816 lines
20 KiB
C
816 lines
20 KiB
C
/*++
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Copyright (c) 1997 Microsoft Corporation
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Module Name:
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FiltrCtx.c
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Abstract:
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This module provides three routines that allow filesystem filter drivers
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to associate state with FILE_OBJECTs -- for filesystems which support
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an extended FSRTL_COMMON_HEADER with FsContext.
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These routines depend on fields (FastMutext and FilterContexts)
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added at the end of FSRTL_COMMON_HEADER in NT 5.0.
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Filesystems should set FSRTL_FLAG2_SUPPORTS_FILTER_CONTEXTS if
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these new fields are supported. They must also initialize the mutex
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and list head.
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Filter drivers must use a common header for the context they wish to
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associate with a file object:
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FSRTL_FILTER_CONTEXT:
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LIST_ENTRY Links;
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PVOID OwnerId;
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PVOID InstanceId;
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The OwnerId is a bit pattern unique to each filter driver
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(e.g. the device object).
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The InstanceId is used to specify a particular instance of the context
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data owned by a filter driver (e.g. the file object).
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Author:
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Dave Probert [DavePr] 30-May-1997
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Revision History:
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Neal Christiansen [nealch] 12-Jan-2001 Changed APIs to take
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PFSRTL_ADVANCED_FCB_HEADER
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structures instead of
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FileObjects.
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Neal Christiansen [nealch] 19-Jan-2001 Added mutex lock to FsRtlTeardownFilterContexts
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because you can get filters
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trying to delete at the same
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time the file system is trying
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to delete.
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Neal Christiansen [nealch] 25-Apr-2001 Added FileObject context routines
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Neal Christiansen [nealch] 25-Apr-2001 Marked all of this code as pageable
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--*/
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#include "FsRtlP.h"
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#define MySearchList(pHdr, Ptr) \
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for ( Ptr = (pHdr)->Flink; Ptr != (pHdr); Ptr = Ptr->Flink )
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//
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// The rest of the routines are not marked pageable so they can be called
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// during the paging path
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//
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NTKERNELAPI
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VOID
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FsRtlTeardownFilterContexts (
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IN PFSRTL_ADVANCED_FCB_HEADER AdvFcbHeader
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);
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(PAGE, FsRtlTeardownPerStreamContexts)
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#pragma alloc_text(PAGE, FsRtlTeardownFilterContexts)
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#pragma alloc_text(PAGE, FsRtlPTeardownPerFileObjectContexts)
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#endif
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//===========================================================================
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// Handles Stream Contexts
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//===========================================================================
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NTKERNELAPI
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NTSTATUS
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FsRtlInsertPerStreamContext (
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IN PFSRTL_ADVANCED_FCB_HEADER AdvFcbHeader,
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IN PFSRTL_PER_STREAM_CONTEXT Ptr
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)
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/*++
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Routine Description:
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This routine associates filter driver context with a stream.
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Arguments:
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AdvFcbHeader - Advanced FCB Header for stream of interest.
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Ptr - Pointer to the filter-specific context structure.
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The common header fields OwnerId and InstanceId should
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be filled in by the filter driver before calling.
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Return Value:
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STATUS_SUCCESS - operation succeeded.
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STATUS_INVALID_DEVICE_REQUEST - underlying filesystem does not support
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filter contexts.
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--*/
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{
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if (!AdvFcbHeader ||
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!FlagOn(AdvFcbHeader->Flags2,FSRTL_FLAG2_SUPPORTS_FILTER_CONTEXTS))
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{
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return STATUS_INVALID_DEVICE_REQUEST;
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}
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ExAcquireFastMutex(AdvFcbHeader->FastMutex);
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InsertHeadList(&AdvFcbHeader->FilterContexts, &Ptr->Links);
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ExReleaseFastMutex(AdvFcbHeader->FastMutex);
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return STATUS_SUCCESS;
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}
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NTKERNELAPI
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PFSRTL_PER_STREAM_CONTEXT
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FsRtlLookupPerStreamContextInternal (
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IN PFSRTL_ADVANCED_FCB_HEADER AdvFcbHeader,
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IN PVOID OwnerId OPTIONAL,
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IN PVOID InstanceId OPTIONAL
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)
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/*++
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Routine Description:
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This routine lookups filter driver context associated with a stream.
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The macro FsRtlLookupFilterContext should be used instead of calling
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this routine directly. The macro optimizes for the common case
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of an empty list.
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Arguments:
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AdvFcbHeader - Advanced FCB Header for stream of interest.
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OwnerId - Used to identify context information belonging to a particular
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filter driver.
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InstanceId - Used to search for a particular instance of a filter driver
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context. If not provided, any of the contexts owned by the filter
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driver is returned.
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If neither the OwnerId nor the InstanceId is provided, any associated
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filter context will be returned.
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Return Value:
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A pointer to the filter context, or NULL if no match found.
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--*/
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{
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PFSRTL_PER_STREAM_CONTEXT ctx;
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PFSRTL_PER_STREAM_CONTEXT rtnCtx;
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PLIST_ENTRY list;
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ASSERT(AdvFcbHeader);
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ASSERT(FlagOn(AdvFcbHeader->Flags2,FSRTL_FLAG2_SUPPORTS_FILTER_CONTEXTS));
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ExAcquireFastMutex(AdvFcbHeader->FastMutex);
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rtnCtx = NULL;
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//
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// Use different loops depending on whether we are comparing both Ids or not.
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//
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if ( ARGUMENT_PRESENT(InstanceId) ) {
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MySearchList (&AdvFcbHeader->FilterContexts, list) {
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ctx = CONTAINING_RECORD(list, FSRTL_PER_STREAM_CONTEXT, Links);
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if (ctx->OwnerId == OwnerId && ctx->InstanceId == InstanceId) {
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rtnCtx = ctx;
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break;
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}
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}
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} else if ( ARGUMENT_PRESENT(OwnerId) ) {
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MySearchList (&AdvFcbHeader->FilterContexts, list) {
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ctx = CONTAINING_RECORD(list, FSRTL_PER_STREAM_CONTEXT, Links);
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if (ctx->OwnerId == OwnerId) {
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rtnCtx = ctx;
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break;
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}
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}
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} else if (!IsListEmpty(&AdvFcbHeader->FilterContexts)) {
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rtnCtx = (PFSRTL_PER_STREAM_CONTEXT)AdvFcbHeader->FilterContexts.Flink;
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}
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ExReleaseFastMutex(AdvFcbHeader->FastMutex);
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return rtnCtx;
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}
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NTKERNELAPI
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PFSRTL_PER_STREAM_CONTEXT
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FsRtlRemovePerStreamContext (
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IN PFSRTL_ADVANCED_FCB_HEADER AdvFcbHeader,
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IN PVOID OwnerId OPTIONAL,
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IN PVOID InstanceId OPTIONAL
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)
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/*++
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Routine Description:
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This routine deletes filter driver context associated with a stream.
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FsRtlRemoveFilterContext functions identically to FsRtlLookupFilterContext,
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except that the returned context has been removed from the list.
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Arguments:
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AdvFcbHeader - Advanced FCB Header for stream of interest.
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OwnerId - Used to identify context information belonging to a particular
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filter driver.
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InstanceId - Used to search for a particular instance of a filter driver
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context. If not provided, any of the contexts owned by the filter
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driver is removed and returned.
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If neither the OwnerId nor the InstanceId is provided, any associated
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filter context will be removed and returned.
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Return Value:
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A pointer to the filter context, or NULL if no match found.
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--*/
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{
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PFSRTL_PER_STREAM_CONTEXT ctx;
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PFSRTL_PER_STREAM_CONTEXT rtnCtx;
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PLIST_ENTRY list;
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if (!AdvFcbHeader ||
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!FlagOn(AdvFcbHeader->Flags2,FSRTL_FLAG2_SUPPORTS_FILTER_CONTEXTS))
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{
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return NULL;
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}
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ExAcquireFastMutex(AdvFcbHeader->FastMutex);
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rtnCtx = NULL;
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// Use different loops depending on whether we are comparing both Ids or not.
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if ( ARGUMENT_PRESENT(InstanceId) ) {
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MySearchList (&AdvFcbHeader->FilterContexts, list) {
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ctx = CONTAINING_RECORD(list, FSRTL_PER_STREAM_CONTEXT, Links);
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if (ctx->OwnerId == OwnerId && ctx->InstanceId == InstanceId) {
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rtnCtx = ctx;
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break;
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}
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}
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} else if ( ARGUMENT_PRESENT(OwnerId) ) {
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MySearchList (&AdvFcbHeader->FilterContexts, list) {
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ctx = CONTAINING_RECORD(list, FSRTL_PER_STREAM_CONTEXT, Links);
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if (ctx->OwnerId == OwnerId) {
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rtnCtx = ctx;
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break;
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}
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}
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} else if (!IsListEmpty(&AdvFcbHeader->FilterContexts)) {
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rtnCtx = (PFSRTL_PER_STREAM_CONTEXT)AdvFcbHeader->FilterContexts.Flink;
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}
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if (rtnCtx) {
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RemoveEntryList(&rtnCtx->Links); // remove the matched entry
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}
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ExReleaseFastMutex(AdvFcbHeader->FastMutex);
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return rtnCtx;
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}
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NTKERNELAPI
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VOID
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FsRtlTeardownPerStreamContexts (
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IN PFSRTL_ADVANCED_FCB_HEADER AdvFcbHeader
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)
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/*++
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Routine Description:
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This routine is called by filesystems to free the filter contexts
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associated with an FSRTL_COMMON_FCB_HEADER by calling the FreeCallback
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routine for each FilterContext.
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Arguments:
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FilterContexts - the address of the FilterContexts field within
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the FSRTL_COMMON_FCB_HEADER of the structure being torn down
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by the filesystem.
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Return Value:
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None.
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--*/
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{
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PFSRTL_PER_STREAM_CONTEXT ctx;
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PLIST_ENTRY ptr;
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BOOLEAN lockHeld;
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//
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// Acquire the lock because someone could be trying to free this
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// entry while we are trying to free it.
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//
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ExAcquireFastMutex( AdvFcbHeader->FastMutex );
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lockHeld = TRUE;
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try {
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while (!IsListEmpty( &AdvFcbHeader->FilterContexts )) {
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//
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// Unlink the top entry then release the lock. We must
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// release the lock before calling the use or their could
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// be potential locking order deadlocks.
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//
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ptr = RemoveHeadList( &AdvFcbHeader->FilterContexts );
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ExReleaseFastMutex(AdvFcbHeader->FastMutex);
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lockHeld = FALSE;
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//
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// Call filter to free this entry
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//
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ctx = CONTAINING_RECORD( ptr, FSRTL_PER_STREAM_CONTEXT, Links );
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ASSERT(ctx->FreeCallback);
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(*ctx->FreeCallback)( ctx );
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//
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// re-get the lock
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//
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ExAcquireFastMutex( AdvFcbHeader->FastMutex );
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lockHeld = TRUE;
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}
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} finally {
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if (lockHeld) {
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ExReleaseFastMutex( AdvFcbHeader->FastMutex );
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}
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}
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}
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//===========================================================================
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// Handles FileObject Contexts
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//===========================================================================
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//
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// Internal structure used to manage the Per FileObject Contexts.
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//
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typedef struct _PER_FILEOBJECT_CTXCTRL {
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//
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// This is a pointer to a Fast Mutex which may be used to
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// properly synchronize access to the FsRtl header. The
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// Fast Mutex must be nonpaged.
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//
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FAST_MUTEX FastMutex;
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//
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// This is a pointer to a list of context structures belonging to
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// filesystem filter drivers that are linked above the filesystem.
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// Each structure is headed by FSRTL_FILTER_CONTEXT.
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//
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LIST_ENTRY FilterContexts;
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} PER_FILEOBJECT_CTXCTRL, *PPER_FILEOBJECT_CTXCTRL;
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NTKERNELAPI
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NTSTATUS
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FsRtlInsertPerFileObjectContext (
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IN PFILE_OBJECT FileObject,
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IN PFSRTL_PER_FILEOBJECT_CONTEXT Ptr
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)
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/*++
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Routine Description:
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This routine associates a context with a file object.
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Arguments:
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FileObject - Specifies the file object of interest.
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Ptr - Pointer to the filter-specific context structure.
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The common header fields OwnerId and InstanceId should
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be filled in by the filter driver before calling.
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Return Value:
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STATUS_SUCCESS - operation succeeded.
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STATUS_INVALID_DEVICE_REQUEST - underlying filesystem does not support
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filter contexts.
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--*/
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{
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PPER_FILEOBJECT_CTXCTRL ctxCtrl;
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NTSTATUS status;
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//
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// Return if no file object
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//
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if (NULL == FileObject) {
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return STATUS_INVALID_PARAMETER;
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}
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if (!FsRtlSupportsPerFileObjectContexts(FileObject)) {
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return STATUS_INVALID_DEVICE_REQUEST;
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}
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//
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// Get the context control structure out of the file object extension
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//
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ctxCtrl = IoGetFileObjectFilterContext( FileObject );
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if (NULL == ctxCtrl) {
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//
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// There is not a control structure, allocate and initialize one
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//
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ctxCtrl = ExAllocatePoolWithTag( NonPagedPool,
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sizeof(PER_FILEOBJECT_CTXCTRL),
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'XCOF' );
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if (NULL == ctxCtrl) {
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return STATUS_INSUFFICIENT_RESOURCES;
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}
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ExInitializeFastMutex( &ctxCtrl->FastMutex );
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InitializeListHead( &ctxCtrl->FilterContexts );
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//
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// Insert into the file object extension
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//
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status = IoChangeFileObjectFilterContext( FileObject,
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ctxCtrl,
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TRUE );
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if (!NT_SUCCESS(status)) {
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//
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// If this operation fails it is because someone else inserted the
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// entry at the same time. In this case free the memory we
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// allocated and re-get the current value.
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//
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ExFreePool( ctxCtrl );
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ctxCtrl = IoGetFileObjectFilterContext( FileObject );
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if (NULL == ctxCtrl) {
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//
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// This should never actually happen. If it does it means
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// someone allocated and then freed a context very quickly.
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//
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ASSERT(!"This operation should not have failed");
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return STATUS_UNSUCCESSFUL;
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}
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}
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}
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ExAcquireFastMutex( &ctxCtrl->FastMutex );
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InsertHeadList( &ctxCtrl->FilterContexts, &Ptr->Links );
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ExReleaseFastMutex( &ctxCtrl->FastMutex );
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return STATUS_SUCCESS;
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}
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NTKERNELAPI
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PFSRTL_PER_FILEOBJECT_CONTEXT
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FsRtlLookupPerFileObjectContext (
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IN PFILE_OBJECT FileObject,
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IN PVOID OwnerId OPTIONAL,
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IN PVOID InstanceId OPTIONAL
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)
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/*++
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Routine Description:
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This routine lookups contexts associated with a file object.
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Arguments:
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FileObject - Specifies the file object of interest.
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OwnerId - Used to identify context information belonging to a particular
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filter driver.
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InstanceId - Used to search for a particular instance of a filter driver
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context. If not provided, any of the contexts owned by the filter
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driver is returned.
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If neither the OwnerId nor the InstanceId is provided, any associated
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filter context will be returned.
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Return Value:
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A pointer to the filter context, or NULL if no match found.
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--*/
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{
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PPER_FILEOBJECT_CTXCTRL ctxCtrl;
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PFSRTL_PER_FILEOBJECT_CONTEXT ctx;
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PFSRTL_PER_FILEOBJECT_CONTEXT rtnCtx;
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PLIST_ENTRY list;
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//
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// Return if no FileObjecty
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//
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if (NULL == FileObject) {
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return NULL;
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}
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//
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// Get the context control structure out of the file object extension
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//
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ctxCtrl = IoGetFileObjectFilterContext( FileObject );
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if (NULL == ctxCtrl) {
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return NULL;
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}
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rtnCtx = NULL;
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ExAcquireFastMutex( &ctxCtrl->FastMutex );
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//
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// Use different loops depending on whether we are comparing both Ids or not.
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//
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if ( ARGUMENT_PRESENT(InstanceId) ) {
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MySearchList (&ctxCtrl->FilterContexts, list) {
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ctx = CONTAINING_RECORD(list, FSRTL_PER_FILEOBJECT_CONTEXT, Links);
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if ((ctx->OwnerId == OwnerId) && (ctx->InstanceId == InstanceId)) {
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rtnCtx = ctx;
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break;
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}
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}
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} else if ( ARGUMENT_PRESENT(OwnerId) ) {
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MySearchList (&ctxCtrl->FilterContexts, list) {
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ctx = CONTAINING_RECORD(list, FSRTL_PER_FILEOBJECT_CONTEXT, Links);
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if (ctx->OwnerId == OwnerId) {
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rtnCtx = ctx;
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break;
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}
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}
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} else if (!IsListEmpty(&ctxCtrl->FilterContexts)) {
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rtnCtx = (PFSRTL_PER_FILEOBJECT_CONTEXT) ctxCtrl->FilterContexts.Flink;
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}
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|
|
ExReleaseFastMutex(&ctxCtrl->FastMutex);
|
|
|
|
return rtnCtx;
|
|
}
|
|
|
|
|
|
NTKERNELAPI
|
|
PFSRTL_PER_FILEOBJECT_CONTEXT
|
|
FsRtlRemovePerFileObjectContext (
|
|
IN PFILE_OBJECT FileObject,
|
|
IN PVOID OwnerId OPTIONAL,
|
|
IN PVOID InstanceId OPTIONAL
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine deletes contexts associated with a file object
|
|
|
|
Filter drivers must explicitly remove all context they associate with
|
|
a file object (otherwise the underlying filesystem will BugCheck at close).
|
|
This should be done at IRP_CLOSE time.
|
|
|
|
FsRtlRemoveFilterContext functions identically to FsRtlLookupFilterContext,
|
|
except that the returned context has been removed from the list.
|
|
|
|
Arguments:
|
|
|
|
FileObject - Specifies the file object of interest.
|
|
|
|
OwnerId - Used to identify context information belonging to a particular
|
|
filter driver.
|
|
|
|
InstanceId - Used to search for a particular instance of a filter driver
|
|
context. If not provided, any of the contexts owned by the filter
|
|
driver is removed and returned.
|
|
|
|
If neither the OwnerId nor the InstanceId is provided, any associated
|
|
filter context will be removed and returned.
|
|
|
|
Return Value:
|
|
|
|
A pointer to the filter context, or NULL if no match found.
|
|
|
|
--*/
|
|
|
|
{
|
|
PPER_FILEOBJECT_CTXCTRL ctxCtrl;
|
|
PFSRTL_PER_FILEOBJECT_CONTEXT ctx;
|
|
PFSRTL_PER_FILEOBJECT_CONTEXT rtnCtx;
|
|
PLIST_ENTRY list;
|
|
|
|
//
|
|
// Return if no file object
|
|
//
|
|
|
|
if (NULL == FileObject) {
|
|
|
|
return NULL;
|
|
}
|
|
|
|
//
|
|
// Get the context control structure out of the file object extension
|
|
//
|
|
|
|
ctxCtrl = IoGetFileObjectFilterContext( FileObject );
|
|
|
|
if (NULL == ctxCtrl) {
|
|
|
|
return NULL;
|
|
}
|
|
|
|
rtnCtx = NULL;
|
|
|
|
ExAcquireFastMutex( &ctxCtrl->FastMutex );
|
|
|
|
// Use different loops depending on whether we are comparing both Ids or not.
|
|
if ( ARGUMENT_PRESENT(InstanceId) ) {
|
|
|
|
MySearchList (&ctxCtrl->FilterContexts, list) {
|
|
|
|
ctx = CONTAINING_RECORD(list, FSRTL_PER_FILEOBJECT_CONTEXT, Links);
|
|
|
|
if ((ctx->OwnerId == OwnerId) && (ctx->InstanceId == InstanceId)) {
|
|
|
|
rtnCtx = ctx;
|
|
break;
|
|
}
|
|
}
|
|
|
|
} else if ( ARGUMENT_PRESENT(OwnerId) ) {
|
|
|
|
MySearchList (&ctxCtrl->FilterContexts, list) {
|
|
|
|
ctx = CONTAINING_RECORD(list, FSRTL_PER_FILEOBJECT_CONTEXT, Links);
|
|
|
|
if (ctx->OwnerId == OwnerId) {
|
|
|
|
rtnCtx = ctx;
|
|
break;
|
|
}
|
|
}
|
|
|
|
} else if (!IsListEmpty(&ctxCtrl->FilterContexts)) {
|
|
|
|
rtnCtx = (PFSRTL_PER_FILEOBJECT_CONTEXT)ctxCtrl->FilterContexts.Flink;
|
|
}
|
|
|
|
if (rtnCtx) {
|
|
|
|
RemoveEntryList(&rtnCtx->Links); // remove the matched entry
|
|
}
|
|
|
|
ExReleaseFastMutex( &ctxCtrl->FastMutex );
|
|
return rtnCtx;
|
|
}
|
|
|
|
|
|
VOID
|
|
FsRtlPTeardownPerFileObjectContexts (
|
|
IN PFILE_OBJECT FileObject
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine is called by filesystems to free the filter contexts
|
|
associated with an FSRTL_COMMON_FCB_HEADER by calling the FreeCallback
|
|
routine for each FilterContext.
|
|
|
|
Arguments:
|
|
|
|
FilterContexts - the address of the FilterContexts field within
|
|
the FSRTL_COMMON_FCB_HEADER of the structure being torn down
|
|
by the filesystem.
|
|
|
|
Return Value:
|
|
|
|
None.
|
|
|
|
--*/
|
|
|
|
{
|
|
PPER_FILEOBJECT_CTXCTRL ctxCtrl;
|
|
NTSTATUS status;
|
|
|
|
ASSERT(FileObject != NULL);
|
|
|
|
ctxCtrl = IoGetFileObjectFilterContext( FileObject );
|
|
|
|
if (NULL != ctxCtrl) {
|
|
|
|
status = IoChangeFileObjectFilterContext( FileObject,
|
|
ctxCtrl,
|
|
FALSE );
|
|
|
|
ASSERT(STATUS_SUCCESS == status);
|
|
ASSERT(IsListEmpty( &ctxCtrl->FilterContexts));
|
|
|
|
ExFreePool( ctxCtrl );
|
|
}
|
|
}
|
|
|
|
|
|
LOGICAL
|
|
FsRtlIsPagingFile (
|
|
IN PFILE_OBJECT FileObject
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine will return TRUE if the give file object is for a
|
|
paging file. It returns FALSE otherwise
|
|
|
|
Arguments:
|
|
|
|
FileObject - The file object to test
|
|
|
|
Return Value:
|
|
|
|
TRUE - if paging file
|
|
FALSE - if not
|
|
|
|
--*/
|
|
|
|
{
|
|
return MmIsFileObjectAPagingFile( FileObject );
|
|
}
|