the previous yml with additional data.
         var document = new YamlDocument(yamlMetadata.ToYaml());
         WriteYaml(recState, ReplayZipFolder / FileMetaFinal, document);
+
         UpdateWriteTasks();
         Reset();
 
@@ -492,6 +500,8 @@ private sealed class RecordingState
         public long CompressedSize;
         public long UncompressedSize;
 
+        public bool Done;
+
         public RecordingState(
             ZipArchive zip,
             MemoryStream buffer,
@@ -518,4 +528,23 @@ public RecordingState(
             WriteCommandChannel = writeCommandChannel;
         }
     }
+
+    private sealed class ReplayFileWriter(SharedReplayRecordingManager manager, RecordingState state)
+        : IReplayFileWriter
+    {
+        public ResPath BaseReplayPath => ReplayZipFolder;
+
+        public void WriteBytes(ResPath path, ReadOnlyMemory<byte> bytes, CompressionLevel compressionLevel)
+        {
+            CheckDisposed();
+
+            manager.WriteBytes(state, path, bytes, compressionLevel);
+        }
+
+        private void CheckDisposed()
+        {
+            if (state.Done)
+                throw new ObjectDisposedException(nameof(ReplayFileWriter));
+        }
+    }
 }