Added FileLocker to avoid exceptions from cross thread IO operations

RuriLib/Blocks/BlockUtility.cs

@@ -1,5 +1,6 @@
 using RuriLib.Functions.Conditions;
 using RuriLib.Functions.Conversions;
+using RuriLib.Functions.Files;
 using RuriLib.LS;
 using RuriLib.Models;
 using RuriLib.ViewModels;
@@ -604,7 +605,7 @@ namespace RuriLib
 
                     case UtilityGroup.File:
                         var file = ReplaceValues(filePath, data);
-                        ThrowIfNotInCWD(file);
+                        Files.ThrowIfNotInCWD(file);
 
                         switch (fileAction)
                         {
@@ -613,43 +614,55 @@ namespace RuriLib
                                 break;
 
                             case FileAction.Read:
-                                data.Variables.Set(new CVar(variableName, File.ReadAllText(file), isCapture));
+                                lock (FileLocker.GetLock(file))
+                                    data.Variables.Set(new CVar(variableName, File.ReadAllText(file), isCapture));
                                 break;
 
                             case FileAction.ReadLines:
-                                data.Variables.Set(new CVar(variableName, File.ReadAllLines(file).ToList(), isCapture));
+                                lock (FileLocker.GetLock(file))
+                                    data.Variables.Set(new CVar(variableName, File.ReadAllLines(file).ToList(), isCapture));
                                 break;
 
                             case FileAction.Write:
-                                CreatePath(file);
-                                File.WriteAllText(file, replacedInput.Unescape());
+                                Files.CreatePath(file);
+                                lock (FileLocker.GetLock(file))
+                                    File.WriteAllText(file, replacedInput.Unescape());
                                 break;
 
                             case FileAction.WriteLines:
-                                CreatePath(file);
-                                File.WriteAllLines(file, ReplaceValuesRecursive(inputString, data).Select(i => i.Unescape()));
+                                Files.CreatePath(file);
+                                lock (FileLocker.GetLock(file))
+                                    File.WriteAllLines(file, ReplaceValuesRecursive(inputString, data).Select(i => i.Unescape()));
                                 break;
 
                             case FileAction.Append:
-                                File.AppendAllText(file, replacedInput.Unescape());
+                                Files.CreatePath(file);
+                                lock (FileLocker.GetLock(file))
+                                    File.AppendAllText(file, replacedInput.Unescape());
                                 break;
 
                             case FileAction.AppendLines:
-                                File.AppendAllLines(file, ReplaceValuesRecursive(inputString, data).Select(i => i.Unescape()));
+                                Files.CreatePath(file);
+                                lock (FileLocker.GetLock(file))
+                                    File.AppendAllLines(file, ReplaceValuesRecursive(inputString, data).Select(i => i.Unescape()));
                                 break;
 
                             case FileAction.Copy:
                                 var fileCopyLocation = ReplaceValues(inputString, data);
-                                ThrowIfNotInCWD(fileCopyLocation);
-                                CreatePath(fileCopyLocation);
-                                File.Copy(file, fileCopyLocation);
+                                Files.ThrowIfNotInCWD(fileCopyLocation);
+                                Files.CreatePath(fileCopyLocation);
+                                lock (FileLocker.GetLock(file))
+                                    lock (FileLocker.GetLock(fileCopyLocation))
+                                        File.Copy(file, fileCopyLocation);
                                 break;
 
                             case FileAction.Move:
                                 var fileMoveLocation = ReplaceValues(inputString, data);
-                                ThrowIfNotInCWD(fileMoveLocation);
-                                CreatePath(fileMoveLocation);
-                                File.Move(file, fileMoveLocation);
+                                Files.ThrowIfNotInCWD(fileMoveLocation);
+                                Files.CreatePath(fileMoveLocation);
+                                lock (FileLocker.GetLock(file))
+                                    lock (FileLocker.GetLock(fileMoveLocation))
+                                        File.Move(file, fileMoveLocation);
                                 break;
                         }
                         data.Log(new LogEntry($"Executed action {fileAction} on file {file}", isCapture ? Colors.Tomato : Colors.Yellow));
@@ -657,7 +670,7 @@ namespace RuriLib
 
                     case UtilityGroup.Folder:
                         var folder = ReplaceValues(folderPath, data);
-                        ThrowIfNotInCWD(folder);
+                        Files.ThrowIfNotInCWD(folder);
 
                         switch (folderAction)
                         {
@@ -678,21 +691,5 @@ namespace RuriLib
             }
             catch(Exception ex) { data.Log(new LogEntry(ex.Message, Colors.Tomato)); }
         }
-
-        private void ThrowIfNotInCWD(string path)
-        {
-            if (!path.IsSubPathOf(Directory.GetCurrentDirectory()))
-            {
-                throw new UnauthorizedAccessException("For security reasons, you cannot interact with paths outside of the current working directory");
-            }
-        }
-
-        private void CreatePath(string file)
-        {
-            if (!Directory.Exists(Path.GetDirectoryName(file)))
-            {
-                Directory.CreateDirectory(Path.GetDirectoryName(file));
-            }
-        }
     }
 }

RuriLib/FileLocker.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RuriLib
+{
+    /// <summary>
+    /// Singleton class that manages application-wide file locking to avoid cross thread IO operations on the same file.
+    /// </summary>
+    public static class FileLocker
+    {
+        /// <summary>
+        /// Maps file names to lockable objects.
+        /// </summary>
+        public static Hashtable Hashtable = new Hashtable();
+
+        /// <summary>
+        /// Gets a lock by file name or creates one if it doesn't exist.
+        /// </summary>
+        /// <param name="fileName">The name of the file to access</param>
+        /// <returns>An object that can be used in a lock statement.</returns>
+        public static object GetLock(string fileName)
+        {
+            if (!Hashtable.ContainsKey(fileName))
+            {
+                Hashtable.Add(fileName, new object());
+            }
+
+            return Hashtable[fileName];
+        }
+    }
+}

RuriLib/Functions/Files/Files.cs

@@ -94,5 +94,31 @@ namespace RuriLib.Functions.Files
 
             return Regex.Replace(name, invalidRegStr, underscore ? "_" : "");
         }
+
+        /// <summary>
+        /// Throws an UnauthorizedAccessException if the path is not part of the current working directory.
+        /// </summary>
+        /// <param name="path">The absolute or relative path.</param>
+        public static void ThrowIfNotInCWD(string path)
+        {
+            if (!path.IsSubPathOf(Directory.GetCurrentDirectory()))
+            {
+                throw new UnauthorizedAccessException("For security reasons, you cannot interact with paths outside of the current working directory");
+            }
+        }
+
+        /// <summary>
+        /// Creates the folder structure that contains a certain files if it doesn't already exist.
+        /// </summary>
+        /// <param name="file">The absolute or relative path to the file.</param>
+        public static void CreatePath(string file)
+        {
+            var dirName = Path.GetDirectoryName(file);
+
+            if (!string.IsNullOrWhiteSpace(dirName) && !Directory.Exists(dirName))
+            {
+                Directory.CreateDirectory(dirName);
+            }
+        }
     }
 }

RuriLib/RuriLib.csproj

@@ -254,6 +254,7 @@
     <Compile Include="CaptchaServices\RuCaptcha.cs" />
     <Compile Include="CaptchaServices\Service.cs" />
     <Compile Include="Extensions.cs" />
+    <Compile Include="FileLocker.cs" />
     <Compile Include="Functions\Conversion\Conversion.cs" />
     <Compile Include="Functions\Crypto\Crypto.cs" />
     <Compile Include="Functions\Download\Download.cs" />