Redone handling of windows compactor handling.

LightlessSync/FileCache/FileCompactor.cs

@@ -372,6 +372,22 @@ public sealed class FileCompactor : IDisposable
         return _clusterSizes[root];
     }
 
+    public static bool UseSafeHandle(SafeHandle handle, Func<IntPtr, bool> action)
+    {
+        bool addedRef = false;
+        try
+        {
+            handle.DangerousAddRef(ref addedRef);
+            IntPtr ptr = handle.DangerousGetHandle();
+            return action(ptr);
+        }
+        finally
+        {
+            if (addedRef)
+                handle.DangerousRelease();
+        }
+    }
+
     private static bool IsWOFCompactedFile(string filePath)
     {
         uint buf = 8;
@@ -424,22 +440,25 @@ public sealed class FileCompactor : IDisposable
         ulong length = (ulong)Marshal.SizeOf(_efInfo);
         try
         {
-            using var fs = new FileStream(path, FileMode.Open);
+            using var fs = new FileStream(path, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
-            #pragma warning disable S3869 // "SafeHandle.DangerousGetHandle" should not be called
+            var handle = fs.SafeFileHandle;
-            var hFile = fs.SafeFileHandle.DangerousGetHandle();
+
-            #pragma warning restore S3869 // "SafeHandle.DangerousGetHandle" should not be called
+            if (handle.IsInvalid)
-            if (fs.SafeFileHandle.IsInvalid)
             {
                 _logger.LogWarning("Invalid file handle to {file}", path);
                 return false;
             }
 
-            var ret = WofSetFileDataLocation(hFile, WOF_PROVIDER_FILE, efInfoPtr, length);
+            return UseSafeHandle(handle, hFile =>
-            if (!(ret == 0 || ret == unchecked((int)0x80070158)))
             {
-                _logger.LogWarning("Failed to compact {file}: {ret}", path, ret.ToString("X"));
+                int ret = WofSetFileDataLocation(hFile, WOF_PROVIDER_FILE, efInfoPtr, length);
-                return false;
+                if (ret != 0 && ret != unchecked((int)0x80070158))
-            }
+                {
+                    _logger.LogWarning("Failed to compact {file}: {ret}", path, ret.ToString("X"));
+                    return false;
+                }
+                return true;
+            });
         }
         catch (Exception ex)
         {
@@ -450,7 +469,6 @@ public sealed class FileCompactor : IDisposable
         {
             Marshal.FreeHGlobal(efInfoPtr);
         }
-        return true;
     }
 
     private bool BtrfsCompressFile(string path)