Implemented file name shortening

src/Core/SecureFolderFS.Core.Dokany/AppModels/DokanyOptions.cs

@@ -1,8 +1,8 @@
-using SecureFolderFS.Core.FileSystem.AppModels;
+using System;
+using System.Collections.Generic;
+using SecureFolderFS.Core.FileSystem.AppModels;
 using SecureFolderFS.Shared.Extensions;
 using SecureFolderFS.Storage.VirtualFileSystem;
-using System;
-using System.Collections.Generic;
 
 namespace SecureFolderFS.Core.Dokany.AppModels
 {
@@ -36,6 +36,7 @@ public static DokanyOptions ToOptions(IDictionary<string, object> options)
  IsCachingFileNames = (bool?)options.Get(nameof(IsCachingFileNames)) ?? true,
  IsCachingDirectoryIds = (bool?)options.Get(nameof(IsCachingDirectoryIds)) ?? true,
  RecycleBinSize = (long?)options.Get(nameof(RecycleBinSize)) ?? 0L,
+ ShorteningThreshold = (int?)options.Get(nameof(ShorteningThreshold)) ?? 0,
 
  // Dokany specific
  MountPoint = (string?)options.Get(nameof(MountPoint))

src/Core/SecureFolderFS.Core.Dokany/Callbacks/OnDeviceDokany.cs

@@ -90,6 +90,9 @@ public override NtStatus CreateFile(string fileName, FileAccess access, FileShar
  {
  }
 
+ // Materialize sidecar for the new directory name if shortened
+ ciphertextPath = GetCiphertextPathForUse(fileName) ?? ciphertextPath;
+
  // Create directory
  _ = Directory.CreateDirectory(ciphertextPath);
 
@@ -172,6 +175,10 @@ public override NtStatus CreateFile(string fileName, FileAccess access, FileShar
  if (specifics.Options.IsReadOnly && mode.IsWriteFlag())
  throw FileSystemExceptions.FileSystemReadOnly;
 
+ // Materialize sidecar for the new file name if shortened
+ if (mode is FileMode.CreateNew or FileMode.Create or FileMode.OpenOrCreate)
+ ciphertextPath = GetCiphertextPathForUse(fileName) ?? ciphertextPath;
+
  var openAccess = readAccess ? System.IO.FileAccess.Read : System.IO.FileAccess.ReadWrite;
  if (mode == FileMode.CreateNew && readAccess)
  openAccess = System.IO.FileAccess.ReadWrite;
@@ -252,6 +259,11 @@ public override void Cleanup(string fileName, IDokanFileInfo info)
  {
  NativeRecycleBinHelpers.DeleteOrRecycle(ciphertextPath, specifics, StorableType.File);
  }
+
+ // Clean up sidecar after successful delete/recycle
+ NativePathHelpers.DeleteSidecarFile(
+ Path.GetFileName(ciphertextPath),
+ Path.GetDirectoryName(ciphertextPath) ?? string.Empty);
  }
  catch (UnauthorizedAccessException)
  {
@@ -537,7 +549,7 @@ public override NtStatus DeleteDirectory(string fileName, IDokanFileInfo info)
  public override NtStatus MoveFile(string oldName, string newName, bool replace, IDokanFileInfo info)
  {
  var oldCiphertextPath = GetCiphertextPath(oldName);
- var newCiphertextPath = GetCiphertextPath(newName);
+ var newCiphertextPath = GetCiphertextPathForUse(newName);
  var fileNameCombined = $"{oldName} -> {newName}";
 
  if (oldCiphertextPath is null || newCiphertextPath is null)
@@ -564,6 +576,11 @@ public override NtStatus MoveFile(string oldName, string newName, bool replace,
  File.Move(oldCiphertextPath, newCiphertextPath);
  }
 
+ // Clean up old sidecar after successful move
+ NativePathHelpers.DeleteSidecarFile(
+ Path.GetFileName(oldCiphertextPath),
+ Path.GetDirectoryName(oldCiphertextPath) ?? string.Empty);
+
  return Trace(DokanResult.Success, fileNameCombined, info);
  }
  else if (replace)
@@ -579,6 +596,11 @@ public override NtStatus MoveFile(string oldName, string newName, bool replace,
  File.Delete(newCiphertextPath);
  File.Move(oldCiphertextPath, newCiphertextPath);
 
+ // Clean up old sidecar after successful move
+ NativePathHelpers.DeleteSidecarFile(
+ Path.GetFileName(oldCiphertextPath),
+ Path.GetDirectoryName(oldCiphertextPath) ?? string.Empty);
+
  return Trace(DokanResult.Success, fileNameCombined, info);
  }
  else
@@ -824,5 +846,10 @@ public override NtStatus FindStreams(string fileName, out IList<FileInformation>
  {
  return NativePathHelpers.GetCiphertextPath(plaintextName, specifics);
  }
+
+ private string? GetCiphertextPathForUse(string plaintextName)
+ {
+ return NativePathHelpers.GetCiphertextPathForUse(plaintextName, specifics);
+ }
  }
 }

src/Core/SecureFolderFS.Core.FUSE/AppModels/FuseOptions.cs

@@ -61,6 +61,7 @@ public static FuseOptions ToOptions(IDictionary<string, object> options)
  IsCachingFileNames = (bool?)options.Get(nameof(IsCachingFileNames)) ?? true,
  IsCachingDirectoryIds = (bool?)options.Get(nameof(IsCachingDirectoryIds)) ?? true,
  RecycleBinSize = (long?)options.Get(nameof(RecycleBinSize)) ?? 0L,
+ ShorteningThreshold = (int?)options.Get(nameof(ShorteningThreshold)) ?? 0,
 
  // FUSE specific
  MountPoint = (string?)options.Get(nameof(MountPoint)),

src/Core/SecureFolderFS.Core.FUSE/Callbacks/OnDeviceFuse.cs

@@ -1,11 +1,14 @@
+using System.Runtime.CompilerServices;
+using System.Text;
+using OwlCore.Storage;
 using SecureFolderFS.Core.FileSystem;
+using SecureFolderFS.Core.FileSystem.Helpers;
 using SecureFolderFS.Core.FileSystem.Helpers.Paths;
+using SecureFolderFS.Core.FileSystem.Helpers.Paths.Abstract;
 using SecureFolderFS.Core.FileSystem.Helpers.Paths.Native;
+using SecureFolderFS.Core.FileSystem.Helpers.RecycleBin.Native;
 using SecureFolderFS.Core.FUSE.OpenHandles;
 using SecureFolderFS.Core.FUSE.UnsafeNative;
-using System.Runtime.CompilerServices;
-using System.Text;
-using SecureFolderFS.Core.FileSystem.Helpers.Paths.Abstract;
 using Tmds.Fuse;
 using Tmds.Linux;
 using static SecureFolderFS.Core.FUSE.UnsafeNative.UnsafeNativeApis;
@@ -65,7 +68,7 @@ public override unsafe int Create(ReadOnlySpan<byte> path, mode_t mode, ref Fuse
  if (FuseOptions!.IsReadOnly)
  return -EROFS;
 
- var ciphertextPath = GetCiphertextPath(path);
+ var ciphertextPath = GetCiphertextPathForUse(path);
  if (ciphertextPath is null)
  return -ENOENT;
 
@@ -259,7 +262,7 @@ public override unsafe int MkDir(ReadOnlySpan<byte> path, mode_t mode)
  if (FuseOptions!.IsReadOnly)
  return -EROFS;
 
- var ciphertextPath = GetCiphertextPath(path);
+ var ciphertextPath = GetCiphertextPathForUse(path);
  if (ciphertextPath is null)
  return -ENOENT;
 
@@ -410,7 +413,7 @@ public override unsafe int Rename(ReadOnlySpan<byte> path, ReadOnlySpan<byte> ne
  return -EROFS;
 
  var ciphertextPath = GetCiphertextPath(path);
- var newCiphertextPath = GetCiphertextPath(newPath);
+ var newCiphertextPath = GetCiphertextPathForUse(newPath);
  if (ciphertextPath is null || newCiphertextPath is null)
  return -ENOENT;
 
@@ -421,10 +424,15 @@ public override unsafe int Rename(ReadOnlySpan<byte> path, ReadOnlySpan<byte> ne
  return -errno;
  }
 
+ // Clean up old sidecar after successful rename
+ NativePathHelpers.DeleteSidecarFile(
+ Path.GetFileName(ciphertextPath),
+ Path.GetDirectoryName(ciphertextPath) ?? string.Empty);
+
  return 0;
  }
 
- public override unsafe int RmDir(ReadOnlySpan<byte> path)
+ public override int RmDir(ReadOnlySpan<byte> path)
  {
  if (FuseOptions!.IsReadOnly)
  return -EROFS;
@@ -437,17 +445,38 @@ public override unsafe int RmDir(ReadOnlySpan<byte> path)
  return -ENOTEMPTY;
 
  var directoryIdPath = Path.Combine(ciphertextPath, FileSystem.Constants.Names.DIRECTORY_ID_FILENAME);
-
- // Remove DirectoryID
- File.Delete(directoryIdPath);
  specifics.DirectoryIdCache.CacheRemove(directoryIdPath);
 
-fixed (byte *ciphertextPathPtr = Encoding.UTF8.GetBytes(ciphertextPath))
+try
  {
- if (rmdir(ciphertextPathPtr) == -1)
- return -errno;
+ NativeRecycleBinHelpers.DeleteOrRecycle(ciphertextPath, specifics, StorableType.Folder);
+ }
+ catch (FileNotFoundException)
+ {
+ return -ENOENT;
+ }
+ catch (DirectoryNotFoundException)
+ {
+ return -ENOENT;
+ }
+ catch (UnauthorizedAccessException)
+ {
+ return -EACCES;
+ }
+ catch (IOException ioEx) when (ErrorHandlingHelpers.IsDiskFullException(ioEx))
+ {
+ return -ENOSPC;
+ }
+ catch
+ {
+ return -EIO;
  }
 
+ // Clean up sidecar after successful delete/recycle
+ NativePathHelpers.DeleteSidecarFile(
+ Path.GetFileName(ciphertextPath),
+ Path.GetDirectoryName(ciphertextPath) ?? string.Empty);
+
  return 0;
  }
 
@@ -529,7 +558,7 @@ public override int Truncate(ReadOnlySpan<byte> path, ulong length, FuseFileInfo
  /// <remarks>
  /// This method is also responsible for file deletion.
  /// </remarks>
- public override unsafe int Unlink(ReadOnlySpan<byte> path)
+ public override int Unlink(ReadOnlySpan<byte> path)
  {
  if (FuseOptions!.IsReadOnly)
  return -EROFS;
@@ -541,11 +570,35 @@ public override unsafe int Unlink(ReadOnlySpan<byte> path)
  if (Directory.Exists(ciphertextPath))
  return -EISDIR;
 
-fixed (byte *ciphertextPathPtr = Encoding.UTF8.GetBytes(ciphertextPath))
+try
  {
- if (unlink(ciphertextPathPtr) == -1)
- return -errno;
+ NativeRecycleBinHelpers.DeleteOrRecycle(ciphertextPath, specifics, StorableType.File);
+ }
+ catch (FileNotFoundException)
+ {
+ return -ENOENT;
+ }
+ catch (DirectoryNotFoundException)
+ {
+ return -ENOENT;
+ }
+ catch (UnauthorizedAccessException)
+ {
+ return -EACCES;
+ }
+ catch (IOException ioEx) when (ErrorHandlingHelpers.IsDiskFullException(ioEx))
+ {
+ return -ENOSPC;
  }
+ catch
+ {
+ return -EIO;
+ }
+
+ // Clean up sidecar after successful delete/recycle
+ NativePathHelpers.DeleteSidecarFile(
+ Path.GetFileName(ciphertextPath),
+ Path.GetDirectoryName(ciphertextPath) ?? string.Empty);
 
  return 0;
  }
@@ -569,7 +622,7 @@ public override unsafe int UpdateTimestamps(ReadOnlySpan<byte> path, ref timespe
  return -errno;
 
  var result = futimens(*(int*)fd, times);
-UnsafeNativeApis.CloseDir(fd);
+ CloseDir(fd);
 
  if (result == -1)
  return -errno;
@@ -614,12 +667,21 @@ public override int Write(ReadOnlySpan<byte> path, ulong offset, ReadOnlySpan<by
  return buffer.Length;
  }
 
- protected override unsafe string? GetCiphertextPath(ReadOnlySpan<byte> plaintextName)
+ protected override unsafe string? GetCiphertextPath(ReadOnlySpan<byte> nativePlaintextName)
+ {
+ fixed (byte *plaintextNamePtr = nativePlaintextName)
+ {
+ var directoryId = new byte[FileSystem.Constants.DIRECTORY_ID_SIZE];
+ return NativePathHelpers.GetCiphertextPath(Encoding.UTF8.GetString(plaintextNamePtr, nativePlaintextName.Length), specifics, directoryId);
+ }
+ }
+
+ private unsafe string? GetCiphertextPathForUse(ReadOnlySpan<byte> nativePlaintextName)
  {
- fixed (byte *plaintextNamePtr = plaintextName)
+ fixed (byte *plaintextNamePtr = nativePlaintextName)
  {
  var directoryId = new byte[FileSystem.Constants.DIRECTORY_ID_SIZE];
- return NativePathHelpers.GetCiphertextPath(Encoding.UTF8.GetString(plaintextNamePtr, plaintextName.Length), specifics, directoryId);
+ return NativePathHelpers.GetCiphertextPathForUse(Encoding.UTF8.GetString(plaintextNamePtr, nativePlaintextName.Length), specifics, directoryId);
  }
  }
  }

src/Core/SecureFolderFS.Core.FileSystem/Constants.cs

@@ -18,6 +18,8 @@ public static class FileSystem
  public static class Names
  {
  public const string ENCRYPTED_FILE_EXTENSION = ".sffs";
+ public const string SHORTENED_FILE_EXTENSION = ".sffsn";
+ public const string SIDECAR_FILE_EXTENSION = ".sffsi";
  public const string DIRECTORY_ID_FILENAME = "dirid.iv";
  public const string RECYCLE_BIN_NAME = "recycle_bin";
  public const string RECYCLE_BIN_CONFIGURATION_FILENAME = "recycle_bin.cfg";

src/Core/SecureFolderFS.Core.FileSystem/Exceptions/OrphanSidecarException.cs

@@ -0,0 +1,15 @@
+using System;
+
+namespace SecureFolderFS.Core.FileSystem.Exceptions
+{
+ /// <summary>
+ /// Exception thrown when a sidecar file (.sffsi) exists without a matching shortened file (.sffsn).
+ /// </summary>
+ public sealed class OrphanSidecarException : Exception
+ {
+ public OrphanSidecarException(string sidecarName)
+ : base($"Orphan sidecar file has no matching shortened file: {sidecarName}")
+ {
+ }
+ }
+}

src/Core/SecureFolderFS.Core.FileSystem/Helpers/Health/HealthHelpers.Directory.cs

@@ -3,7 +3,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 using OwlCore.Storage;
-using SecureFolderFS.Core.Cryptography;
 using SecureFolderFS.Core.FileSystem.Helpers.Paths;
 using SecureFolderFS.Core.FileSystem.Helpers.Paths.Abstract;
 using SecureFolderFS.Shared.ComponentModel;
@@ -15,10 +14,10 @@ namespace SecureFolderFS.Core.FileSystem.Helpers.Health
 {
  public static partial class HealthHelpers
  {
- public static async Task<IResult> RepairDirectoryAsync(IFolder affected, Security security, CancellationToken cancellationToken)
+ public static async Task<IResult> RepairDirectoryAsync(IFolder affected, FileSystemSpecifics specifics, CancellationToken cancellationToken)
  {
  // Return success if no encryption is used
- if (security.NameCrypt is null)
+ if (specifics.Security.NameCrypt is null)
  return Result.Success;
 
  if (affected is not IRenamableFolder renamableFolder)
@@ -39,9 +38,15 @@ public static async Task<IResult> RepairDirectoryAsync(IFolder affected, Securit
  if (PathHelpers.IsCoreName(item.Name))
  continue;
 
- // Encrypt a new name and rename
- var encryptedName = AbstractPathHelpers.EncryptNewName(item.Name, directoryId, security);
+ // Remember old name for sidecar cleanup
+ var oldName = item.Name;
+
+ // Encrypt a new name (writes sidecar if shortening applies) and rename
+ var encryptedName = await AbstractPathHelpers.EncryptNewNameForUseAsync(item.Name, directoryId, affected, specifics, cancellationToken);
  _ = await renamableFolder.RenameAsync(item, encryptedName, cancellationToken);
+
+ // Clean up old sidecar if the previous name was shortened
+ await AbstractPathHelpers.DeleteSidecarFileAsync(oldName, renamableFolder, cancellationToken);
  }
 
  return Result.Success;