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filtrctx.c File Reference

#include "FsRtlP.h"

Go to the source code of this file.

Defines

#define MySearchList(pHdr, Ptr)   for ( Ptr = (pHdr)->Flink; Ptr != (pHdr); Ptr = Ptr->Flink )
#define Dbg   (0x80000000)

Functions

NTKERNELAPI NTSTATUS FsRtlInsertFilterContext (IN PFILE_OBJECT FileObject, IN PFSRTL_FILTER_CONTEXT Ptr)
NTKERNELAPI PFSRTL_FILTER_CONTEXT FsRtlLookupFilterContextInternal (IN PFILE_OBJECT FileObject, IN PVOID OwnerId OPTIONAL, IN PVOID InstanceId OPTIONAL)
NTKERNELAPI PFSRTL_FILTER_CONTEXT FsRtlRemoveFilterContext (IN PFILE_OBJECT FileObject, IN PVOID OwnerId OPTIONAL, IN PVOID InstanceId OPTIONAL)
NTKERNELAPI VOID FsRtlTeardownFilterContexts (IN PLIST_ENTRY FilterContexts)

Define Documentation

#define Dbg   (0x80000000)
 

Definition at line 53 of file filtrctx.c.

#define MySearchList (  pHdr,
Ptr   )     for ( Ptr = (pHdr)->Flink; Ptr != (pHdr); Ptr = Ptr->Flink )
 

Definition at line 46 of file filtrctx.c.

Referenced by FsRtlLookupFilterContextInternal(), and FsRtlRemoveFilterContext().

Function Documentation

NTKERNELAPI NTSTATUS FsRtlInsertFilterContext (  IN PFILE_OBJECT  FileObject,
IN PFSRTL_FILTER_CONTEXT  Ptr
) 
 

Definition at line 58 of file filtrctx.c.

References ASSERT, FSRTL_FLAG2_SUPPORTS_FILTER_CONTEXTS, Header, PFSRTL_FILTER_CONTEXT, and Ptr. 

00064                    :
00065 
00066     This routine associates filter driver context with a stream.
00067 
00068 Arguments:
00069 
00070     FileObject - Specifies the stream of interest.
00071 
00072     Ptr - Pointer to the filter-specific context structure.
00073         The common header fields OwnerId and InstanceId should
00074         be filled in by the filter driver before calling.
00075 
00076 Return Value:
00077 
00078     STATUS_SUCCESS - operation succeeded.
00079 
00080     STATUS_INVALID_DEVICE_REQUEST - underlying filesystem does not support
00081         filter contexts.
00082 
00083 --*/
00084 
00085 {
00086     PFSRTL_COMMON_FCB_HEADER  Header;
00087 
00088     ASSERT(FileObject);
00089     ASSERT(FileObject->FsContext);
00090 
00091     Header = FileObject->FsContext;
00092 
00093     if (! (Header->Flags2 & FSRTL_FLAG2_SUPPORTS_FILTER_CONTEXTS) ) {
00094         return STATUS_INVALID_DEVICE_REQUEST;
00095     }
00096 
00097     ExAcquireFastMutex (Header->FastMutex);
00098 
00099     InsertHeadList (&Header->FilterContexts, &Ptr->Links);
00100 
00101     ExReleaseFastMutex(Header->FastMutex);
00102     return STATUS_SUCCESS;
00103 }

NTKERNELAPI PFSRTL_FILTER_CONTEXT FsRtlLookupFilterContextInternal (  IN PFILE_OBJECT  FileObject,
IN PVOID OwnerId  OPTIONAL,
IN PVOID InstanceId  OPTIONAL
) 
 

Definition at line 108 of file filtrctx.c.

References ASSERT, FSRTL_FILTER_CONTEXT, FSRTL_FLAG2_SUPPORTS_FILTER_CONTEXTS, Header, _FSRTL_FILTER_CONTEXT::InstanceId, List, MySearchList, NULL, and _FSRTL_FILTER_CONTEXT::OwnerId. 

00115                    :
00116 
00117     This routine lookups filter driver context associated with a stream.
00118 
00119     The macro FsRtlLookupFilterContext should be used instead of calling
00120     this routine directly.  The macro optimizes for the common case
00121     of an empty list.
00122 
00123 Arguments:
00124 
00125     FileObject - Specifies the stream of interest.
00126 
00127     OwnerId - Used to identify context information belonging to a particular
00128         filter driver.
00129 
00130     InstanceId - Used to search for a particular instance of a filter driver
00131         context.  If not provided, any of the contexts owned by the filter
00132         driver is returned.
00133 
00134     If neither the OwnerId nor the InstanceId is provided, any associated
00135         filter context will be returned.
00136 
00137 Return Value:
00138 
00139     A pointer to the filter context, or NULL if no match found.
00140 
00141 --*/
00142 
00143 {
00144     PFSRTL_COMMON_FCB_HEADER  Header;
00145     PFSRTL_FILTER_CONTEXT     Ctx, RtnCtx;
00146     PLIST_ENTRY               List;
00147 
00148     ASSERT(FileObject);
00149     ASSERT(FileObject->FsContext);
00150 
00151     Header = FileObject->FsContext;
00152 
00153     ASSERT (Header->Flags2 & FSRTL_FLAG2_SUPPORTS_FILTER_CONTEXTS);
00154 
00155     ExAcquireFastMutex (Header->FastMutex);
00156     RtnCtx = NULL;
00157 
00158   // Use different loops depending on whether we are comparing both Ids or not.
00159     if ( ARGUMENT_PRESENT(InstanceId) ) {
00160 
00161         MySearchList (&Header->FilterContexts, List) {
00162             Ctx  = CONTAINING_RECORD (List, FSRTL_FILTER_CONTEXT, Links);
00163             if (Ctx->OwnerId == OwnerId && Ctx->InstanceId == InstanceId) {
00164                 RtnCtx = Ctx;
00165                 break;
00166             }
00167         }
00168     } else if ( ARGUMENT_PRESENT(OwnerId) ) {
00169 
00170         MySearchList (&Header->FilterContexts, List) {
00171             Ctx  = CONTAINING_RECORD (List, FSRTL_FILTER_CONTEXT, Links);
00172             if (Ctx->OwnerId == OwnerId) {
00173                 RtnCtx = Ctx;
00174                 break;
00175             }
00176         }
00177     } else if (!IsListEmpty(&Header->FilterContexts)) {
00178 
00179         RtnCtx = (PFSRTL_FILTER_CONTEXT) Header->FilterContexts.Flink;
00180     }
00181 
00182     ExReleaseFastMutex(Header->FastMutex);
00183     return RtnCtx;
00184 }

NTKERNELAPI PFSRTL_FILTER_CONTEXT FsRtlRemoveFilterContext (  IN PFILE_OBJECT  FileObject,
IN PVOID OwnerId  OPTIONAL,
IN PVOID InstanceId  OPTIONAL
) 
 

Definition at line 189 of file filtrctx.c.

References ASSERT, FSRTL_FLAG2_SUPPORTS_FILTER_CONTEXTS, Header, _FSRTL_FILTER_CONTEXT::InstanceId, _FSRTL_FILTER_CONTEXT::Links, List, MySearchList, NULL, and _FSRTL_FILTER_CONTEXT::OwnerId. 

00196                    :
00197 
00198     This routine deletes filter driver context associated with a stream.
00199 
00200     Filter drivers must explicitly remove all context they associate with
00201     a stream (otherwise the underlying filesystem will BugCheck at close).
00202 
00203     FsRtlRemoveFilterContext functions identically to FsRtlLookupFilterContext,
00204     except that the returned context has been removed from the list.
00205 
00206 Arguments:
00207 
00208     FileObject - Specifies the stream of interest.
00209 
00210     OwnerId - Used to identify context information belonging to a particular
00211         filter driver.
00212 
00213     InstanceId - Used to search for a particular instance of a filter driver
00214         context.  If not provided, any of the contexts owned by the filter
00215         driver is removed and returned.
00216 
00217     If neither the OwnerId nor the InstanceId is provided, any associated
00218         filter context will be removed and returned.
00219 
00220 Return Value:
00221 
00222     A pointer to the filter context, or NULL if no match found.
00223 
00224 --*/
00225 
00226 {
00227     PFSRTL_COMMON_FCB_HEADER  Header;
00228     PFSRTL_FILTER_CONTEXT     Ctx, RtnCtx;
00229     PLIST_ENTRY               List;
00230 
00231     ASSERT(FileObject);
00232 
00233     Header = FileObject->FsContext;
00234 
00235     if ( !Header || !(Header->Flags2 & FSRTL_FLAG2_SUPPORTS_FILTER_CONTEXTS) ) {
00236         return NULL;
00237     }
00238 
00239     ExAcquireFastMutex (Header->FastMutex);
00240     RtnCtx = NULL;
00241 
00242   // Use different loops depending on whether we are comparing both Ids or not.
00243     if ( ARGUMENT_PRESENT(InstanceId) ) {
00244 
00245         MySearchList (&Header->FilterContexts, List) {
00246             Ctx  = CONTAINING_RECORD (List, FSRTL_FILTER_CONTEXT, Links);
00247             if (Ctx->OwnerId == OwnerId && Ctx->InstanceId == InstanceId) {
00248                 RtnCtx = Ctx;
00249                 break;
00250             }
00251         }
00252     } else if ( ARGUMENT_PRESENT(OwnerId) ) {
00253 
00254         MySearchList (&Header->FilterContexts, List) {
00255             Ctx  = CONTAINING_RECORD (List, FSRTL_FILTER_CONTEXT, Links);
00256             if (Ctx->OwnerId == OwnerId) {
00257                 RtnCtx = Ctx;
00258                 break;
00259             }
00260         }
00261     } else if (!IsListEmpty(&Header->FilterContexts)) {
00262 
00263         RtnCtx = (PFSRTL_FILTER_CONTEXT) Header->FilterContexts.Flink;
00264     }
00265 
00266     if (RtnCtx) {
00267         RemoveEntryList(&RtnCtx->Links);   // remove the matched entry
00268     }
00269     ExReleaseFastMutex(Header->FastMutex);
00270     return RtnCtx;
00271 }

NTKERNELAPI VOID FsRtlTeardownFilterContexts (  IN PLIST_ENTRY  FilterContexts  ) 
 

Definition at line 276 of file filtrctx.c.

References _FSRTL_FILTER_CONTEXT::FreeCallback. 

00281                    :
00282 
00283     This routine is called by filesystems to free the filter contexts
00284     associated with an FSRTL_COMMON_FCB_HEADER by calling the FreeCallback
00285     routine for each FilterContext.
00286 
00287     It is assumed that we do not need to acquire the FastMutex.
00288 
00289 Arguments:
00290 
00291     FilterContexts - the address of the FilterContexts field within
00292         the FSRTL_COMMON_FCB_HEADER of the structure being torn down
00293         by the filesystem.
00294 
00295 Return Value:
00296 
00297     None.
00298 
00299 --*/
00300 
00301 {
00302     PFSRTL_FILTER_CONTEXT ctx;
00303     PLIST_ENTRY           ptr;
00304 
00305     ptr = FilterContexts->Flink;
00306 
00307     while ( ptr != FilterContexts ) {
00308         ctx = CONTAINING_RECORD (ptr, FSRTL_FILTER_CONTEXT, Links);
00309         ptr = ptr->Flink;
00310         (*ctx->FreeCallback)(ctx);
00311     }
00312 
00313     InitializeListHead( FilterContexts );
00314     return;
00315 }

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