Leaked source code of windows server 2003
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//+-------------------------------------------------------------------------
//
// Microsoft Windows
// Copyright (C) Microsoft Corporation, 1992 - 1992.
//
// File: prefix.hxx
//
// Contents: PREFIX table definition
//
// History: SethuR -- Implemented
//
// Notes: The DFS prefix table data structure consists of three
// entities and methods to manipulate them. They are the
// DFS_PREFIX_TABLE_ENTRY,DFS_PREFIX_TABLE_BUCKET and the
// DFS_PREFIX_TABLE.
//
// The DFS_PREFIX_TABLE is a hash table of DFS_PREFIX_TABLE_ENTRY's
// wherein collisions are resolved through linear chaining. The
// hash table is organized as an array of collision lists
// (DFS_PREFIX_TABLE_BUCKET). A brief description with each of
// these entities is attached to the declaration.
//
// There are certain characterstics that distinguish this
// hash table from other hash tables. These are the extensions
// provided to accomodate the special operations.
//
//--------------------------------------------------------------------------
#ifndef __PREFIX_H__
#define __PREFIX_H__
#include <dfsheader.h>
//+---------------------------------------------------------------------
//
// Struct: DFS_PREFIX_TABLE_ENTRY
//
// History:
//
// Notes: Each DFS_PREFIX_TABLE entry is in reality a member of two linked
// lists -- a doubly linked list chaining the entries in a bucket
// and a singly linked list establishing the path from any entry to
// the root of the name space. In addition we have the data associated
// with each entry, viz., the name and the data (pData). We also
// keep track of the number of children of each entry. It can also
// be defined as the number of paths to the root of which this entry
// is a member.
//
//----------------------------------------------------------------------
typedef struct _DFS_PREFIX_TABLE_ENTRY_
{
struct _DFS_PREFIX_TABLE_ENTRY_ *pParentEntry;
struct _DFS_PREFIX_TABLE_ENTRY_ *pNextEntry;
struct _DFS_PREFIX_TABLE_ENTRY_ *pPrevEntry;
//
// pFirstChildEntry and pSiblingEntry are used purely for enumeration
//
struct _DFS_PREFIX_TABLE_ENTRY_ *pFirstChildEntry;
struct _DFS_PREFIX_TABLE_ENTRY_ *pSiblingEntry;
ULONG Reference;
UNICODE_STRING PathSegment;
PVOID pData;
} DFS_PREFIX_TABLE_ENTRY, *PDFS_PREFIX_TABLE_ENTRY;
//+---------------------------------------------------------------------
//
// Struct: DFS_PREFIX_TABLE_BUCKET
//
// History:
//
// Notes: The DFS_PREFIX_TABLE_BUCKET is a doubly linked list of
// DFS_PREFIX_TABLE_ENTRY's. The current implementation employs
// the notion of a sentinel entry associated with each bucket. The
// end pointers are never null but are always looped back to the
// sentinel entry. The reason we employ such an organization is that
// it considerably simplifies the list manipulation routines. The
// reason this needs to be a doubly linked list is that we would like
// to have the ability of deleting entries without having to traverse
// the buckets from beginning.
//
// The following inline methods ( macro defns. ) are provided for
// inserting, deleting and looking up an entry in the bucket.
//
//----------------------------------------------------------------------
typedef struct _PREFIX_TABLE_BUCKET_
{
ULONG NoOfEntries; // High water mark for entries hashing to the bkt.
DFS_PREFIX_TABLE_ENTRY SentinelEntry;
} PREFIX_TABLE_BUCKET, *PPREFIX_TABLE_BUCKET;
//+---------------------------------------------------------------------
//
// Struct: DFS_PREFIX_TABLE
//
// History:
//
// Notes: The DFS_PREFIX_TABLE is a hashed collection of DFS_PREFIX_TABLE_ENTRY
// organized in the form of buckets. In addition one other space
// conserving measure is adopted. There is only one copy of each
// name segment stored in the table. As an example consider the
// two pathnames \foo\bar and \bar\foo. We only store one copy of foo
// and bar eventhough we accomdate both these paths. A beneficial
// side effect of storing single copies is that our traversal of the
// collision chain is considerably speeded up since once we have
// located the pointer to the name, subsequent comparisons need merely
// compare pointers as opposed to strings.
//
//----------------------------------------------------------------------
#define NO_OF_HASH_BUCKETS 57
typedef struct _DFS_PREFIX_TABLE
{
DFS_OBJECT_HEADER DfsHeader;
ULONG Flags;
ULONG TotalEntries;
LONG LockCount;
PVOID pPrefixTableLock;
//
// NextEntry is used purely for enumeration
//
PDFS_PREFIX_TABLE_ENTRY NextEntry;
DFS_PREFIX_TABLE_ENTRY RootEntry;
PREFIX_TABLE_BUCKET Buckets[NO_OF_HASH_BUCKETS];
} DFS_PREFIX_TABLE, *PDFS_PREFIX_TABLE;
#define PREFIX_TABLE_CASE_SENSITIVE 0x1
#define PREFIX_TABLE_TABLE_ALLOCATED 0x2
#define PREFIX_TABLE_LOCK_ALLOCATED 0x4
#define PREFIX_TABLE_LOCK_INITIALIZED 0x8
//--------------------------------------------------------------------------
//
// PREFIX TABLE UTILITIES
//
// A Path is a sequence of one or more name segments alternated with a
// distinguished concatenation character ( typically \ in FAT,NTFS,HPFS and
// / in UNIX file systems). These utilities are used to split a given path
// into the first path segment followed by the remainder of the path.
//
// SPLIT_PATH("foo\bar\bar1",Name,RemainingPath) binds Name to foo and
// RemainingPath to bar\bar1
//
// Similarly PROCESS_CASE_SENSITIVE_NAME and PROCESS_CASE_INSENSITIVE_NAME
// compute the hash signatures ( bucket no. ) for a given string.
//
//--------------------------------------------------------------------------
//
// MAX_PATH_SEGMENT_SIZE is simply used as a good size buffer to do prefix
// lookups and insertions. This should save us from having to allocate for
// most cases.
//
#define MAX_PATH_SEGMENT_SIZE 256
#define PATH_DELIMITER L'\\'
//+---------------------------------------------------------------------------
//
// Function: SPLIT_CASE_INSENSITIVE_PATH
//
// Synopsis: Split the path name around deleimiters.
//
// Arguments: [pPath] -- path to be split(PUNICODE_STRING)
//
// [pName] -- the leftmost component of the path(PUNICODE_STRING)
//
// [BucketNo] -- Hash Bucket no. corresponding to the name(ULONG)
//
// SideEffects: the UNICODE_STRING pointed to by pName and BucketNo are
// modified.
//
// PreRequisite: pName be associated with a valid buffer.
//
// History: 04-18-94 SethuR Created
//
// Notes: defined as a macro for inlining
//
//----------------------------------------------------------------------------
#define SPLIT_CASE_INSENSITIVE_PATH(pPath,pName,BucketNo) \
{ \
WCHAR *pPathBuffer = (pPath)->Buffer; \
WCHAR *pNameBuffer = (pName)->Buffer; \
WCHAR *pPathBufferEnd = &pPathBuffer[(pPath)->Length / sizeof(WCHAR)]; \
\
BucketNo = 0; \
while ((pPathBufferEnd != pPathBuffer) && \
((*pNameBuffer = *pPathBuffer++) != PATH_DELIMITER)) \
{ \
*pNameBuffer = (*pNameBuffer < L'a') \
? *pNameBuffer \
: ((*pNameBuffer < L'z') \
? (*pNameBuffer - L'a' + L'A') \
: RtlUpcaseUnicodeChar(*pNameBuffer)); \
BucketNo *= 131; \
BucketNo += *pNameBuffer; \
pNameBuffer++; \
} \
\
BucketNo = BucketNo % NO_OF_HASH_BUCKETS; \
*pNameBuffer = L'\0'; \
(pName)->Length = (USHORT)((CHAR *)pNameBuffer - (CHAR *)(pName)->Buffer); \
\
(pPath)->Length = (USHORT)((CHAR *)pPathBufferEnd - (CHAR *)pPathBuffer); \
(pPath)->Buffer = pPathBuffer; \
} \
//+---------------------------------------------------------------------------
//
// Function: SPLIT_CASE_SENSITIVE_PATH
//
// Synopsis: Split the patah name around deleimiters.
//
// Arguments: [pPath] -- path to be split(PUNICODE_STRING)
//
// [pName] -- the leftmost component of the path(PUNICODE_STRING)
//
// [BucketNo] -- Hash Bucket no. corresponding to the name(ULONG)
//
// SideEffects: the UNICODE_STRING pointed to by pName and BucketNo are modified.
//
// PreRequisite: pName be associated with a valid buffer.
//
// History: 04-18-94 SethuR Created
//
// Notes: defined as a macro for inlining
//
//----------------------------------------------------------------------------
#define SPLIT_CASE_SENSITIVE_PATH(pPath,pName,BucketNo) \
{ \
WCHAR *pPathBuffer = (pPath)->Buffer; \
WCHAR *pNameBuffer = (pName)->Buffer; \
WCHAR *pPathBufferEnd = &pPathBuffer[(pPath)->Length / sizeof(WCHAR)]; \
\
BucketNo = 0; \
while ((pPathBufferEnd != pPathBuffer) && \
((*pNameBuffer = *pPathBuffer++) != PATH_DELIMITER)) \
{ \
BucketNo *= 131; \
BucketNo += *pNameBuffer; \
pNameBuffer++; \
} \
\
BucketNo = BucketNo % NO_OF_HASH_BUCKETS; \
*pNameBuffer = L'\0'; \
(pName)->Length = (USHORT)((CHAR *)pNameBuffer - (CHAR *)(pName)->Buffer); \
\
(pPath)->Length = (USHORT)((CHAR *)pPathBufferEnd - (CHAR *)pPathBuffer); \
(pPath)->Buffer = pPathBuffer; \
} \
//+---------------------------------------------------------------------------
//
// Function: INITIALIZE_BUCKET
//
// Synopsis: Initializes a hash bucket.
//
// Arguments: [Bucket] -- the bucket to be initialized(DFS_PREFIX_TABLE_BUCKET)
//
// SideEffects: the bucket is intialized ( the collision list and count are
// initialized
//
// History: 04-18-94 SethuR Created
//
// Notes: defined as a macro for inlining
//
//----------------------------------------------------------------------------
#define INITIALIZE_BUCKET(Bucket) \
{ \
(Bucket).SentinelEntry.pNextEntry = &(Bucket).SentinelEntry; \
(Bucket).SentinelEntry.pPrevEntry = &(Bucket).SentinelEntry; \
(Bucket).NoOfEntries = 0; \
} \
//+---------------------------------------------------------------------------
//
// Function: LOOKUP_BUCKET
//
// Synopsis: lookups the bucket for an entry.
//
// Arguments: [Bucket] -- the bucket to be used (DFS_PREFIX_TABLE_BUCKET)
//
// [Name] -- the name to be looked up (UNICODE_STRING)
//
// [pParentEntry] -- the parent entry of the entry we are
// searching for.
//
// [pEntry] -- placeholder for the desired entry.
//
// [fNameFound] -- indicates if the name was found.
//
// SideEffects: Name,fNameFound and pEntry are modified
//
// History: 04-18-94 SethuR Created
//
// Notes: defined as a macro for inlining
//
// We only store one copy of a string irrespective of the no. of
// places it appears in, e.g. foo\bar and foo1\bar will result
// in only one copy of bar being stored. This implies that the
// lookup routine will have to return sufficient info. to prevent
// the allocation of memory space for a string. If on exit
// fNameFound is set to TRUE then this indicates that a similar
// string was located in the table and the Name.Buffer field is
// modified to point to the first instance of the string in
// the table.
//
//----------------------------------------------------------------------------
#define LOOKUP_BUCKET(Bucket,Name,pParentEntry,pEntry,fNameFound) \
{ \
PDFS_PREFIX_TABLE_ENTRY pCurEntry = Bucket.SentinelEntry.pNextEntry; \
\
fNameFound = FALSE; \
pEntry = NULL; \
\
while (pCurEntry != &Bucket.SentinelEntry) \
{ \
if (pCurEntry->PathSegment.Length == Name.Length) \
{ \
if (fNameFound && \
(pCurEntry->PathSegment.Buffer == Name.Buffer)) \
{ \
if (pCurEntry->pParentEntry == pParentEntry) \
{ \
pEntry = pCurEntry; \
break; \
} \
} \
else if (!memcmp(pCurEntry->PathSegment.Buffer, \
Name.Buffer, \
Name.Length)) \
{ \
fNameFound = TRUE; \
Name.Buffer = pCurEntry->PathSegment.Buffer; \
if (pCurEntry->pParentEntry == pParentEntry) \
{ \
pEntry = pCurEntry; \
break; \
} \
} \
} \
\
pCurEntry = pCurEntry->pNextEntry; \
} \
} \
//+---------------------------------------------------------------------------
//
// Function: INSERT_IN_BUCKET
//
// Synopsis: inserts the entry in the bucket
//
// Arguments: [Bucket] -- the bucket to be initialized(DFS_PREFIX_TABLE_BUCKET)
//
// [pEntry] -- the entry to be inserted
//
// SideEffects: Bucket is modified to include the entry
//
// History: 04-18-94 SethuR Created
//
// Notes: defined as a macro for inlining
//
//----------------------------------------------------------------------------
#define INSERT_IN_BUCKET(Bucket,pEntry) \
{ \
(Bucket).NoOfEntries++; \
(pEntry)->pPrevEntry = (Bucket).SentinelEntry.pPrevEntry; \
(pEntry)->pNextEntry = &((Bucket).SentinelEntry); \
((Bucket).SentinelEntry.pPrevEntry)->pNextEntry = (pEntry); \
(Bucket).SentinelEntry.pPrevEntry = (pEntry); \
} \
//+---------------------------------------------------------------------------
//
// Function: REMOVE_FROM_BUCKET
//
// Synopsis: removes the entry from the bucket
//
// Arguments: [pEntry] -- the entry to be inserted
//
// SideEffects: Bucket is modified to exclude the entry
//
// History: 04-18-94 SethuR Created
//
// Notes: defined as a macro for inlining
//
//----------------------------------------------------------------------------
#define REMOVE_FROM_BUCKET(pEntry) \
{ \
PDFS_PREFIX_TABLE_ENTRY pPrevEntry = (pEntry)->pPrevEntry; \
PDFS_PREFIX_TABLE_ENTRY pNextEntry = (pEntry)->pNextEntry; \
\
pPrevEntry->pNextEntry = pNextEntry; \
pNextEntry->pPrevEntry = pPrevEntry; \
} \
//+---------------------------------------------------------------------------
//
// Function: INSERT_IN_CHILD_LIST
//
// Synopsis: Inserts this entry in the parent's list of children
//
// Arguments: [pEntry] -- the entry to be inserted
//
// [pParentEntry] -- the entry into whose list of children
// pEntry has to be inserted.
//
// SideEffects: Parent's list of children is modified.
//
// History: 01-09-96 MilanS Created
//
// Notes: defined as a macro for inlining
//
//----------------------------------------------------------------------------
#define INSERT_IN_CHILD_LIST(pEntry, pParentEntry) \
{ \
PDFS_PREFIX_TABLE_ENTRY pLastChild; \
\
if (pParentEntry->pFirstChildEntry == NULL) { \
pParentEntry->pFirstChildEntry = pEntry; \
} else { \
for (pLastChild = pParentEntry->pFirstChildEntry; \
pLastChild->pSiblingEntry != NULL; \
pLastChild = pLastChild->pSiblingEntry) { \
NOTHING; \
} \
pLastChild->pSiblingEntry = pEntry; \
} \
}
//+----------------------------------------------------------------------------
//
// Function: REMOVE_FROM_CHILD_LIST
//
// Synopsis: Removes an entry from its parent's list of children
//
// Arguments: [pEntry] -- the Entry to remove from children list.
//
// SideEffects: The children list of pParentEntry is modified.
//
// History: 01-09-96 MilanS Created
//
// Notes: Defined as a macro for inlining.
//
// This routine will ASSERT if pEntry is not in the parent's
// list of children.
//
//-----------------------------------------------------------------------------
#define REMOVE_FROM_CHILD_LIST(pEntry) \
{ \
PDFS_PREFIX_TABLE_ENTRY pParentEntry = pEntry->pParentEntry; \
PDFS_PREFIX_TABLE_ENTRY pPrevSibling; \
\
if (pParentEntry->pFirstChildEntry == pEntry) { \
pParentEntry->pFirstChildEntry = pEntry->pSiblingEntry; \
} else { \
for (pPrevSibling = pParentEntry->pFirstChildEntry; \
pPrevSibling->pSiblingEntry != pEntry; \
pPrevSibling = pPrevSibling->pSiblingEntry) { \
ASSERT(pPrevSibling->pSiblingEntry != NULL); \
} \
pPrevSibling->pSiblingEntry = pEntry->pSiblingEntry; \
} \
}
//+---------------------------------------------------------------------------
//
// Function: INITIALIZE_PREFIX_TABLE_ENTRY
//
// Synopsis: initializes the prefix table entry
//
// Arguments: [pEntry] -- the entry to be initialized
//
// SideEffects: the prefix table entry is modified
//
// History: 04-18-94 SethuR Created
//
// Notes: defined as a macro for inlining
//
//----------------------------------------------------------------------------
#define INITIALIZE_PREFIX_TABLE_ENTRY(pEntry) \
{ \
RtlZeroMemory( pEntry, sizeof( DFS_PREFIX_TABLE_ENTRY ) ); \
(pEntry)->Reference = 1; \
} \
//+---------------------------------------------------------------------------
//
// Function: private fns. extern declarations
//
//----------------------------------------------------------------------------
extern
NTSTATUS _LookupPrefixTable(
IN PDFS_PREFIX_TABLE pTable,
IN UNICODE_STRING *pPath,
OUT UNICODE_STRING *pSuffix,
OUT PDFS_PREFIX_TABLE_ENTRY *ppEntry,
OUT PBOOLEAN pSubStringMatch );
VOID
DfsRemovePrefixTableEntry(
PDFS_PREFIX_TABLE pTable,
PDFS_PREFIX_TABLE_ENTRY pEntry );
//+---------------------------------------------------------------------------
//
// Function: ALLOCATION ROUTINES
//
// Synopsis: all the allocation routines are defined to be used in the KERNEL as
// well as user mode. The KERNEL mode is turned on by defining KERNEL
//
// History: 04-18-94 SethuR Created
//
// Notes: defined as a macro for inlining
//
//----------------------------------------------------------------------------
//
// We may be holding the PrefixLock shared. However, we won't need interlocks to
// just read the value.
//
#define IS_PREFIX_TABLE_LOCKED(_pTable) \
((_pTable)->LockCount > 0)
#define ALLOCATE_PREFIX_TABLE() \
PREFIX_TABLE_ALLOCATE_MEMORY(sizeof(DFS_PREFIX_TABLE))
#define FREE_PREFIX_TABLE(_ptable) \
PREFIX_TABLE_FREE_MEMORY(_ptable)
#ifdef KERNEL_MODE
#define ALLOCATE_NAME_BUFFER(cLength) \
ExAllocatePoolWithTag(PagedPool, cLength * sizeof(WCHAR), 'PsfD'); \
#define FREE_NAME_BUFFER(pName) ExFreePool(pName);
#define ALLOCATE_DFS_PREFIX_TABLE_ENTRY(pTable) \
(PDFS_PREFIX_TABLE_ENTRY) ExAllocatePoolWithTag(PagedPool,sizeof(DFS_PREFIX_TABLE_ENTRY), 'PsfD')
#define FREE_DFS_PREFIX_TABLE_ENTRY(pTable,pEntry) ExFreePool(pEntry);
#define COMPARE_MEMORY(s,d,l) (!RtlEqualMemory(s,d,l))
#define PREFIX_TABLE_ALLOCATE_MEMORY(size) ExAllocatePoolWithTag(PagedPool, size, 'PsfD')
#define PREFIX_TABLE_ALLOCATE_NONPAGED_MEMORY(size) ExAllocatePoolWithTag(NonPagedPool, size, 'PsfD')
#define PREFIX_TABLE_FREE_MEMORY(_p) ExFreePool(_p)
#define ALLOCATE_PREFIX_TABLE_LOCK() \
PREFIX_TABLE_ALLOCATE_NONPAGED_MEMORY(sizeof(ERESOURCE))
#define FREE_PREFIX_TABLE_LOCK(_plock) PREFIX_TABLE_FREE_MEMORY(_plock)
// We may be holding the PrefixLock shared. Use Interlocks to change the LockCount.
#define UNLOCK_PREFIX_TABLE(_ptable) {InterlockedDecrement( (ULONG volatile *)&(_ptable)->LockCount ); ExReleaseResourceLite((_ptable)->pPrefixTableLock);}
#define WRITE_LOCK_PREFIX_TABLE(_ptable,_sts) {(_sts) = STATUS_UNSUCCESSFUL;if((ExAcquireResourceExclusiveLite((_ptable)->pPrefixTableLock, TRUE) == TRUE)){InterlockedIncrement((ULONG volatile *)&(_ptable)->LockCount);(_sts) = STATUS_SUCCESS;}}
#define READ_LOCK_PREFIX_TABLE(_ptable,_sts) {(_sts) = STATUS_UNSUCCESSFUL;if((ExAcquireResourceSharedLite((_ptable)->pPrefixTableLock, TRUE) == TRUE)){InterlockedIncrement((ULONG volatile *)&(_ptable)->LockCount);(_sts) = STATUS_SUCCESS;}}
#define INITIALIZE_PREFIX_TABLE_LOCK(_plock) ExInitializeResourceLite(_plock)
#define UNINITIALIZE_PREFIX_TABLE_LOCK(_plock) ExDeleteResourceLite(_plock)
#else
#define ALLOCATE_PREFIX_TABLE_LOCK() \
PREFIX_TABLE_ALLOCATE_MEMORY(sizeof(CRITICAL_SECTION))
#define FREE_PREFIX_TABLE_LOCK(_plock) \
PREFIX_TABLE_FREE_MEMORY(_plock)
#define PREFIX_TABLE_SPIN_COUNT 4000
#define INITIALIZE_PREFIX_TABLE_LOCK(_plock) ((InitializeCriticalSectionAndSpinCount(_plock, PREFIX_TABLE_SPIN_COUNT) == FALSE) ? GetLastError() : STATUS_SUCCESS)
#define UNINITIALIZE_PREFIX_TABLE_LOCK(_plock) DeleteCriticalSection(_plock)
#define UNLOCK_PREFIX_TABLE(_pTable) {(_pTable)->LockCount--; LeaveCriticalSection((_pTable)->pPrefixTableLock); }
#define READ_LOCK_PREFIX_TABLE(_ptable, _sts) \
WRITE_LOCK_PREFIX_TABLE(_ptable, _sts)
#define WRITE_LOCK_PREFIX_TABLE(_pTable, _sts ) \
{ EnterCriticalSection((_pTable)->pPrefixTableLock); (_pTable)->LockCount++; (_sts) = STATUS_SUCCESS; }
#define ALLOCATE_NAME_BUFFER(cLength) \
PREFIX_TABLE_ALLOCATE_MEMORY(cLength * sizeof(WCHAR))
#define FREE_NAME_BUFFER(_pName) \
PREFIX_TABLE_FREE_MEMORY(_pName)
#define ALLOCATE_DFS_PREFIX_TABLE_ENTRY(_pTable) \
(PDFS_PREFIX_TABLE_ENTRY)PREFIX_TABLE_ALLOCATE_MEMORY(sizeof(DFS_PREFIX_TABLE_ENTRY))
#define FREE_DFS_PREFIX_TABLE_ENTRY(_pTable,_pEntry) \
PREFIX_TABLE_FREE_MEMORY(_pEntry)
#define COMPARE_MEMORY(s,d,l) memcmp(s,d,l)
#if defined (PREFIX_TABLE_HEAP_MEMORY)
#define PREFIX_TABLE_ALLOCATE_MEMORY(_sz) \
HeapAlloc(PrefixTableHeapHandle, 0, _sz)
#define PREFIX_TABLE_FREE_MEMORY(_addr) \
HeapFree(PrefixTableHeapHandle, 0, _addr)
#else
#define PREFIX_TABLE_ALLOCATE_MEMORY(_sz) malloc(_sz)
#define PREFIX_TABLE_FREE_MEMORY(_addr) free(_addr)
#endif
#endif /*!Kernel mode */
#endif // __PREFIX_H__