Align C# locking with rust

src/lib-csharp/UpdateManager.cs

@@ -458,21 +458,13 @@ namespace Velopack
         /// <summary>
         /// Acquires a globally unique mutex/lock for the current application, to avoid concurrent install/uninstall/update operations.
         /// </summary>
-        protected virtual Mutex AcquireUpdateLock()
+        protected virtual async Task<IDisposable> AcquireUpdateLock()
         {
-            var mutexId = $"velopack-{AppId}";
-            bool created = false;
-            Mutex? mutex = null;
-            try {
-                mutex = new Mutex(false, mutexId, out created);
-            } catch (Exception ex) {
-                Log.Warn(ex, "Unable to acquire global mutex/lock.");
-                created = false;
-            }
-            if (mutex == null || !created) {
-                throw new Exception("Cannot perform this operation while another install/unistall operation is in progress.");
-            }
-            return mutex;
+            var dir = Directory.CreateDirectory(Locator.PackagesDir!);
+            var lockPath = Path.Combine(dir.FullName, ".velopack_lock");
+            var fsLock = new FileLock(lockPath);
+            await fsLock.LockAsync().ConfigureAwait(false);
+            return fsLock;
         }
 
         private static IUpdateSource CreateSimpleSource(string urlOrPath)

src/lib-csharp/Util/FileLock.cs

@@ -0,0 +1,38 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Velopack.Util
+{
+    internal class FileLock : IDisposable
+    {
+        private readonly string _filePath;
+        private FileStream? _fileStream;
+        private bool _locked;
+
+        public FileLock(string path)
+        {
+            _filePath = path;
+        }
+
+        public async Task LockAsync()
+        {
+            if (_locked) {
+                return;
+            }
+
+            await IoUtil.RetryAsync(
+                () => {
+                    _fileStream = new FileStream(_filePath, FileMode.Create, FileAccess.Read, FileShare.None, bufferSize: 1, FileOptions.DeleteOnClose);
+                    _locked = true;
+                    return Task.CompletedTask;
+                });
+        }
+
+        public void Dispose()
+        {
+            Interlocked.Exchange(ref this._fileStream, null)?.Dispose();
+        }
+    }
+}