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715 lines
17 KiB
C
715 lines
17 KiB
C
/*++
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Copyright (c) 1989-2000 Microsoft Corporation
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Module Name:
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PrefxSup.c
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Abstract:
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This module implements the Cdfs Prefix support routines
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--*/
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#include "cdprocs.h"
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//
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// The Bug check file id for this module
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//
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#define BugCheckFileId (CDFS_BUG_CHECK_PREFXSUP)
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//
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// Local support routines.
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//
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PNAME_LINK
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CdFindNameLink (
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_In_ PIRP_CONTEXT IrpContext,
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_In_ PRTL_SPLAY_LINKS *RootNode,
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_In_ PUNICODE_STRING Name
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);
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BOOLEAN
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CdInsertNameLink (
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_In_ PIRP_CONTEXT IrpContext,
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_Inout_ PRTL_SPLAY_LINKS *RootNode,
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_In_ PNAME_LINK NameLink
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);
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(PAGE, CdFindNameLink)
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#pragma alloc_text(PAGE, CdFindPrefix)
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#pragma alloc_text(PAGE, CdInsertNameLink)
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#pragma alloc_text(PAGE, CdInsertPrefix)
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#pragma alloc_text(PAGE, CdRemovePrefix)
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#endif
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VOID
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CdInsertPrefix (
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_In_ PIRP_CONTEXT IrpContext,
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_Inout_ PFCB Fcb,
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_In_ PCD_NAME Name,
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_In_ BOOLEAN IgnoreCase,
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_In_ BOOLEAN ShortNameMatch,
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_Inout_ PFCB ParentFcb
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)
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/*++
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Routine Description:
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This routine inserts the names in the given Lcb into the links for the
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parent.
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Arguments:
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Fcb - This is the Fcb whose name is being inserted into the tree.
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Name - This is the name for the component. The IgnoreCase flag tells
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us which entry this belongs to.
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IgnoreCase - Indicates if we should insert the case-insensitive name.
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ShortNameMatch - Indicates if this is the short name.
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ParentFcb - This is the ParentFcb. The prefix tree is attached to this.
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Return Value:
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None.
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--*/
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{
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ULONG PrefixFlags;
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PNAME_LINK NameLink;
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PPREFIX_ENTRY PrefixEntry;
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PRTL_SPLAY_LINKS *TreeRoot;
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PWCHAR NameBuffer;
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PAGED_CODE();
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//
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// Check if we need to allocate a prefix entry for the short name.
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// If we can't allocate one then fail quietly. We don't have to
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// insert the name.
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//
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PrefixEntry = &Fcb->FileNamePrefix;
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if (ShortNameMatch) {
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if (Fcb->ShortNamePrefix == NULL) {
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Fcb->ShortNamePrefix = ExAllocatePoolWithTag( CdPagedPool,
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sizeof( PREFIX_ENTRY ),
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TAG_PREFIX_ENTRY );
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if (Fcb->ShortNamePrefix == NULL) { return; }
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RtlZeroMemory( Fcb->ShortNamePrefix, sizeof( PREFIX_ENTRY ));
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}
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PrefixEntry = Fcb->ShortNamePrefix;
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}
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//
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// Capture the local variables for the separate cases.
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//
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if (IgnoreCase) {
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PrefixFlags = PREFIX_FLAG_IGNORE_CASE_IN_TREE;
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NameLink = &PrefixEntry->IgnoreCaseName;
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TreeRoot = &ParentFcb->IgnoreCaseRoot;
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} else {
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PrefixFlags = PREFIX_FLAG_EXACT_CASE_IN_TREE;
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NameLink = &PrefixEntry->ExactCaseName;
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TreeRoot = &ParentFcb->ExactCaseRoot;
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}
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//
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// If neither name is in the tree then check whether we have a buffer for this
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// name
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//
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if (!FlagOn( PrefixEntry->PrefixFlags,
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PREFIX_FLAG_EXACT_CASE_IN_TREE | PREFIX_FLAG_IGNORE_CASE_IN_TREE )) {
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//
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// Allocate a new buffer if the embedded buffer is too small.
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//
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NameBuffer = PrefixEntry->FileNameBuffer;
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if (Name->FileName.Length > BYTE_COUNT_EMBEDDED_NAME) {
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NameBuffer = ExAllocatePoolWithTag( CdPagedPool,
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Name->FileName.Length * 2,
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TAG_PREFIX_NAME );
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//
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// Exit if no name buffer.
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//
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if (NameBuffer == NULL) { return; }
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}
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//
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// Split the buffer and fill in the separate components.
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//
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PrefixEntry->ExactCaseName.FileName.Buffer = NameBuffer;
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PrefixEntry->IgnoreCaseName.FileName.Buffer = Add2Ptr( NameBuffer,
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Name->FileName.Length,
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PWCHAR );
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PrefixEntry->IgnoreCaseName.FileName.MaximumLength =
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PrefixEntry->IgnoreCaseName.FileName.Length =
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PrefixEntry->ExactCaseName.FileName.MaximumLength =
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PrefixEntry->ExactCaseName.FileName.Length = Name->FileName.Length;
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}
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//
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// Only insert the name if not already present.
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//
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if (!FlagOn( PrefixEntry->PrefixFlags, PrefixFlags )) {
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//
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// Initialize the name in the prefix entry.
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//
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RtlCopyMemory( NameLink->FileName.Buffer,
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Name->FileName.Buffer,
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Name->FileName.Length );
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CdInsertNameLink( IrpContext,
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TreeRoot,
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NameLink );
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PrefixEntry->Fcb = Fcb;
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SetFlag( PrefixEntry->PrefixFlags, PrefixFlags );
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}
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return;
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}
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VOID
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CdRemovePrefix (
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_In_ PIRP_CONTEXT IrpContext,
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_Inout_ PFCB Fcb
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)
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/*++
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Routine Description:
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This routine is called to remove all of the previx entries of a
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given Fcb from its parent Fcb.
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Arguments:
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Fcb - Fcb whose entries are to be removed.
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Return Value:
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None
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--*/
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{
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PAGED_CODE();
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UNREFERENCED_PARAMETER( IrpContext );
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//
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// Start with the short name prefix entry.
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//
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if (Fcb->ShortNamePrefix != NULL) {
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if (FlagOn( Fcb->ShortNamePrefix->PrefixFlags, PREFIX_FLAG_IGNORE_CASE_IN_TREE )) {
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Fcb->ParentFcb->IgnoreCaseRoot = RtlDelete( &Fcb->ShortNamePrefix->IgnoreCaseName.Links );
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}
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if (FlagOn( Fcb->ShortNamePrefix->PrefixFlags, PREFIX_FLAG_EXACT_CASE_IN_TREE )) {
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Fcb->ParentFcb->ExactCaseRoot = RtlDelete( &Fcb->ShortNamePrefix->ExactCaseName.Links );
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}
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ClearFlag( Fcb->ShortNamePrefix->PrefixFlags,
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PREFIX_FLAG_IGNORE_CASE_IN_TREE | PREFIX_FLAG_EXACT_CASE_IN_TREE );
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}
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//
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// Now do the long name prefix entries.
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//
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if (FlagOn( Fcb->FileNamePrefix.PrefixFlags, PREFIX_FLAG_IGNORE_CASE_IN_TREE )) {
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Fcb->ParentFcb->IgnoreCaseRoot = RtlDelete( &Fcb->FileNamePrefix.IgnoreCaseName.Links );
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}
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if (FlagOn( Fcb->FileNamePrefix.PrefixFlags, PREFIX_FLAG_EXACT_CASE_IN_TREE )) {
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Fcb->ParentFcb->ExactCaseRoot = RtlDelete( &Fcb->FileNamePrefix.ExactCaseName.Links );
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}
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ClearFlag( Fcb->FileNamePrefix.PrefixFlags,
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PREFIX_FLAG_IGNORE_CASE_IN_TREE | PREFIX_FLAG_EXACT_CASE_IN_TREE );
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//
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// Deallocate any buffer we may have allocated.
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//
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if ((Fcb->FileNamePrefix.ExactCaseName.FileName.Buffer != (PWCHAR) &Fcb->FileNamePrefix.FileNameBuffer) &&
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(Fcb->FileNamePrefix.ExactCaseName.FileName.Buffer != NULL)) {
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CdFreePool( &Fcb->FileNamePrefix.ExactCaseName.FileName.Buffer );
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Fcb->FileNamePrefix.ExactCaseName.FileName.Buffer = NULL;
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}
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return;
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}
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_Requires_lock_held_(_Global_critical_region_)
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VOID
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CdFindPrefix (
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_In_ PIRP_CONTEXT IrpContext,
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_Inout_ PFCB *CurrentFcb,
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_Inout_ PUNICODE_STRING RemainingName,
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_In_ BOOLEAN IgnoreCase
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)
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/*++
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Routine Description:
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This routine begins from the given CurrentFcb and walks through all of
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components of the name looking for the longest match in the prefix
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splay trees. The search is relative to the starting Fcb so the
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full name may not begin with a '\'. On return this routine will
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update Current Fcb with the lowest point it has travelled in the
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tree. It will also hold only that resource on return and it must
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hold that resource.
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Arguments:
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CurrentFcb - Address to store the lowest Fcb we find on this search.
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On return we will have acquired this Fcb. On entry this is the
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Fcb to examine.
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RemainingName - Supplies a buffer to store the exact case of the name being
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searched for. Initially will contain the upcase name based on the
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IgnoreCase flag.
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IgnoreCase - Indicates if we are doing a case-insensitive compare.
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Return Value:
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None
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--*/
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{
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UNICODE_STRING LocalRemainingName;
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UNICODE_STRING FinalName;
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PNAME_LINK NameLink;
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PPREFIX_ENTRY PrefixEntry;
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PAGED_CODE();
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//
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// Make a local copy of the input strings.
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//
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LocalRemainingName = *RemainingName;
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//
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// Loop until we find the longest matching prefix.
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//
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while (TRUE) {
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//
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// If there are no characters left or we are not at an IndexFcb then
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// return immediately.
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//
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if ((LocalRemainingName.Length == 0) ||
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(SafeNodeType( *CurrentFcb ) != CDFS_NTC_FCB_INDEX)) {
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return;
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}
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//
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// Split off the next component from the name.
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//
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CdDissectName( IrpContext,
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&LocalRemainingName,
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&FinalName );
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//
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// Check if this name is in the splay tree for this Scb.
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//
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if (IgnoreCase) {
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NameLink = CdFindNameLink( IrpContext,
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&(*CurrentFcb)->IgnoreCaseRoot,
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&FinalName );
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//
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// Get the prefix entry from this NameLink. Don't access any
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// fields within it until we verify we have a name link.
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//
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PrefixEntry = (PPREFIX_ENTRY) CONTAINING_RECORD( NameLink,
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PREFIX_ENTRY,
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IgnoreCaseName );
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} else {
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NameLink = CdFindNameLink( IrpContext,
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&(*CurrentFcb)->ExactCaseRoot,
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&FinalName );
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PrefixEntry = (PPREFIX_ENTRY) CONTAINING_RECORD( NameLink,
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PREFIX_ENTRY,
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ExactCaseName );
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}
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//
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// If we didn't find a match then exit.
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//
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if (NameLink == NULL) { return; }
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//
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// If this is a case-insensitive match then copy the exact case of the name into
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// the input buffer.
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//
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if (IgnoreCase) {
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RtlCopyMemory( FinalName.Buffer,
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PrefixEntry->ExactCaseName.FileName.Buffer,
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PrefixEntry->ExactCaseName.FileName.Length );
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}
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//
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// Update the caller's remaining name string to reflect the fact that we found
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// a match.
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//
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*RemainingName = LocalRemainingName;
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//
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// Move down to the next component in the tree. Acquire without waiting.
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// If this fails then lock the Fcb to reference this Fcb and then drop
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// the parent and acquire the child.
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//
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if (!CdAcquireFcbExclusive( IrpContext, PrefixEntry->Fcb, TRUE )) {
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//
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// If we can't wait then raise CANT_WAIT.
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//
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if (!FlagOn( IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT )) {
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CdRaiseStatus( IrpContext, STATUS_CANT_WAIT );
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}
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CdLockVcb( IrpContext, IrpContext->Vcb );
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PrefixEntry->Fcb->FcbReference += 1;
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CdUnlockVcb( IrpContext, IrpContext->Vcb );
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CdReleaseFcb( IrpContext, *CurrentFcb );
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CdAcquireFcbExclusive( IrpContext, PrefixEntry->Fcb, FALSE );
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CdLockVcb( IrpContext, IrpContext->Vcb );
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PrefixEntry->Fcb->FcbReference -= 1;
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CdUnlockVcb( IrpContext, IrpContext->Vcb );
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} else {
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CdReleaseFcb( IrpContext, *CurrentFcb );
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}
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*CurrentFcb = PrefixEntry->Fcb;
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}
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}
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//
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// Local support routine
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//
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PNAME_LINK
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CdFindNameLink (
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_In_ PIRP_CONTEXT IrpContext,
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_In_ PRTL_SPLAY_LINKS *RootNode,
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_In_ PUNICODE_STRING Name
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)
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/*++
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Routine Description:
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This routine searches through a splay link tree looking for a match for the
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input name. If we find the corresponding name we will rebalance the
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tree.
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Arguments:
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RootNode - Supplies the parent to search.
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Name - This is the name to search for. Note if we are doing a case
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insensitive search the name would have been upcased already.
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Return Value:
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PNAME_LINK - The name link found or NULL if there is no match.
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--*/
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{
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FSRTL_COMPARISON_RESULT Comparison;
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PNAME_LINK Node;
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PRTL_SPLAY_LINKS Links;
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PAGED_CODE();
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Links = *RootNode;
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while (Links != NULL) {
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Node = CONTAINING_RECORD( Links, NAME_LINK, Links );
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//
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// Compare the prefix in the tree with the full name
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//
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Comparison = CdFullCompareNames( IrpContext, &Node->FileName, Name );
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//
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// See if they don't match
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//
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if (Comparison == GreaterThan) {
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//
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// The prefix is greater than the full name
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// so we go down the left child
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//
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Links = RtlLeftChild( Links );
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//
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// And continue searching down this tree
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//
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} else if (Comparison == LessThan) {
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//
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// The prefix is less than the full name
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// so we go down the right child
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//
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Links = RtlRightChild( Links );
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//
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// And continue searching down this tree
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//
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} else {
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//
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// We found it.
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//
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// Splay the tree and save the new root.
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//
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*RootNode = RtlSplay( Links );
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return Node;
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}
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}
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//
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// We didn't find the Link.
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//
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return NULL;
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}
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//
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// Local support routine
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//
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BOOLEAN
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CdInsertNameLink (
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_In_ PIRP_CONTEXT IrpContext,
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_Inout_ PRTL_SPLAY_LINKS *RootNode,
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_In_ PNAME_LINK NameLink
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)
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/*++
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Routine Description:
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This routine will insert a name in the splay tree pointed to
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by RootNode.
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The name could already exist in this tree for a case-insensitive tree.
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In that case we simply return FALSE and do nothing.
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Arguments:
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RootNode - Supplies a pointer to the table.
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NameLink - Contains the new link to enter.
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Return Value:
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BOOLEAN - TRUE if the name is inserted, FALSE otherwise.
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--*/
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{
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FSRTL_COMPARISON_RESULT Comparison;
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PNAME_LINK Node;
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PAGED_CODE();
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RtlInitializeSplayLinks( &NameLink->Links );
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//
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// If we are the first entry in the tree, just become the root.
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//
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if (*RootNode == NULL) {
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*RootNode = &NameLink->Links;
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return TRUE;
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}
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Node = CONTAINING_RECORD( *RootNode, NAME_LINK, Links );
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while (TRUE) {
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//
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// Compare the prefix in the tree with the prefix we want
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// to insert.
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//
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Comparison = CdFullCompareNames( IrpContext, &Node->FileName, &NameLink->FileName );
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//
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// If we found the entry, return immediately.
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//
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if (Comparison == EqualTo) { return FALSE; }
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|
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//
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// If the tree prefix is greater than the new prefix then
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// we go down the left subtree
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//
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if (Comparison == GreaterThan) {
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//
|
||
// We want to go down the left subtree, first check to see
|
||
// if we have a left subtree
|
||
//
|
||
|
||
if (RtlLeftChild( &Node->Links ) == NULL) {
|
||
|
||
//
|
||
// there isn't a left child so we insert ourselves as the
|
||
// new left child
|
||
//
|
||
|
||
RtlInsertAsLeftChild( &Node->Links, &NameLink->Links );
|
||
|
||
//
|
||
// and exit the while loop
|
||
//
|
||
|
||
break;
|
||
|
||
} else {
|
||
|
||
//
|
||
// there is a left child so simply go down that path, and
|
||
// go back to the top of the loop
|
||
//
|
||
|
||
Node = CONTAINING_RECORD( RtlLeftChild( &Node->Links ),
|
||
NAME_LINK,
|
||
Links );
|
||
}
|
||
|
||
} else {
|
||
|
||
//
|
||
// The tree prefix is either less than or a proper prefix
|
||
// of the new string. We treat both cases as less than when
|
||
// we do insert. So we want to go down the right subtree,
|
||
// first check to see if we have a right subtree
|
||
//
|
||
|
||
if (RtlRightChild( &Node->Links ) == NULL) {
|
||
|
||
//
|
||
// These isn't a right child so we insert ourselves as the
|
||
// new right child
|
||
//
|
||
|
||
RtlInsertAsRightChild( &Node->Links, &NameLink->Links );
|
||
|
||
//
|
||
// and exit the while loop
|
||
//
|
||
|
||
break;
|
||
|
||
} else {
|
||
|
||
//
|
||
// there is a right child so simply go down that path, and
|
||
// go back to the top of the loop
|
||
//
|
||
|
||
Node = CONTAINING_RECORD( RtlRightChild( &Node->Links ),
|
||
NAME_LINK,
|
||
Links );
|
||
}
|
||
}
|
||
}
|
||
|
||
return TRUE;
|
||
}
|
||
|
||
|
||
|
||
|
||
|