fix: Use Win32 API for network path disk space reporting

- Network paths (UNC paths like \\server\share) showed incorrect disk space (fallback values: 1TB/512GB)
- DriveInfo.GetDrives().Single() failed for network paths causing InvalidOperationException
- Users couldn't see actual disk space for mounted network shares

- Added Win32 API `GetDiskFreeSpaceEx` to NativeMethods.cs
- Implemented 3-tier fallback strategy in Mirror.GetDiskFreeSpace():
  1. Try Win32 API first (supports network paths and all path types)
  2. Fallback to DriveInfo for local drives (changed Single() to FirstOrDefault() for safety)
  3. Last resort: return fallback values (512GB/1TB)

- Win32 API properly handles UNC paths with trailing backslash
- Removed verbose logging to avoid unnecessary I/O overhead
- Simple try-catch fallthrough pattern for clean code flow

- Tested with network paths: correct disk space now displayed
- Tested with local paths: no regression, works as before
- Tested with special folders (System Volume Information, Recycle Bin): handles gracefully

- `dokan-mirror-manager/NativeMethods.cs`: Added GetDiskFreeSpaceEx P/Invoke declaration
- `dokan-mirror-manager/Mirror.cs`: Refactored GetDiskFreeSpace() with Win32 API priority

Author: player-alex

dokan-mirror-manager/Mirror.cs

@@ -662,35 +662,56 @@ public NtStatus UnlockFile(ReadOnlyNativeMemory<char> fileName, long offset, lon
 
     public NtStatus GetDiskFreeSpace(out long freeBytesAvailable, out long totalNumberOfBytes, out long totalNumberOfFreeBytes, ref DokanFileInfo info)
     {
+        // Try Win32 API first (supports network paths and all path types)
         try
         {
-            var dinfo = DriveInfo.GetDrives().Single(di => string.Equals(di.RootDirectory.Name, Path.GetPathRoot(path + "\\"), StringComparison.OrdinalIgnoreCase));
+            // Ensure path has trailing backslash for Win32 API
+            var pathForApi = path.TrimEnd('\\') + "\\";
 
-            freeBytesAvailable = dinfo.TotalFreeSpace;
-            totalNumberOfBytes = dinfo.TotalSize;
-            totalNumberOfFreeBytes = dinfo.AvailableFreeSpace;
+            if (NativeMethods.GetDiskFreeSpaceEx(pathForApi, out ulong free, out ulong total, out ulong totalFree))
+            {
+                freeBytesAvailable = (long)free;
+                totalNumberOfBytes = (long)total;
+                totalNumberOfFreeBytes = (long)totalFree;
 
-            return Trace(nameof(GetDiskFreeSpace), default, info, DokanResult.Success, $"out {freeBytesAvailable}",
-                $"out {totalNumberOfBytes}", $"out {totalNumberOfFreeBytes}");
+                return Trace(nameof(GetDiskFreeSpace), default, info, DokanResult.Success, $"out {freeBytesAvailable}",
+                    $"out {totalNumberOfBytes}", $"out {totalNumberOfFreeBytes}");
+            }
         }
-        catch (Exception ex)
+        catch
         {
-            // Log the actual exception for debugging
-            var logPath = System.IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "diskspace_error.log");
-            try
+            // Win32 API failed, fall through to DriveInfo
+        }
+
+        // Fallback to DriveInfo for local drives
+        try
+        {
+            var rootPath = Path.GetPathRoot(path + "\\");
+            var dinfo = DriveInfo.GetDrives()
+                .FirstOrDefault(di => string.Equals(di.RootDirectory.Name, rootPath, StringComparison.OrdinalIgnoreCase));
+
+            if (dinfo != null && dinfo.IsReady)
             {
-                System.IO.File.AppendAllText(logPath, $"[{DateTime.Now}] GetDiskFreeSpace error for path '{path}':\n{ex.GetType().Name}: {ex.Message}\n{ex.StackTrace}\n\n");
+                freeBytesAvailable = dinfo.TotalFreeSpace;
+                totalNumberOfBytes = dinfo.TotalSize;
+                totalNumberOfFreeBytes = dinfo.AvailableFreeSpace;
+
+                return Trace(nameof(GetDiskFreeSpace), default, info, DokanResult.Success, $"out {freeBytesAvailable}",
+                    $"out {totalNumberOfBytes}", $"out {totalNumberOfFreeBytes}");
             }
-            catch { }
+        }
+        catch
+        {
+            // DriveInfo also failed, fall through to fallback
+        }
 
-            // Return fallback values
-            freeBytesAvailable = 512L * 1024 * 1024 * 1024; // 512 GB
-            totalNumberOfBytes = 1024L * 1024 * 1024 * 1024; // 1 TB
-            totalNumberOfFreeBytes = 512L * 1024 * 1024 * 1024; // 512 GB
+        // Last resort: return fallback values
+        freeBytesAvailable = 512L * 1024 * 1024 * 1024; // 512 GB
+        totalNumberOfBytes = 1024L * 1024 * 1024 * 1024; // 1 TB
+        totalNumberOfFreeBytes = 512L * 1024 * 1024 * 1024; // 512 GB
 
-            return Trace(nameof(GetDiskFreeSpace), default, info, DokanResult.Success, $"out {freeBytesAvailable}",
-                $"out {totalNumberOfBytes}", $"out {totalNumberOfFreeBytes}");
-        }
+        return Trace(nameof(GetDiskFreeSpace), default, info, DokanResult.Success, $"out {freeBytesAvailable}",
+            $"out {totalNumberOfBytes}", $"out {totalNumberOfFreeBytes}");
     }
 
     public NtStatus GetVolumeInformation(NativeMemory<char> volumeLabel, out FileSystemFeatures features,

dokan-mirror-manager/NativeMethods.cs

@@ -71,4 +71,28 @@ public static extern bool DeviceIoControl(
 
     // IOCTL for getting volume info
     public const uint FSCTL_GET_RETRIEVAL_POINTERS = 0x00090073;
+
+    /// <summary>
+    /// Retrieves information about the amount of space that is available on a disk volume,
+    /// which is the total amount of space, the total amount of free space, and the total
+    /// amount of free space available to the user that is associated with the calling thread.
+    /// </summary>
+    /// <param name="lpDirectoryName">A directory on the disk.
+    /// If this parameter is NULL, the function uses the root of the current disk.
+    /// If this parameter is a UNC name, it must include a trailing backslash (for example, "\\MyServer\MyShare\").
+    /// Furthermore, a drive specification must have a trailing backslash (for example, "C:\").</param>
+    /// <param name="lpFreeBytesAvailable">A pointer to a variable that receives the total number of free bytes on a disk
+    /// that are available to the user who is associated with the calling thread.</param>
+    /// <param name="lpTotalNumberOfBytes">A pointer to a variable that receives the total number of bytes on a disk
+    /// that are available to the user who is associated with the calling thread.</param>
+    /// <param name="lpTotalNumberOfFreeBytes">A pointer to a variable that receives the total number of free bytes on a disk.</param>
+    /// <returns>If the function succeeds, the return value is nonzero. If the function fails, the return value is zero (0).</returns>
+    /// <remarks>See <a href="https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getdiskfreespaceexw">GetDiskFreeSpaceEx function (MSDN)</a></remarks>
+    [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
+    [return: MarshalAs(UnmanagedType.Bool)]
+    public static extern bool GetDiskFreeSpaceEx(
+        string lpDirectoryName,
+        out ulong lpFreeBytesAvailable,
+        out ulong lpTotalNumberOfBytes,
+        out ulong lpTotalNumberOfFreeBytes);
 }