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dll: FspFileSystemInitialize, FspFileSystemFinalize

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This commit is contained in:
Bill Zissimopoulos 2016-04-08 15:25:09 -07:00
parent 5b917c4566
commit ef5b664dcc
4 changed files with 114 additions and 14 deletions
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1
inc/winfsp/winfsp.h
View File

@ -125,6 +125,7 @@ typedef struct _FSP_FILE_SYSTEM
ULONG DispatcherThreadCount;
NTSTATUS DispatcherResult;
PWSTR MountPoint;
LIST_ENTRY MountEntry;
} FSP_FILE_SYSTEM;
FSP_API NTSTATUS FspFileSystemCreate(PWSTR DevicePath,
const FSP_FSCTL_VOLUME_PARAMS *VolumeParams,

92
src/dll/dispatch.c
View File

@ -13,6 +13,62 @@ enum
static FSP_FILE_SYSTEM_INTERFACE FspFileSystemNullInterface;
static CRITICAL_SECTION FspFileSystemMountListGuard;
static LIST_ENTRY FspFileSystemMountList = { &FspFileSystemMountList, &FspFileSystemMountList };
VOID FspFileSystemInitialize(VOID)
{
/*
* This function is called during DLL_PROCESS_ATTACH. We must therefore keep initialization
* tasks to a minimum.
*
* Initialization of synchronization objects is allowed! See:
* https://msdn.microsoft.com/en-us/library/windows/desktop/dn633971(v=vs.85).aspx
*/
InitializeCriticalSection(&FspFileSystemMountListGuard);
}
VOID FspFileSystemFinalize(VOID)
{
/*
* This function is called during DLL_PROCESS_DETACH. We must therefore keep finalization
* tasks to a minimum.
*
* Very few things can be safely done during DLL_PROCESS_DETACH. See:
* https://msdn.microsoft.com/en-us/library/windows/desktop/dn633971(v=vs.85).aspx
* https://blogs.msdn.microsoft.com/oldnewthing/20070503-00/?p=27003/
* https://blogs.msdn.microsoft.com/oldnewthing/20100122-00/?p=15193/
*
* We enter our FspFileSystemMountListGuard critical section here and then attempt to cleanup
* our mount points using DefineDosDeviceW. On Vista and later orphaned critical sections
* become "electrified", so our process will be forcefully terminated if one of its threads
* was already modifying the list when the ExitProcess happened. This is a good thing!
*
* The use of DefineDosDeviceW is rather suspect and probably unsafe. DefineDosDeviceW reaches
* out to CSRSS, which is probably not the safest thing to do when in DllMain! There is also
* some evidence that it may attempt to load DLL's under some circumstances, which is a
* definite no-no as we are under the loader lock!
*/
FSP_FILE_SYSTEM *FileSystem;
PLIST_ENTRY MountEntry;
EnterCriticalSection(&FspFileSystemMountListGuard);
for (MountEntry = FspFileSystemMountList.Flink;
&FspFileSystemMountList != MountEntry;
MountEntry = MountEntry->Flink)
{
FileSystem = CONTAINING_RECORD(MountEntry, FSP_FILE_SYSTEM, MountEntry);
DefineDosDeviceW(DDD_RAW_TARGET_PATH | DDD_REMOVE_DEFINITION | DDD_EXACT_MATCH_ON_REMOVE,
FileSystem->MountPoint, FileSystem->VolumeName);
}
LeaveCriticalSection(&FspFileSystemMountListGuard);
}
FSP_API NTSTATUS FspFileSystemCreate(PWSTR DevicePath,
const FSP_FSCTL_VOLUME_PARAMS *VolumeParams,
const FSP_FILE_SYSTEM_INTERFACE *Interface,
@ -74,6 +130,8 @@ FSP_API NTSTATUS FspFileSystemSetMountPoint(FSP_FILE_SYSTEM *FileSystem, PWSTR M
if (0 != FileSystem->MountPoint)
return STATUS_INVALID_PARAMETER;
NTSTATUS Result;
if (0 == MountPoint)
{
DWORD Drives;
@ -94,17 +152,14 @@ FSP_API NTSTATUS FspFileSystemSetMountPoint(FSP_FILE_SYSTEM *FileSystem, PWSTR M
MountPoint[0] = Drive;
if (DefineDosDeviceW(DDD_RAW_TARGET_PATH, MountPoint, FileSystem->VolumeName))
{
FileSystem->MountPoint = MountPoint;
return STATUS_SUCCESS;
Result = STATUS_SUCCESS;
goto exit;
}
}
SetLastError(ERROR_FILE_NOT_FOUND);
Result = STATUS_NO_SUCH_DEVICE;
}
MemFree(MountPoint);
return FspNtStatusFromWin32(GetLastError());
else
Result = FspNtStatusFromWin32(GetLastError());
}
else
{
@ -122,15 +177,24 @@ FSP_API NTSTATUS FspFileSystemSetMountPoint(FSP_FILE_SYSTEM *FileSystem, PWSTR M
MountPoint = P;
if (DefineDosDeviceW(DDD_RAW_TARGET_PATH, MountPoint, FileSystem->VolumeName))
Result = STATUS_SUCCESS;
else
Result = FspNtStatusFromWin32(GetLastError());
}
exit:
if (NT_SUCCESS(Result))
{
FileSystem->MountPoint = MountPoint;
return STATUS_SUCCESS;
}
EnterCriticalSection(&FspFileSystemMountListGuard);
InsertTailList(&FspFileSystemMountList, &FileSystem->MountEntry);
LeaveCriticalSection(&FspFileSystemMountListGuard);
}
else
MemFree(MountPoint);
return FspNtStatusFromWin32(GetLastError());
}
return Result;
}
FSP_API VOID FspFileSystemRemoveMountPoint(FSP_FILE_SYSTEM *FileSystem)
@ -138,6 +202,10 @@ FSP_API VOID FspFileSystemRemoveMountPoint(FSP_FILE_SYSTEM *FileSystem)
if (0 == FileSystem->MountPoint)
return;
EnterCriticalSection(&FspFileSystemMountListGuard);
RemoveEntryList(&FileSystem->MountEntry);
LeaveCriticalSection(&FspFileSystemMountListGuard);
DefineDosDeviceW(DDD_RAW_TARGET_PATH | DDD_REMOVE_DEFINITION | DDD_EXACT_MATCH_ON_REMOVE,
FileSystem->MountPoint, FileSystem->VolumeName);

4
src/dll/library.c
View File

@ -16,6 +16,10 @@ BOOL WINAPI DllMain(HINSTANCE Instance, DWORD Reason, PVOID Reserved)
ProcessHeap = GetProcessHeap();
if (0 == ProcessHeap)
return FALSE;
FspFileSystemInitialize();
break;
case DLL_PROCESS_DETACH:
FspFileSystemFinalize();
break;
}

27
src/dll/library.h
View File

@ -68,4 +68,31 @@ void *memset(void *dst, int val, size_t siz)
}
#endif
static FORCEINLINE
VOID InsertTailList(PLIST_ENTRY ListHead, PLIST_ENTRY Entry)
{
PLIST_ENTRY Blink;
Blink = ListHead->Blink;
Entry->Flink = ListHead;
Entry->Blink = Blink;
Blink->Flink = Entry;
ListHead->Blink = Entry;
}
static FORCEINLINE
BOOLEAN RemoveEntryList(PLIST_ENTRY Entry)
{
PLIST_ENTRY Blink;
PLIST_ENTRY Flink;
Flink = Entry->Flink;
Blink = Entry->Blink;
Blink->Flink = Flink;
Flink->Blink = Blink;
return Flink == Blink;
}
VOID FspFileSystemInitialize(VOID);
VOID FspFileSystemFinalize(VOID);
#endif