dll: FspFileSystemStopServiceIfNecessary

inc/winfsp/winfsp.h

@@ -1047,6 +1047,41 @@ typedef struct _FSP_FILE_SYSTEM_INTERFACE
 
     NTSTATUS (*Obsolete0)(VOID);
 
+    /**
+     * Inform the file system that its dispatcher has been stopped.
+     *
+     * Prior to WinFsp v2.0 the FSD would never unmount a file system volume unless
+     * the user mode file system requested the unmount. Since WinFsp v2.0 it is possible
+     * for the FSD to unmount a file system volume without an explicit user mode file system
+     * request. For example, this happens when the FSD is being uninstalled.
+     *
+     * A user mode file system can use this operation to determine when its dispatcher
+     * has been stopped. The Normally parameter can be used to determine why the dispatcher
+     * was stopped: it is TRUE when the file system is being stopped via
+     * FspFileSystemStopDispatcher and FALSE otherwise.
+     *
+     * When the file system receives a request with Normally == TRUE it need not take any
+     * extra steps. This case is the same as for pre-v2.0 versions: since the file system
+     * stopped the dispatcher via FspFileSystemStopDispatcher, it will likely exit its
+     * process soon.
+     *
+     * When the file system receives a request with Normally == FALSE it may need to take
+     * extra steps to exit its process as this is not done by default.
+     *
+     * A file system that uses the FspService infrastructure may use the
+     * FspFileSystemStopServiceIfNecessary API to correctly handle all cases.
+     *
+     * This operation is the last one that a file system will receive.
+     *
+     * @param FileSystem
+     *     The file system on which this request is posted.
+     * @param Normally
+     *     TRUE if the file system is being stopped via FspFileSystemStopDispatcher.
+     *     FALSE if the file system is being stopped because of another reason such
+     *     as driver unload/uninstall.
+     * @see
+     *     FspFileSystemStopServiceIfNecessary
+     */
     VOID (*DispatcherStopped)(FSP_FILE_SYSTEM *FileSystem,
         BOOLEAN Normally);
 
@@ -1112,7 +1147,7 @@ FSP_API NTSTATUS FspFileSystemPreflight(PWSTR DevicePath,
  * @param VolumeParams
  *     Volume parameters for the newly created file system.
  * @param Interface
- *     A pointer to the actual operations that actually implement this user mode file system.
+ *     A pointer to the operations that implement this user mode file system.
  * @param PFileSystem [out]
  *     Pointer that will receive the file system object created on successful return from this
  *     call.
@@ -1750,6 +1785,23 @@ UINT32 FspFileSystemGetEaPackedSize(PFILE_FULL_EA_INFORMATION SingleEa)
  */
 FSP_API BOOLEAN FspFileSystemAddNotifyInfo(FSP_FSCTL_NOTIFY_INFO *NotifyInfo,
     PVOID Buffer, ULONG Length, PULONG PBytesTransferred);
+/**
+ * Stop a file system service, if any.
+ *
+ * This is a helper for implementing the DispatcherStopped operation, but only for file systems
+ * that use the FspService infrastructure.
+ *
+ * @param FileSystem
+ *     The file system object.
+ * @param Normally
+ *     TRUE if the file system is being stopped via FspFileSystemStopDispatcher.
+ *     FALSE if the file system is being stopped because of another reason such
+ *     as driver unload/uninstall.
+ * @see
+ *     DispatcherStopped
+ */
+FSP_API VOID FspFileSystemStopServiceIfNecessary(FSP_FILE_SYSTEM *FileSystem,
+    BOOLEAN Normally);
 
 /*
  * Directory buffering
@@ -2047,6 +2099,8 @@ FSP_API ULONG FspServiceGetExitCode(FSP_SERVICE *Service);
  * to connect the service process to the Service Control Manager. If the Service Control Manager is
  * not available (and console mode is allowed) it will enter console mode.
  *
+ * This function should be called once per process.
+ *
  * @param Service
  *     The service object.
  * @return

src/dll/fsop.c

@@ -1883,3 +1883,12 @@ FSP_API BOOLEAN FspFileSystemAddNotifyInfo(FSP_FSCTL_NOTIFY_INFO *NotifyInfo,
 {
     return FspFileSystemAddXxxInfo(NotifyInfo, Buffer, Length, PBytesTransferred);
 }
+
+FSP_API VOID FspFileSystemStopServiceIfNecessary(FSP_FILE_SYSTEM *FileSystem,
+    BOOLEAN Normally)
+{
+    /* NOTE: .NET calls us with a zero FileSystem pointer! */
+    if (Normally)
+        return;
+    FspServiceStopLoop();
+}

src/dll/fuse/fuse_intf.c

@@ -2635,6 +2635,17 @@ static NTSTATUS fsp_fuse_intf_SetEa(FSP_FILE_SYSTEM *FileSystem,
         &Uid, &Gid, &Mode, FileInfo);
 }
 
+static VOID fsp_fuse_intf_DispatcherStopped(FSP_FILE_SYSTEM *FileSystem,
+    BOOLEAN Normally)
+{
+    if (Normally)
+        return;
+
+    struct fuse *f = FileSystem->UserContext;
+
+    fsp_fuse_exit(f->env, f);
+}
+
 FSP_FILE_SYSTEM_INTERFACE fsp_fuse_intf =
 {
     fsp_fuse_intf_GetVolumeInfo,
@@ -2668,6 +2679,8 @@ FSP_FILE_SYSTEM_INTERFACE fsp_fuse_intf =
     fsp_fuse_intf_Overwrite,
     fsp_fuse_intf_GetEa,
     fsp_fuse_intf_SetEa,
+    0,
+    fsp_fuse_intf_DispatcherStopped,
 };
 
 /*

src/dll/library.h

@@ -110,6 +110,7 @@ NTSTATUS FspGetModuleFileName(
 VOID FspFileSystemPeekInDirectoryBuffer(PVOID *PDirBuffer,
     PUINT8 *PBuffer, PULONG *PIndex, PULONG PCount);
 
+VOID FspServiceStopLoop(VOID);
 BOOL WINAPI FspServiceConsoleCtrlHandler(DWORD CtrlType);
 
 static inline ULONG FspPathSuffixIndex(PWSTR FileName)

src/dll/service.c

@@ -40,6 +40,8 @@ enum
     GetStatus_WaitHint                  = 0x4000,
 };
 
+static SRWLOCK FspServiceLoopLock = SRWLOCK_INIT;
+static SRWLOCK FspServiceTableLock = SRWLOCK_INIT;
 static SERVICE_TABLE_ENTRYW *FspServiceTable;
 static HANDLE FspServiceConsoleModeEvent;
 static UINT32 FspServiceConsoleCtrlHandlerDisabled;
@@ -220,6 +222,14 @@ FSP_API ULONG FspServiceGetExitCode(FSP_SERVICE *Service)
 
 FSP_API NTSTATUS FspServiceLoop(FSP_SERVICE *Service)
 {
+    /*
+     * FspServiceLoop can only be called once per process, because of StartServiceCtrlDispatcherW
+     * (which returns ERROR_SERVICE_ALREADY_RUNNING if called more than once). Unfortunately this
+     * limitation was never documented and there may be users of FspServiceLoop out there that call
+     * it more than once per process.
+     */
+    AcquireSRWLockExclusive(&FspServiceLoopLock);
+
     NTSTATUS Result;
     SERVICE_TABLE_ENTRYW ServiceTable[2];
 
@@ -236,7 +246,9 @@ FSP_API NTSTATUS FspServiceLoop(FSP_SERVICE *Service)
     ServiceTable[0].lpServiceProc = FspServiceEntry;
     ServiceTable[1].lpServiceName = 0;
     ServiceTable[1].lpServiceProc = 0;
+    AcquireSRWLockExclusive(&FspServiceTableLock);
     FspServiceTable = ServiceTable;
+    ReleaseSRWLockExclusive(&FspServiceTableLock);
 
     if (!StartServiceCtrlDispatcherW(ServiceTable))
     {
@@ -331,11 +343,42 @@ FSP_API NTSTATUS FspServiceLoop(FSP_SERVICE *Service)
     Result = STATUS_SUCCESS;
 
 exit:
+    AcquireSRWLockExclusive(&FspServiceTableLock);
     FspServiceTable = 0;
+    ReleaseSRWLockExclusive(&FspServiceTableLock);
+
+    ReleaseSRWLockExclusive(&FspServiceLoopLock);
 
     return Result;
 }
 
+static DWORD WINAPI FspServiceStopLoopThread(PVOID Context);
+VOID FspServiceStopLoop(VOID)
+{
+    BOOLEAN HasService;
+    HANDLE Thread;
+
+    AcquireSRWLockShared(&FspServiceTableLock);
+    HasService = 0 != FspServiceFromTable();
+    ReleaseSRWLockShared(&FspServiceTableLock);
+
+    if (HasService)
+    {
+        Thread = CreateThread(0, 0, FspServiceStopLoopThread, 0, 0, 0);
+        if (0 != Thread)
+            CloseHandle(Thread);
+    }
+}
+static DWORD WINAPI FspServiceStopLoopThread(PVOID Context)
+{
+    AcquireSRWLockShared(&FspServiceTableLock);
+    FSP_SERVICE *Service = FspServiceFromTable();
+    if (0 != Service)
+        FspServiceStop(Service);
+    ReleaseSRWLockShared(&FspServiceTableLock);
+    return 0;
+}
+
 FSP_API VOID FspServiceStop(FSP_SERVICE *Service)
 {
     SERVICE_STATUS ServiceStatus;
@@ -393,6 +436,7 @@ static VOID WINAPI FspServiceEntry(DWORD Argc, PWSTR *Argv)
     FSP_SERVICE *Service;
 
     Service = FspServiceFromTable();
+        /* we are subordinate to FspServiceLoop; no need to protect this access with FspServiceTableLock */
     if (0 == Service)
     {
         FspServiceLog(EVENTLOG_ERROR_TYPE,
@@ -501,6 +545,7 @@ static DWORD WINAPI FspServiceConsoleModeThread(PVOID Context)
         ;
 
     Service = FspServiceFromTable();
+        /* we are subordinate to FspServiceLoop; no need to protect this access with FspServiceTableLock */
     if (0 == Service)
         FspServiceLog(EVENTLOG_ERROR_TYPE,
             L"" __FUNCTION__ ": internal error: FspServiceFromTable = 0");

src/dotnet/FileSystemBase.cs

@@ -1188,6 +1188,39 @@ namespace Fsp
         {
             return STATUS_INVALID_DEVICE_REQUEST;
         }
+        /// <summary>
+        /// Inform the file system that its dispatcher has been stopped.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// Prior to WinFsp v2.0 the FSD would never unmount a file system volume unless
+        /// the user mode file system requested the unmount. Since WinFsp v2.0 it is possible
+        /// for the FSD to unmount a file system volume without an explicit user mode file system
+        /// request. For example, this happens when the FSD is being uninstalled.
+        /// </para><para>
+        /// A user mode file system can use this operation to determine when its dispatcher
+        /// has been stopped. The Normally parameter can be used to determine why the dispatcher
+        /// was stopped: it is TRUE when the file system is being stopped normally (i.e. via the
+        /// native FspFileSystemStopDispatcher) and FALSE otherwise.
+        /// </para><para>
+        /// A file system that uses the Service class infrastructure may use the
+        /// StopServiceIfNecessary method to correctly handle all cases. The base implementation
+        /// of this method calls the StopServiceIfNecessary method.
+        /// </para><para>
+        /// This operation is the last one that a file system will receive.
+        /// </para>
+        /// </remarks>
+        /// <param name="Normally">
+        /// TRUE if the file system is being stopped via the native FspFileSystemStopDispatcher.
+        /// FALSE if the file system is being stopped because of another reason such
+        /// as driver unload/uninstall.
+        /// </param>
+        /// <seealso cref="StopServiceIfNecessary"/>
+        public virtual void DispatcherStopped(
+            Boolean Normally)
+        {
+            StopServiceIfNecessary(Normally);
+        }
 
         /* helpers */
         /// <summary>
@@ -1483,6 +1516,10 @@ namespace Fsp
         {
             return FullEaInformation.PackedSize(EaName, EaValue, NeedEa);
         }
+        public void StopServiceIfNecessary(Boolean Normally)
+        {
+            Api.FspFileSystemStopServiceIfNecessary(IntPtr.Zero, Normally);
+        }
     }
 
 }

src/dotnet/FileSystemHost.cs

@@ -1426,6 +1426,21 @@ namespace Fsp
             }
         }
 
+        private static void DispatcherStopped(
+            IntPtr FileSystemPtr,
+            Boolean Normally)
+        {
+            FileSystemBase FileSystem = (FileSystemBase)Api.GetUserContext(FileSystemPtr);
+            try
+            {
+                FileSystem.DispatcherStopped(Normally);
+            }
+            catch (Exception ex)
+            {
+                ExceptionHandler(FileSystem, ex);
+            }
+        }
+
         static FileSystemHost()
         {
             _FileSystemInterface.GetVolumeInfo = GetVolumeInfo;
@@ -1456,6 +1471,7 @@ namespace Fsp
             _FileSystemInterface.SetDelete = SetDelete;
             _FileSystemInterface.GetEa = GetEa;
             _FileSystemInterface.SetEa = SetEa;
+            _FileSystemInterface.DispatcherStopped = DispatcherStopped;
 
             _FileSystemInterfacePtr = Marshal.AllocHGlobal(FileSystemInterface.Size);
             /* Marshal.AllocHGlobal does not zero memory; we must do it ourselves! */

src/dotnet/Interop.cs

@@ -745,6 +745,10 @@ namespace Fsp.Interop
                 out FileInfo FileInfo);
             [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
             internal delegate Int32 Obsolete0();
+            [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+            internal delegate void DispatcherStopped(
+                IntPtr FileSystem,
+                [MarshalAs(UnmanagedType.U1)] Boolean Normally);
         }
 
         internal static int Size = IntPtr.Size * 64;
@@ -781,6 +785,7 @@ namespace Fsp.Interop
         internal Proto.GetEa GetEa;
         internal Proto.SetEa SetEa;
         internal Proto.Obsolete0 Obsolete0;
+        internal Proto.DispatcherStopped DispatcherStopped;
         /* NTSTATUS (*Reserved[33])(); */
     }
 
@@ -907,6 +912,10 @@ namespace Fsp.Interop
                 UInt32 Length,
                 out UInt32 PBytesTransferred);
             [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+            internal delegate void FspFileSystemStopServiceIfNecessary(
+                IntPtr FileSystem,
+                [MarshalAs(UnmanagedType.U1)] Boolean Normally);
+            [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
             [return: MarshalAs(UnmanagedType.U1)]
             internal delegate Boolean FspFileSystemAcquireDirectoryBuffer(
                 ref IntPtr PDirBuffer,
@@ -1048,6 +1057,7 @@ namespace Fsp.Interop
         internal static Proto.FspFileSystemAddStreamInfo _FspFileSystemAddStreamInfo;
         internal static Proto.FspFileSystemAddEa _FspFileSystemAddEa;
         internal static Proto.FspFileSystemAddNotifyInfo _FspFileSystemAddNotifyInfo;
+        internal static Proto.FspFileSystemStopServiceIfNecessary FspFileSystemStopServiceIfNecessary;
         internal static Proto.FspFileSystemAcquireDirectoryBuffer FspFileSystemAcquireDirectoryBuffer;
         internal static Proto.FspFileSystemFillDirectoryBuffer FspFileSystemFillDirectoryBuffer;
         internal static Proto.FspFileSystemReleaseDirectoryBuffer FspFileSystemReleaseDirectoryBuffer;
@@ -1506,6 +1516,7 @@ namespace Fsp.Interop
             _FspFileSystemAddStreamInfo = GetEntryPoint<Proto.FspFileSystemAddStreamInfo>(Module);
             _FspFileSystemAddEa = GetEntryPoint<Proto.FspFileSystemAddEa>(Module);
             _FspFileSystemAddNotifyInfo = GetEntryPoint<Proto.FspFileSystemAddNotifyInfo>(Module);
+            FspFileSystemStopServiceIfNecessary = GetEntryPoint<Proto.FspFileSystemStopServiceIfNecessary>(Module);
             FspFileSystemAcquireDirectoryBuffer = GetEntryPoint<Proto.FspFileSystemAcquireDirectoryBuffer>(Module);
             FspFileSystemFillDirectoryBuffer = GetEntryPoint<Proto.FspFileSystemFillDirectoryBuffer>(Module);
             FspFileSystemReleaseDirectoryBuffer = GetEntryPoint<Proto.FspFileSystemReleaseDirectoryBuffer>(Module);

tst/memfs/memfs.cpp

@@ -2275,10 +2275,10 @@ static NTSTATUS SetEa(FSP_FILE_SYSTEM *FileSystem,
 #endif
 
 #if defined(MEMFS_DISPATCHER_STOPPED)
-static void DispatcherStopped(FSP_FILE_SYSTEM *FileSystem,
+static VOID DispatcherStopped(FSP_FILE_SYSTEM *FileSystem,
     BOOLEAN Normally)
 {
-    //FspDebugLog(__FUNCTION__ ": Normally=%d\n", Normally);
+    FspFileSystemStopServiceIfNecessary(FileSystem, Normally);
 }
 #endif
 

tst/ntptfs/ptfs.c

@@ -1143,6 +1143,12 @@ exit:
     return Result;
 }
 
+static VOID DispatcherStopped(FSP_FILE_SYSTEM *FileSystem,
+    BOOLEAN Normally)
+{
+    FspFileSystemStopServiceIfNecessary(FileSystem, Normally);
+}
+
 static FSP_FILE_SYSTEM_INTERFACE PtfsInterface =
 {
     .GetVolumeInfo = GetVolumeInfo,
@@ -1171,6 +1177,7 @@ static FSP_FILE_SYSTEM_INTERFACE PtfsInterface =
     .GetStreamInfo = GetStreamInfo,
     .GetEa = GetEa,
     .SetEa = SetEa,
+    .DispatcherStopped = DispatcherStopped,
 };
 
 NTSTATUS PtfsCreate(