FltGetContextsEx function (fltkernel.h)
The FltGetContextsEx routine retrieves a minifilter driver's contexts for the objects related to the current operation.
Syntax
NTSTATUS FLTAPI FltGetContextsEx(
[in] PCFLT_RELATED_OBJECTS FltObjects,
[in] FLT_CONTEXT_TYPE DesiredContexts,
[in] SIZE_T ContextsSize,
[out] PFLT_RELATED_CONTEXTS_EX Contexts
);
Parameters
[in] FltObjects
Pointer to a FLT_RELATED_OBJECTS structure containing opaque pointers for the objects related to the current operation. See Remarks for more information.
[in] DesiredContexts
Identifies the types of contexts to retrieve. This parameter can be a bitwise OR of the following values.
| Constant | Value |
|---|---|
| FLT_VOLUME_CONTEXT | 0x0001 |
| FLT_INSTANCE_CONTEXT | 0x0002 |
| FLT_FILE_CONTEXT | 0x0004 |
| FLT_STREAM_CONTEXT | 0x0008 |
| FLT_STREAMHANDLE_CONTEXT | 0x0010 |
| FLT_TRANSACTION_CONTEXT | 0x0020 |
| FLT_SECTION_CONTEXT | 020040 |
| FLT_ALL_CONTEXTS | Bitwise OR of all of the context values |
[in] ContextsSize
The size, in bytes, of the FLT_RELATED_CONTEXTS_EX structure pointed to by Contexts. Set to sizeof(FLT_RELATED_CONTEXTS_EX).
[out] Contexts
Pointer to a caller-allocated FLT_RELATED_CONTEXTS structure that receives the requested contexts. This parameter is required and cannot be set to NULL. FltMgr sets a structure member to zero for:
- Contexts that the caller did not request.
- Contexts that the caller requested but FltMgr couldn't find.
Return value
FltGetContextsEx returns STATUS_SUCCESS upon successful completion. Otherwise, it returns a status code such as one of the following.
| Code | Meaning |
|---|---|
| STATUS_INVALID_PARAMETER | An invalid context value was input. |
Remarks
For more information about contexts, see About minifilter contexts.
A minifilter driver calls FltGetContextsEx to retrieve pointers to its contexts for the objects in a FLT_RELATED_OBJECTS structure. On STATUS_SUCCESS, the minifilter will need to check that a context is not zero before using it.
The following minifilter driver callback routine types receive a pointer to a FLT_RELATED_OBJECTS structure as the FltObjects input parameter:
- PFLT_PRE_OPERATION_CALLBACK
- PFLT_POST_OPERATION_CALLBACK
- PFLT_INSTANCE_SETUP_CALLBACK
- PFLT_INSTANCE_QUERY_TEARDOWN_CALLBACK
- PFLT_INSTANCE_TEARDOWN_CALLBACK
FltGetContextsEx increments the reference count on each of the contexts returned in the FLT_RELATED_CONTEXTS_EX structure that the Contexts parameter points to. Thus for every successful call to FltGetContextsEx, the caller must either:
- Call FltReleaseContextsEx for the entire structure that the Contexts parameter points to.
- Call FltReleaseContext for each of the contexts returned in the structure and set each context field returned in the structure to zero.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 8 |
| Target Platform | Universal |
| Header | fltkernel.h (include Fltkernel.h) |
| Library | FltMgr.lib |
| DLL | Fltmgr.sys |
| IRQL | <= APC_LEVEL |
See also
PFLT_INSTANCE_QUERY_TEARDOWN_CALLBACK