UnrealEngineUWP/Engine/Source/Programs/UnrealBuildTool/System/HotReload.cs

// Copyright 1998-2019 Epic Games, Inc. All Rights Reserved.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tools.DotNETCommon;

namespace UnrealBuildTool
{
	/// <summary>
	/// The current hot reload mode
	/// </summary>
	enum HotReloadMode
	{
		Default,
		Disabled,
		FromIDE,
		FromEditor
	}

	/// <summary>
	/// Stores the current hot reload state, tracking temporary files created by previous invocations.
	/// </summary>
	[Serializable]
	class HotReloadState
	{
		/// <summary>
		/// Suffix to use for the next hot reload invocation
		/// </summary>
		public int NextSuffix = 1;

		/// <summary>
		/// Map from original filename in the action graph to hot reload file
		/// </summary>
		public Dictionary<FileReference, FileReference> OriginalFileToHotReloadFile = new Dictionary<FileReference, FileReference>();

		/// <summary>
		/// Set of all temporary files created for hot reload
		/// </summary>
		public HashSet<FileReference> TemporaryFiles = new HashSet<FileReference>();

		/// <summary>
		/// Adds all the actions into the hot reload state, so we can restore the action graph on next iteration
		/// </summary>
		/// <param name="ActionsToExecute">The actions being executed</param>
		/// <param name="OldLocationToNewLocation">Mapping from file from their original location (either a previously hot-reloaded file, or an originally compiled file)</param>
		public void CaptureActions(IEnumerable<Action> ActionsToExecute, Dictionary<FileReference, FileReference> OldLocationToNewLocation)
		{
			// Build a mapping of all file items to their original location
			Dictionary<FileReference, FileReference> HotReloadFileToOriginalFile = new Dictionary<FileReference, FileReference>();
			foreach(KeyValuePair<FileReference, FileReference> Pair in OriginalFileToHotReloadFile)
			{
				HotReloadFileToOriginalFile[Pair.Value] = Pair.Key;
			}
			foreach(KeyValuePair<FileReference, FileReference> Pair in OldLocationToNewLocation)
			{
				FileReference OriginalLocation;
				if(!HotReloadFileToOriginalFile.TryGetValue(Pair.Key, out OriginalLocation))
				{
					OriginalLocation = Pair.Key;
				}
				HotReloadFileToOriginalFile[Pair.Value] = OriginalLocation;
			}

			// Now filter out all the hot reload files and update the state
			foreach(Action Action in ActionsToExecute)
			{
				foreach(FileItem ProducedItem in Action.ProducedItems)
				{
					FileReference OriginalLocation;
					if(HotReloadFileToOriginalFile.TryGetValue(ProducedItem.Location, out OriginalLocation))
					{
						OriginalFileToHotReloadFile[OriginalLocation] = ProducedItem.Location;
						TemporaryFiles.Add(ProducedItem.Location);
					}
				}
			}
		}

		/// <summary>
		/// Gets the location of the hot-reload state file for a particular target
		/// </summary>
		/// <param name="ProjectFile">Project containing the target</param>
		/// <param name="TargetName">Name of the target</param>
		/// <param name="Platform">Platform being built</param>
		/// <param name="Configuration">Configuration being built</param>
		/// <param name="Architecture">Architecture being built</param>
		/// <returns>Location of the hot reload state file</returns>
		public static FileReference GetLocation(FileReference ProjectFile, string TargetName, UnrealTargetPlatform Platform, UnrealTargetConfiguration Configuration, string Architecture)
		{
			DirectoryReference BaseDir = DirectoryReference.FromFile(ProjectFile) ?? UnrealBuildTool.EngineDirectory;
			return FileReference.Combine(BaseDir, UEBuildTarget.GetPlatformIntermediateFolder(Platform, Architecture), TargetName, Configuration.ToString(), "HotReload.state");
		}

		/// <summary>
		/// Read the hot reload state from the given location
		/// </summary>
		/// <param name="Location">Location to read from</param>
		/// <returns>New hot reload state instance</returns>
		public static HotReloadState Load(FileReference Location)
		{
			return BinaryFormatterUtils.Load<HotReloadState>(Location);
		}

		/// <summary>
		/// Writes the state to disk
		/// </summary>
		/// <param name="Location">Location to write to</param>
		public void Save(FileReference Location)
		{
			DirectoryReference.CreateDirectory(Location.Directory);
			BinaryFormatterUtils.Save(Location, this);
		}
	}

	static class HotReload
	{
		/// <summary>
		/// Checks if the editor is currently running and this is a hot-reload
		/// </summary>
		public static bool ShouldDoHotReloadFromIDE(BuildConfiguration BuildConfiguration, TargetDescriptor TargetDesc)
		{
			// Check if Hot-reload is disabled globally for this project
			ConfigHierarchy Hierarchy = ConfigCache.ReadHierarchy(ConfigHierarchyType.Engine, DirectoryReference.FromFile(TargetDesc.ProjectFile), TargetDesc.Platform);
			bool bAllowHotReloadFromIDE;
			if (Hierarchy.TryGetValue("BuildConfiguration", "bAllowHotReloadFromIDE", out bAllowHotReloadFromIDE) && !bAllowHotReloadFromIDE)
			{
				return false;
			}

			if(!BuildConfiguration.bAllowHotReloadFromIDE)
			{
				return false;
			}

			bool bIsRunning = false;

			// @todo ubtmake: Kind of cheating here to figure out if an editor target.  At this point we don't have access to the actual target description, and
			// this code must be able to execute before we create or load module rules DLLs so that hot reload can work with bUseUBTMakefiles
			if (TargetDesc.Name.EndsWith("Editor", StringComparison.OrdinalIgnoreCase))
			{
				string EditorBaseFileName = "UE4Editor";
				if (TargetDesc.Configuration != UnrealTargetConfiguration.Development)
				{
					EditorBaseFileName = String.Format("{0}-{1}-{2}", EditorBaseFileName, TargetDesc.Platform, TargetDesc.Configuration);
				}

				FileReference EditorLocation;
				if (TargetDesc.Platform == UnrealTargetPlatform.Win64)
				{
					EditorLocation = FileReference.Combine(UnrealBuildTool.EngineDirectory, "Binaries", "Win64", String.Format("{0}.exe", EditorBaseFileName));
				}
				else if (TargetDesc.Platform == UnrealTargetPlatform.Mac)
				{
					EditorLocation = FileReference.Combine(UnrealBuildTool.EngineDirectory, "Binaries", "Mac", String.Format("{0}.app/Contents/MacOS/{0}", EditorBaseFileName));
				}
				else if (TargetDesc.Platform == UnrealTargetPlatform.Linux)
				{
					EditorLocation = FileReference.Combine(UnrealBuildTool.EngineDirectory, "Binaries", "Linux", EditorBaseFileName);
				}
				else
				{
					throw new BuildException("Unknown editor filename for this platform");
				}

				using(Timeline.ScopeEvent("Finding editor processes for hot-reload"))
				{
					DirectoryReference EditorRunsDir = DirectoryReference.Combine(UnrealBuildTool.EngineDirectory, "Intermediate", "EditorRuns");
					if (!DirectoryReference.Exists(EditorRunsDir))
					{
						return false;
					}

					if(BuildHostPlatform.Current.Platform == UnrealTargetPlatform.Win64)
					{
						foreach(FileReference EditorInstanceFile in DirectoryReference.EnumerateFiles(EditorRunsDir))
						{
							int ProcessId;
							if(!Int32.TryParse(EditorInstanceFile.GetFileName(), out ProcessId))
							{
								FileReference.Delete(EditorInstanceFile);
								continue;
							}

							Process RunningProcess;
							try
							{
								RunningProcess = Process.GetProcessById(ProcessId);
							}
							catch
							{
								RunningProcess = null;
							}

							if(RunningProcess == null)
							{
								FileReference.Delete(EditorInstanceFile);
								continue;
							}

							if(!bIsRunning && EditorLocation == new FileReference(RunningProcess.MainModule.FileName))
							{
								bIsRunning = true;
							}
						}
					}
					else
					{
						FileInfo[] EditorRunsFiles = new DirectoryInfo(EditorRunsDir.FullName).GetFiles();
						BuildHostPlatform.ProcessInfo[] Processes = BuildHostPlatform.Current.GetProcesses();

						foreach (FileInfo File in EditorRunsFiles)
						{
							int PID;
							BuildHostPlatform.ProcessInfo Proc = null;
							if (!Int32.TryParse(File.Name, out PID) || (Proc = Processes.FirstOrDefault(P => P.PID == PID)) == default(BuildHostPlatform.ProcessInfo))
							{
								// Delete stale files (it may happen if editor crashes).
								File.Delete();
								continue;
							}

							// Don't break here to allow clean-up of other stale files.
							if (!bIsRunning)
							{
								// Otherwise check if the path matches.
								bIsRunning = new FileReference(Proc.Filename) == EditorLocation;
							}
						}
					}
				}
			}
			return bIsRunning;
		}

		/// <summary>
		/// Delete all temporary files created by previous hot reload invocations
		/// </summary>
		/// <param name="HotReloadStateFile">Location of the state file</param>
		public static void DeleteTemporaryFiles(FileReference HotReloadStateFile)
		{
			if(FileReference.Exists(HotReloadStateFile))
			{
				// Try to load the state file. If it fails, we'll just warn and continue.
				HotReloadState State = null;
				try
				{
					State = HotReloadState.Load(HotReloadStateFile);
				}
				catch(Exception Ex)
				{
					Log.TraceWarning("Unable to read hot reload state file: {0}", HotReloadStateFile);
					Log.WriteException(Ex, null);
					return;
				}

				// Delete all the output files
				foreach(FileReference Location in State.TemporaryFiles.OrderBy(x => x.FullName, StringComparer.OrdinalIgnoreCase))
				{
					if(FileReference.Exists(Location))
					{
						try
						{
							FileReference.Delete(Location);
						}
						catch(Exception Ex)
						{
							throw new BuildException(Ex, "Unable to delete hot-reload file: {0}", Location);
						}
						Log.TraceInformation("Deleted hot-reload file: {0}", Location);
					}
				}

				// Delete the state file itself
				try
				{
					FileReference.Delete(HotReloadStateFile);
				}
				catch(Exception Ex)
				{
					throw new BuildException(Ex, "Unable to delete hot-reload state file: {0}", HotReloadStateFile);
				}
			}
		}

		/// <summary>
		/// Apply a saved hot reload state to a makefile
		/// </summary>
		/// <param name="HotReloadState">The hot-reload state</param>
		/// <param name="Makefile">Makefile to apply the state</param>
		public static void ApplyState(HotReloadState HotReloadState, TargetMakefile Makefile)
		{
			// Update the action graph to produce these new files
			HotReload.PatchActionGraph(Makefile.Actions, HotReloadState.OriginalFileToHotReloadFile);

			// Update the module to output file mapping
			foreach(string HotReloadModuleName in Makefile.HotReloadModuleNames)
			{
				FileItem[] ModuleOutputItems = Makefile.ModuleNameToOutputItems[HotReloadModuleName];
				for(int Idx = 0; Idx < ModuleOutputItems.Length; Idx++)
				{
					FileReference NewLocation;
					if(HotReloadState.OriginalFileToHotReloadFile.TryGetValue(ModuleOutputItems[Idx].Location, out NewLocation))
					{
						ModuleOutputItems[Idx] = FileItem.GetItemByFileReference(NewLocation);
					}
				}
			}
		}

		/// <summary>
		/// Replaces a hot reload suffix in a filename.
		/// </summary>
		public static FileReference ReplaceSuffix(FileReference File, int Suffix)
		{
			string FileName = File.GetFileName();

			// Find the end of the target and module name
			int HyphenIdx = FileName.IndexOf('-');
			if (HyphenIdx == -1)
			{
				throw new BuildException("Hot-reloadable files are expected to contain a hyphen, eg. UE4Editor-Core");
			}

			int NameEndIdx = HyphenIdx + 1;
			while(NameEndIdx < FileName.Length && FileName[NameEndIdx] != '.' && FileName[NameEndIdx] != '-')
			{
				NameEndIdx++;
			}

			// Strip any existing suffix
			if(NameEndIdx + 1 < FileName.Length && Char.IsDigit(FileName[NameEndIdx + 1]))
			{
				int SuffixEndIdx = NameEndIdx + 2;
				while(SuffixEndIdx < FileName.Length && Char.IsDigit(FileName[SuffixEndIdx]))
				{
					SuffixEndIdx++;
				}
				if(SuffixEndIdx == FileName.Length || FileName[SuffixEndIdx] == '-' || FileName[SuffixEndIdx] == '.')
				{
					FileName = FileName.Substring(0, NameEndIdx) + FileName.Substring(SuffixEndIdx);
				}
			}

			string NewFileName = String.Format("{0}-{1:D4}{2}", FileName.Substring(0, NameEndIdx), Suffix, FileName.Substring(NameEndIdx));

			return FileReference.Combine(File.Directory, NewFileName);
		}

		/// <summary>
		/// Replaces a base filename within a string. Ensures that the filename is not a substring of another longer string (eg. replacing "Foo" will match "Foo.Bar" but not "FooBar" or "BarFooBar"). 
		/// </summary>
		/// <param name="Text">Text to replace within</param>
		/// <param name="OldFileName">Old filename</param>
		/// <param name="NewFileName">New filename</param>
		/// <returns>Text with file names replaced</returns>
		static string ReplaceBaseFileName(string Text, string OldFileName, string NewFileName)
		{
			int StartIdx = 0;
			for(;;)
			{
				int Idx = Text.IndexOf(OldFileName, StartIdx, StringComparison.OrdinalIgnoreCase);
				if(Idx == -1)
				{
					break;
				}
				else if((Idx == 0 || !IsBaseFileNameCharacter(Text[Idx - 1])) && (Idx + OldFileName.Length == Text.Length || !IsBaseFileNameCharacter(Text[Idx + OldFileName.Length])))
				{
					Text = Text.Substring(0, Idx) + NewFileName + Text.Substring(Idx + OldFileName.Length);
					StartIdx = Idx + NewFileName.Length;
				}
				else
				{
					StartIdx = Idx + 1;
				}
			}
			return Text;
		}

		/// <summary>
		/// Determines if a character should be treated as part of a base filename, when updating strings for hot reload
		/// </summary>
		/// <param name="Character">The character to check</param>
		/// <returns>True if the character is part of a base filename, false otherwise</returns>
		static bool IsBaseFileNameCharacter(char Character)
		{
			return Char.IsLetterOrDigit(Character) || Character == '_';
		}

		/// <summary>
		/// Patch the action graph for hot reloading, mapping files according to the given dictionary.
		/// </summary>
		public static void PatchActionGraph(IEnumerable<Action> Actions, Dictionary<FileReference, FileReference> OriginalFileToHotReloadFile)
		{
			// Gather all of the response files for link actions.  We're going to need to patch 'em up after we figure out new
			// names for all of the output files and import libraries
			List<string> ResponseFilePaths = new List<string>();

			// Same as Response files but for all of the link.sh files for link actions.
			// Only used on BuildHostPlatform Linux
			List<string> LinkScriptFilePaths = new List<string>();

			// Keep a map of the original file names and their new file names, so we can fix up response files after
			Dictionary<string, string> OriginalFileNameAndNewFileNameList_NoExtensions = new Dictionary<string, string>();

			// Finally, we'll keep track of any file items that we had to create counterparts for change file names, so we can fix those up too
			Dictionary<FileItem, FileItem> AffectedOriginalFileItemAndNewFileItemMap = new Dictionary<FileItem, FileItem>();

			foreach (Action Action in Actions.Where((Action) => Action.ActionType == ActionType.Link))
			{
				// Assume that the first produced item (with no extension) is our output file name
				FileReference HotReloadFile;
				if(!OriginalFileToHotReloadFile.TryGetValue(Action.ProducedItems[0].Location, out HotReloadFile))
				{
					continue;
				}

				string OriginalFileNameWithoutExtension = Utils.GetFilenameWithoutAnyExtensions(Action.ProducedItems[0].AbsolutePath);
				string NewFileNameWithoutExtension = Utils.GetFilenameWithoutAnyExtensions(HotReloadFile.FullName);

				// Find the response file in the command line.  We'll need to make a copy of it with our new file name.
				string ResponseFileExtension = ".response";
				int ResponseExtensionIndex = Action.CommandArguments.IndexOf(ResponseFileExtension, StringComparison.InvariantCultureIgnoreCase);
				if (ResponseExtensionIndex != -1)
				{
					int ResponseFilePathIndex = Action.CommandArguments.LastIndexOf("@\"", ResponseExtensionIndex);
					if (ResponseFilePathIndex == -1)
					{
						throw new BuildException("Couldn't find response file path in action's command arguments when hot reloading");
					}

					string OriginalResponseFilePathWithoutExtension = Action.CommandArguments.Substring(ResponseFilePathIndex + 2, (ResponseExtensionIndex - ResponseFilePathIndex) - 2);
					string OriginalResponseFilePath = OriginalResponseFilePathWithoutExtension + ResponseFileExtension;

					string NewResponseFilePath = ReplaceBaseFileName(OriginalResponseFilePath, OriginalFileNameWithoutExtension, NewFileNameWithoutExtension);

					// Copy the old response file to the new path
					if(String.Compare(OriginalResponseFilePath, NewResponseFilePath, StringComparison.OrdinalIgnoreCase) != 0)
					{
						File.Copy(OriginalResponseFilePath, NewResponseFilePath, overwrite: true);
					}

					// Keep track of the new response file name.  We'll have to do some edits afterwards.
					ResponseFilePaths.Add(NewResponseFilePath);
				}

				// Find the *.link.sh file in the command line.  We'll need to make a copy of it with our new file name.
				// Only currently used on Linux
				if (UEBuildPlatform.IsPlatformInGroup(BuildHostPlatform.Current.Platform, UnrealPlatformGroup.Unix))
				{
					string LinkScriptFileExtension = ".link.sh";
					int LinkScriptExtensionIndex = Action.CommandArguments.IndexOf(LinkScriptFileExtension, StringComparison.InvariantCultureIgnoreCase);
					if (LinkScriptExtensionIndex != -1)
					{
						// We expect the script invocation to be quoted
						int LinkScriptFilePathIndex = Action.CommandArguments.LastIndexOf("\"", LinkScriptExtensionIndex);
						if (LinkScriptFilePathIndex == -1)
						{
							throw new BuildException("Couldn't find link script file path in action's command arguments when hot reloading. Is the path quoted?");
						}

						string OriginalLinkScriptFilePathWithoutExtension = Action.CommandArguments.Substring(LinkScriptFilePathIndex + 1, (LinkScriptExtensionIndex - LinkScriptFilePathIndex) - 1);
						string OriginalLinkScriptFilePath = OriginalLinkScriptFilePathWithoutExtension + LinkScriptFileExtension;

						string NewLinkScriptFilePath = ReplaceBaseFileName(OriginalLinkScriptFilePath, OriginalFileNameWithoutExtension, NewFileNameWithoutExtension);

						// Copy the old response file to the new path
						File.Copy(OriginalLinkScriptFilePath, NewLinkScriptFilePath, overwrite: true);

						// Keep track of the new response file name.  We'll have to do some edits afterwards.
						LinkScriptFilePaths.Add(NewLinkScriptFilePath);
					}

					// Update this action's list of prerequisite items too
					for (int ItemIndex = 0; ItemIndex < Action.PrerequisiteItems.Count; ++ItemIndex)
					{
						FileItem OriginalPrerequisiteItem = Action.PrerequisiteItems[ItemIndex];
						string NewPrerequisiteItemFilePath = ReplaceBaseFileName(OriginalPrerequisiteItem.AbsolutePath, OriginalFileNameWithoutExtension, NewFileNameWithoutExtension);

						if (OriginalPrerequisiteItem.AbsolutePath != NewPrerequisiteItemFilePath)
						{
							// OK, the prerequisite item's file name changed so we'll update it to point to our new file
							FileItem NewPrerequisiteItem = FileItem.GetItemByPath(NewPrerequisiteItemFilePath);
							Action.PrerequisiteItems[ItemIndex] = NewPrerequisiteItem;

							// Keep track of it so we can fix up dependencies in a second pass afterwards
							AffectedOriginalFileItemAndNewFileItemMap.Add(OriginalPrerequisiteItem, NewPrerequisiteItem);

							ResponseExtensionIndex = OriginalPrerequisiteItem.AbsolutePath.IndexOf(ResponseFileExtension, StringComparison.InvariantCultureIgnoreCase);
							if (ResponseExtensionIndex != -1)
							{
								string OriginalResponseFilePathWithoutExtension = OriginalPrerequisiteItem.AbsolutePath.Substring(0, ResponseExtensionIndex);
								string OriginalResponseFilePath = OriginalResponseFilePathWithoutExtension + ResponseFileExtension;

								string NewResponseFilePath = ReplaceBaseFileName(OriginalResponseFilePath, OriginalFileNameWithoutExtension, NewFileNameWithoutExtension);

								// Copy the old response file to the new path
								File.Copy(OriginalResponseFilePath, NewResponseFilePath, overwrite: true);

								// Keep track of the new response file name.  We'll have to do some edits afterwards.
								ResponseFilePaths.Add(NewResponseFilePath);
							}
						}
					}
				}

				// Go ahead and replace all occurrences of our file name in the command-line (ignoring extensions)
				Action.CommandArguments = ReplaceBaseFileName(Action.CommandArguments, OriginalFileNameWithoutExtension, NewFileNameWithoutExtension);

				// Update this action's list of produced items too
				for (int ItemIndex = 0; ItemIndex < Action.ProducedItems.Count; ++ItemIndex)
				{
					FileItem OriginalProducedItem = Action.ProducedItems[ItemIndex];

					string NewProducedItemFilePath = ReplaceBaseFileName(OriginalProducedItem.AbsolutePath, OriginalFileNameWithoutExtension, NewFileNameWithoutExtension);
					if (OriginalProducedItem.AbsolutePath != NewProducedItemFilePath)
					{
						// OK, the produced item's file name changed so we'll update it to point to our new file
						FileItem NewProducedItem = FileItem.GetItemByPath(NewProducedItemFilePath);
						Action.ProducedItems[ItemIndex] = NewProducedItem;

						// Keep track of it so we can fix up dependencies in a second pass afterwards
						AffectedOriginalFileItemAndNewFileItemMap.Add(OriginalProducedItem, NewProducedItem);
					}
				}

				// The status description of the item has the file name, so we'll update it too
				Action.StatusDescription = ReplaceBaseFileName(Action.StatusDescription, OriginalFileNameWithoutExtension, NewFileNameWithoutExtension);

				// Keep track of the file names, so we can fix up response files afterwards.
				if(!OriginalFileNameAndNewFileNameList_NoExtensions.ContainsKey(OriginalFileNameWithoutExtension))
				{
					OriginalFileNameAndNewFileNameList_NoExtensions[OriginalFileNameWithoutExtension] = NewFileNameWithoutExtension;
				}
				else if(OriginalFileNameAndNewFileNameList_NoExtensions[OriginalFileNameWithoutExtension] != NewFileNameWithoutExtension)
				{
					throw new BuildException("Unexpected conflict in renaming files; {0} maps to {1} and {2}", OriginalFileNameWithoutExtension, OriginalFileNameAndNewFileNameList_NoExtensions[OriginalFileNameWithoutExtension], NewFileNameWithoutExtension);
				}
			}


			// Do another pass and update any actions that depended on the original file names that we changed
			foreach (Action Action in Actions)
			{
				for (int ItemIndex = 0; ItemIndex < Action.PrerequisiteItems.Count; ++ItemIndex)
				{
					FileItem OriginalFileItem = Action.PrerequisiteItems[ItemIndex];

					FileItem NewFileItem;
					if (AffectedOriginalFileItemAndNewFileItemMap.TryGetValue(OriginalFileItem, out NewFileItem))
					{
						// OK, looks like we need to replace this file item because we've renamed the file
						Action.PrerequisiteItems[ItemIndex] = NewFileItem;
					}
				}
			}


			if (OriginalFileNameAndNewFileNameList_NoExtensions.Count > 0)
			{
				foreach (string ResponseFilePath in ResponseFilePaths)
				{
					// Load the file up
					string FileContents = Utils.ReadAllText(ResponseFilePath);

					// Replace all of the old file names with new ones
					foreach (KeyValuePair<string, string> FileNameTuple in OriginalFileNameAndNewFileNameList_NoExtensions)
					{
						string OriginalFileNameWithoutExtension = FileNameTuple.Key;
						string NewFileNameWithoutExtension = FileNameTuple.Value;

						FileContents = ReplaceBaseFileName(FileContents, OriginalFileNameWithoutExtension, NewFileNameWithoutExtension);
					}

					// Overwrite the original file
					File.WriteAllText(ResponseFilePath, FileContents, new System.Text.UTF8Encoding(false));
				}

				if (UEBuildPlatform.IsPlatformInGroup(BuildHostPlatform.Current.Platform, UnrealPlatformGroup.Unix))
				{
					foreach (string LinkScriptFilePath in LinkScriptFilePaths)
					{
						// Load the file up
						string FileContents = Utils.ReadAllText(LinkScriptFilePath);

						// Replace all of the old file names with new ones
						foreach (KeyValuePair<string, string> FileNameTuple in OriginalFileNameAndNewFileNameList_NoExtensions)
						{
							string OriginalFileNameWithoutExtension = FileNameTuple.Key;
							string NewFileNameWithoutExtension = FileNameTuple.Value;

							FileContents = ReplaceBaseFileName(FileContents, OriginalFileNameWithoutExtension, NewFileNameWithoutExtension);
						}

						// Overwrite the original file
						File.WriteAllText(LinkScriptFilePath, FileContents, new System.Text.UTF8Encoding(false));
					}
				}
			}

			// Update the action that writes out the module manifests
			foreach(Action Action in Actions)
			{
				if(Action.ActionType == ActionType.WriteMetadata)
				{
					string Arguments = Action.CommandArguments;

					// Find the argument for the metadata file
					const string InputArgument = "-Input=";

					int InputIdx = Arguments.IndexOf(InputArgument);
					if(InputIdx == -1)
					{
						throw new Exception("Missing -Input= argument to WriteMetadata command when patching action graph.");
					}

					int FileNameIdx = InputIdx + InputArgument.Length;
					if(Arguments[FileNameIdx] == '\"')
					{
						FileNameIdx++;
					}

					int FileNameEndIdx = FileNameIdx;
					while(FileNameEndIdx < Arguments.Length && (Arguments[FileNameEndIdx] != ' ' || Arguments[FileNameIdx - 1] == '\"') && Arguments[FileNameEndIdx] != '\"')
					{
						FileNameEndIdx++;
					}

					// Read the metadata file
					FileReference TargetInfoFile = new FileReference(Arguments.Substring(FileNameIdx, FileNameEndIdx - FileNameIdx));
					if(!FileReference.Exists(TargetInfoFile))
					{
						throw new Exception(String.Format("Unable to find metadata file to patch action graph ({0})", TargetInfoFile));
					}

					// Update the module names
					WriteMetadataTargetInfo TargetInfo = BinaryFormatterUtils.Load<WriteMetadataTargetInfo>(TargetInfoFile);
					foreach (KeyValuePair<FileReference, ModuleManifest> FileNameToVersionManifest in TargetInfo.FileToManifest)
					{
						foreach (KeyValuePair<string, string> Manifest in FileNameToVersionManifest.Value.ModuleNameToFileName)
						{
							FileReference OriginalFile = FileReference.Combine(FileNameToVersionManifest.Key.Directory, Manifest.Key);

							FileReference HotReloadFile;
							if(OriginalFileToHotReloadFile.TryGetValue(OriginalFile, out HotReloadFile))
							{
								FileNameToVersionManifest.Value.ModuleNameToFileName[Manifest.Key] = HotReloadFile.GetFileName();
								break;
							}
						}
					}

					// Write the hot-reload metadata file and update the argument list
					FileReference HotReloadTargetInfoFile = FileReference.Combine(TargetInfoFile.Directory, "Metadata-HotReload.dat");
					BinaryFormatterUtils.Save(HotReloadTargetInfoFile, TargetInfo);
					Arguments = Arguments.Substring(0, FileNameIdx) + HotReloadTargetInfoFile + Arguments.Substring(FileNameEndIdx);
				}
			}
		}

		/// <summary>
		/// Patches a set of actions to use a specific list of suffixes for each module name
		/// </summary>
		/// <param name="PrerequisiteActions">Actions in the target being built</param>
		/// <param name="ModuleNameToSuffix">Map of module name to suffix</param>
		/// <param name="Makefile">Makefile for the target being built</param>
		public static void PatchActionGraphWithNames(List<Action> PrerequisiteActions, Dictionary<string, int> ModuleNameToSuffix, TargetMakefile Makefile)
		{
			if(ModuleNameToSuffix.Count > 0)
			{
				Dictionary<FileReference, FileReference> OldLocationToNewLocation = new Dictionary<FileReference, FileReference>();
				foreach(string HotReloadModuleName in Makefile.HotReloadModuleNames)
				{
					int ModuleSuffix;
					if(ModuleNameToSuffix.TryGetValue(HotReloadModuleName, out ModuleSuffix))
					{
						FileItem[] ModuleOutputItems = Makefile.ModuleNameToOutputItems[HotReloadModuleName];
						foreach(FileItem ModuleOutputItem in ModuleOutputItems)
						{
							FileReference OldLocation = ModuleOutputItem.Location;
							FileReference NewLocation = HotReload.ReplaceSuffix(OldLocation, ModuleSuffix);
							OldLocationToNewLocation[OldLocation] = NewLocation;
						}
					}
				}
				HotReload.PatchActionGraph(PrerequisiteActions, OldLocationToNewLocation);
			}
		}
	}
}