228 lines
8.2 KiB
C
228 lines
8.2 KiB
C
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//+-------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1992 - 1992.
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//
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// File: prefix.hxx
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//
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// Contents: PREFIX table definition
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//
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// History: SethuR -- Implemented
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//
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// Notes: The DFS prefix table data structure consists of three
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// entities and methods to manipulate them. They are the
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// DFS_PREFIX_TABLE_ENTRY,DFS_PREFIX_TABLE_BUCKET and the
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// DFS_PREFIX_TABLE.
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//
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// The DFS_PREFIX_TABLE is a hash table of DFS_PREFIX_TABLE_ENTRY's
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// wherein collisions are resolved through linear chaining. The
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// hash table is organized as an array of collision lists
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// (DFS_PREFIX_TABLE_BUCKET). A brief description with each of
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// these entities is attached to the declaration.
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//
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// There are certain characterstics that distinguish this
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// hash table from other hash tables. These are the extensions
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// provided to accomodate the special operations.
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//
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//--------------------------------------------------------------------------
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#ifndef __PREFIX_HXX__
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#define __PREFIX_HXX__
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//+---------------------------------------------------------------------
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//
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// Struct: DFS_PREFIX_TABLE_ENTRY
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//
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// History:
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//
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// Notes: Each DFS_PREFIX_TABLE entry is in reality a member of two linked
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// lists -- a doubly linked list chaining the entries in a bucket
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// and a singly linked list establishing the path from any entry to
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// the root of the name space. In addition we have the data associated
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// with each entry, viz., the name and the data (pData). We also
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// keep track of the number of children of each entry. It can also
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// be defined as the number of paths to the root of which this entry
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// is a member.
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//
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//----------------------------------------------------------------------
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typedef struct _DFS_PREFIX_TABLE_ENTRY_
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{
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struct _DFS_PREFIX_TABLE_ENTRY_ *pParentEntry;
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struct _DFS_PREFIX_TABLE_ENTRY_ *pNextEntry;
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struct _DFS_PREFIX_TABLE_ENTRY_ *pPrevEntry;
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//
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// pFirstChildEntry and pSiblingEntry are used purely for enumeration
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//
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struct _DFS_PREFIX_TABLE_ENTRY_ *pFirstChildEntry;
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struct _DFS_PREFIX_TABLE_ENTRY_ *pSiblingEntry;
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ULONG NoOfChildren;
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UNICODE_STRING PathSegment;
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PVOID pData;
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} DFS_PREFIX_TABLE_ENTRY, *PDFS_PREFIX_TABLE_ENTRY;
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//+---------------------------------------------------------------------
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//
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// Struct: DFS_PREFIX_TABLE_BUCKET
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//
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// History:
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//
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// Notes: The DFS_PREFIX_TABLE_BUCKET is a doubly linked list of
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// DFS_PREFIX_TABLE_ENTRY's. The current implementation employs
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// the notion of a sentinel entry associated with each bucket. The
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// end pointers are never null but are always looped back to the
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// sentinel entry. The reason we employ such an organization is that
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// it considerably simplifies the list manipulation routines. The
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// reason this needs to be a doubly linked list is that we would like
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// to have the ability of deleting entries without having to traverse
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// the buckets from beginning.
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//
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// The following inline methods ( macro defns. ) are provided for
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// inserting, deleting and looking up an entry in the bucket.
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//
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//----------------------------------------------------------------------
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typedef struct _PREFIX_TABLE_BUCKET_
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{
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ULONG NoOfEntries; // High water mark for entries hashing to the bkt.
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DFS_PREFIX_TABLE_ENTRY SentinelEntry;
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} PREFIX_TABLE_BUCKET, *PPREFIX_TABLE_BUCKET;
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//+---------------------------------------------------------------------
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//
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// Struct: NAME_PAGE
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//
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// History:
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//
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// Notes: The name segments associated with the various entries are all
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// stored together in a name page. This allows us to amortize the
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// memory allocation costs over a number of entries and also allows
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// us to speed up traversal ( for details see DFS_PREFIX_TABLE
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// definition ).
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//
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//----------------------------------------------------------------------
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#define FREESPACE_IN_NAME_PAGE ((PAGE_SIZE - sizeof(ULONG) - sizeof(PVOID)) / sizeof(WCHAR))
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typedef struct _NAME_PAGE_
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{
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struct _NAME_PAGE_ *pNextPage;
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LONG cFreeSpace; // free space avilable in WCHAR's
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WCHAR Names[FREESPACE_IN_NAME_PAGE];
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} NAME_PAGE, *PNAME_PAGE;
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typedef struct _NAME_PAGE_LIST_
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{
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PNAME_PAGE pFirstPage;
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} NAME_PAGE_LIST, *PNAME_PAGE_LIST;
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//+---------------------------------------------------------------------
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//
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// Struct: DFS_PREFIX_TABLE
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//
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// History:
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//
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// Notes: The DFS_PREFIX_TABLE is a hashed collection of DFS_PREFIX_TABLE_ENTRY
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// organized in the form of buckets. In addition one other space
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// conserving measure is adopted. There is only one copy of each
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// name segment stored in the table. As an example consider the
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// two pathnames \foo\bar and \bar\foo. We only store one copy of foo
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// and bar eventhough we accomdate both these paths. A beneficial
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// side effect of storing single copies is that our traversal of the
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// collision chain is considerably speeded up since once we have
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// located the pointer to the name, subsequent comparisons need merely
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// compare pointers as opposed to strings.
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//
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//----------------------------------------------------------------------
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#define NO_OF_HASH_BUCKETS 57
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typedef struct _DFS_PREFIX_TABLE
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{
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BOOLEAN CaseSensitive;
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NAME_PAGE_LIST NamePageList;
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//
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// NextEntry is used purely for enumeration
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//
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PDFS_PREFIX_TABLE_ENTRY NextEntry;
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DFS_PREFIX_TABLE_ENTRY RootEntry;
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PREFIX_TABLE_BUCKET Buckets[NO_OF_HASH_BUCKETS];
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#ifdef KERNEL_MODE
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// Zone for allocating DFS_PREFIX_TABLE entries .....
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ZONE_HEADER PrefixTableEntryZone;
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#else
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// A DFS_PREFIX_TABLE is part of DS_DATA. We need to make the sizes of
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// these structures identical in user and kernel mode, so that user-mode
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// utilities like dfsdump can work.
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CHAR UnusedBuffer[sizeof(ZONE_HEADER)];
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#endif
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} DFS_PREFIX_TABLE, *PDFS_PREFIX_TABLE;
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//+---------------------------------------------------------------------
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//
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// Struct: DFS_PREFIX_TABLE API.
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//
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// History:
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//
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// Notes: The following API's are provided for manipulating the
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// DFS_PREFIX_TABLE.
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//
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//----------------------------------------------------------------------
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extern
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NTSTATUS DfsInitializePrefixTable(PDFS_PREFIX_TABLE pTable,
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BOOLEAN fCaseSensitive);
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extern
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NTSTATUS DfsInsertInPrefixTable(PDFS_PREFIX_TABLE pTable,
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PUNICODE_STRING pPath,
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PVOID pData);
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extern
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NTSTATUS DfsLookupPrefixTable(PDFS_PREFIX_TABLE pTable,
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PUNICODE_STRING pPath,
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PUNICODE_STRING pSuffix,
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PVOID *ppData);
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extern
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NTSTATUS DfsRemoveFromPrefixTable(PDFS_PREFIX_TABLE pTable,
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PUNICODE_STRING pPath);
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NTSTATUS
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DfsFreePrefixTable(
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PDFS_PREFIX_TABLE pTable);
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//
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// The RTL Prefix Table function signatures are slightly different.
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// For now we will define a mapping between them to ease the porting
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// effort. Subsequently we will change our signatures to confirm to
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// the RTL routine.
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//
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#define DfsInitializeUnicodePrefix(pTable) \
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(DfsInitializePrefixTable(pTable,FALSE) == STATUS_SUCCESS)
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#define DfsRemoveUnicodePrefix(pTable,pPath) \
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(DfsRemoveFromPrefixTable(pTable,pPath) == STATUS_SUCCESS)
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#define DfsInsertUnicodePrefix(pTable,pPath,pData) \
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(DfsInsertInPrefixTable(pTable,pPath,pData) == STATUS_SUCCESS)
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PVOID DfsFindUnicodePrefix(PDFS_PREFIX_TABLE pTable,
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PUNICODE_STRING pPath,
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PUNICODE_STRING pSuffix);
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PVOID DfsNextUnicodePrefix(PDFS_PREFIX_TABLE pTable,
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BOOLEAN fRestart);
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#endif // __PREFIX_HXX__
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