397 lines
11 KiB
C
397 lines
11 KiB
C
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//+-------------------------------------------------------------------------
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//
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// Copyright (C) 1992, Microsoft Corporation.
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//
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// File: fcbsup.c
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//
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// Contents: Support routines for associating DFS_FCB records with
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// file objects, and looking them up again.
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//
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// Functions: DfsInitFcbs - Initialize the hash table for DFS_FCB lookup
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// DfsLookupFcb - Lookup an DFS_FCB associated with a file object
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// DfsAttachFcb - Associate an DFS_FCB with a file object
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// DfsDetachFcb - Remove the Association between an DFS_FCB and
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// a file object
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// DfsAllocateFcb - Allocate an FCB
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// DfsDestroyFcb - Deallocate an FCB
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//
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//--------------------------------------------------------------------------
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#include "dfsprocs.h"
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#include "attach.h"
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#include "fcbsup.h"
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#define Dbg 0x1000
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#define HASH(k,m) (((ULONG_PTR)(k)>>12^(ULONG_PTR)(k)>>2) & m)
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#define DEFAULT_HASH_SIZE 16 // default size of hash table
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NTSTATUS
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DfsInitFcbHashTable(
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IN ULONG cHash,
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OUT PFCB_HASH_TABLE *ppHashTable);
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(INIT, DfsInitFcbs)
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#pragma alloc_text(PAGE, DfsUninitFcbs)
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#pragma alloc_text(PAGE, DfsInitFcbHashTable)
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//
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// The following routines are not pageable because they acquire spinlocks.
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//
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// DfsLookupFcb
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// DfsAttachFcb
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// DfsDetachFcb
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//
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#endif
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//+-------------------------------------------------------------------------
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//
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// Function: DfsInitFcbs - Initialize the DFS_FCB lookup hash table
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//
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// Synopsis: This function initializes data structures which are
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// used for looking up an DFS_FCB associated with some open
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// file object.
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//
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// Arguments: [cHash] -- Size of the hash table to be allocated. Must be
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// a power of two. If zero, a default size is used.
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//
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// Returns: NTSTATUS -- STATUS_SUCCESS, unless memory allocation
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// fails.
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//
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// Note: The hash buckets are initialized to zero, then later
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// initialized to a list head when used. This is a debugging
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// aid to determine if some hash buckets are never used.
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//
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//--------------------------------------------------------------------------
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NTSTATUS
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DfsInitFcbHashTable(
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IN ULONG cHash,
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OUT PFCB_HASH_TABLE *ppHashTable)
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{
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PFCB_HASH_TABLE pHashTable;
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ULONG cbHashTable;
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if (cHash == 0) {
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cHash = DEFAULT_HASH_SIZE;
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}
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ASSERT ((cHash & (cHash-1)) == 0); // Assure cHash is a power of two
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cbHashTable = sizeof (FCB_HASH_TABLE) + (cHash-1)*sizeof (LIST_ENTRY);
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pHashTable = ExAllocatePoolWithTag(NonPagedPool, cbHashTable, ' sfD');
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if (pHashTable == NULL) {
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return STATUS_NO_MEMORY;
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}
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pHashTable->NodeTypeCode = DFS_NTC_FCB_HASH;
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pHashTable->NodeByteSize = (NODE_BYTE_SIZE) cbHashTable;
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pHashTable->HashMask = (cHash-1);
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KeInitializeSpinLock( &pHashTable->HashListSpinLock );
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RtlZeroMemory(&pHashTable->HashBuckets[0], cHash * sizeof (LIST_ENTRY));
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*ppHashTable = pHashTable;
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return(STATUS_SUCCESS);
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}
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NTSTATUS
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DfsInitFcbs(
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IN ULONG cHash
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) {
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NTSTATUS status;
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status = DfsInitFcbHashTable( cHash, &DfsData.FcbHashTable );
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return status;
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}
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VOID
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DfsUninitFcbs(
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VOID
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) {
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ExFreePool (DfsData.FcbHashTable);
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}
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//+-------------------------------------------------------------------------
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//
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// Function: DfsLookupFcb - Lookup an DFS_FCB in the hash table
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//
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// Synopsis: This function will lookup the DFS_FCB associated with
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// a particular file object.
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//
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// Arguments: [pFile] -- Pointer to file object for which the DFS_FCB is
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// being looked up.
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//
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// Returns: PVOID -- pointer to the DFS_FCB found, or NULL if none
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//
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// Algorithm: Knuth would call it hashing with conflict resoulution
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// by chaining.
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//
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// History: 20 Feb 1993 Alanw Created
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//
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//--------------------------------------------------------------------------
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PDFS_FCB
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DfsLookupFcb(
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IN PFILE_OBJECT pFile
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) {
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PLIST_ENTRY pListHead, pLink;
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PDFS_FCB pFCB;
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KIRQL SavedIrql;
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PFCB_HASH_TABLE pHashTable = DfsData.FcbHashTable;
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KeAcquireSpinLock( &pHashTable->HashListSpinLock, &SavedIrql );
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pListHead = &pHashTable->HashBuckets[ HASH(pFile, pHashTable->HashMask) ];
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if ((pListHead->Flink == NULL) || // list not initialized
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(pListHead->Flink == pListHead)) { // list empty
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KeReleaseSpinLock( &pHashTable->HashListSpinLock, SavedIrql );
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return NULL;
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}
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for (pLink = pListHead->Flink; pLink != pListHead; pLink = pLink->Flink) {
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pFCB = CONTAINING_RECORD(pLink, DFS_FCB, HashChain);
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if (pFCB->FileObject == pFile) {
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KeReleaseSpinLock( &pHashTable->HashListSpinLock, SavedIrql );
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return pFCB;
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}
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}
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KeReleaseSpinLock( &pHashTable->HashListSpinLock, SavedIrql );
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return NULL;
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}
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//+-------------------------------------------------------------------------
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//
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// Function: DfsAttachFcb - Inserts an DFS_FCB into the hash table
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//
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// Synopsis: This function associates an DFS_FCB to a file object. This
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// involves inserting it into the hash table.
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//
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// Arguments: [pFCB] -- Pointer to the DFS_FCB to be inserted.
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// [pFileObj] -- Pointer to the corresponding file object, used
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// as the hash key.
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//
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// Returns: -nothing-
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//
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//--------------------------------------------------------------------------
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VOID
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DfsAttachFcb(
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IN PFILE_OBJECT pFileObj,
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IN PDFS_FCB pFCB
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) {
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PFCB_HASH_TABLE pHashTable = (PFCB_HASH_TABLE) DfsData.FcbHashTable;
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PLIST_ENTRY pListHead;
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KIRQL SavedIrql;
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KeAcquireSpinLock( &pHashTable->HashListSpinLock, &SavedIrql );
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pListHead = &pHashTable->HashBuckets[ HASH(pFileObj, pHashTable->HashMask) ];
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if (pListHead->Flink == NULL) {
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InitializeListHead(pListHead);
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}
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InsertHeadList(pListHead, &pFCB->HashChain);
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KeReleaseSpinLock( &pHashTable->HashListSpinLock, SavedIrql );
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DebugTrace(0, Dbg, "Attached Fcb %08lx ", pFCB);
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DebugTrace(0, Dbg, "For Fileobject %08lx ", pFileObj);
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}
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//+-------------------------------------------------------------------------
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//
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// Function: DfsDetachFcb - Detach an DFS_FCB from the lookup hash table
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//
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// Synopsis: This function detaches an DFS_FCB from the hash table. This
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// involves just deleting it from the hash bucket chain.
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//
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// Arguments: [pFCB] -- Pointer to the DFS_FCB to be detached.
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// [pFileObj] -- Pointer to the corresponding file object, used
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// for debugging only.
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//
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// Returns: -nothing-
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//
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//--------------------------------------------------------------------------
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VOID
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DfsDetachFcb(
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IN PFILE_OBJECT pFileObj,
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IN PDFS_FCB pFCB
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) {
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PFCB_HASH_TABLE pHashTable = (PFCB_HASH_TABLE) DfsData.FcbHashTable;
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KIRQL SavedIrql;
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ASSERT(pFCB->FileObject == pFileObj);
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ASSERT(DfsLookupFcb(pFCB->FileObject) == pFCB);
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KeAcquireSpinLock( &pHashTable->HashListSpinLock, &SavedIrql );
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RemoveEntryList(&pFCB->HashChain);
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pFCB->FileObject = NULL;
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KeReleaseSpinLock( &pHashTable->HashListSpinLock, SavedIrql );
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DebugTrace(0, Dbg, "Detached Fcb %08lx ", pFCB);
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DebugTrace(0, Dbg, "For Fileobject %08lx ", pFileObj);
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}
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//+----------------------------------------------------------------------------
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//
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// Function: DfsAllocateFcb - Allocate an FCB
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//
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// Synopsis: This function allocates an FCB for a fileObject that is the
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// argument of a Create IRP. The most important thing this
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// Fcb contains is the full file name of the fileObject,
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// normalized for relative opens etc.
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//
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// Arguments: [DeviceObject] -- The Device on which the file is being
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// opened.
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// [FileObject] -- The file object for which the FCB is to be
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// allocated.
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// [Fcb] -- On successful return, has pointer to newly allocated
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// Fcb.
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//
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// Returns: [STATUS_SUCCESS] -- Successfully allocated FCB
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//
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// [STATUS_INSUFFICIENT_RESOURCES] -- Out of memory condition
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//
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//-----------------------------------------------------------------------------
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NTSTATUS
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DfsAllocateFcb(
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IN PDEVICE_OBJECT DeviceObject,
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IN PFILE_OBJECT FileObject,
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OUT PDFS_FCB *Fcb)
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{
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NTSTATUS status;
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PDFS_VOLUME_OBJECT deviceObject = (PDFS_VOLUME_OBJECT) DeviceObject;
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PDFS_FCB relatedFcb = NULL;
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PDFS_FCB fcb;
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PUNICODE_STRING relatedName;
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ULONG length;
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length = sizeof(DFS_FCB) +
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deviceObject->Provider.DeviceName.Length +
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sizeof(UNICODE_PATH_SEP) +
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FileObject->FileName.Length +
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sizeof(UNICODE_NULL);
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if (FileObject->RelatedFileObject != NULL) {
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relatedFcb = DfsLookupFcb( FileObject->RelatedFileObject );
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if (relatedFcb != NULL) {
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length += relatedFcb->FullFileName.Length +
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sizeof(UNICODE_PATH_SEP);
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relatedName = &relatedFcb->FullFileName;
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} else {
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length += FileObject->RelatedFileObject->FileName.Length;
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relatedName = &FileObject->RelatedFileObject->FileName;
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}
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} else {
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relatedName = NULL;
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}
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if (length <= MAXUSHORT) {
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fcb = (PDFS_FCB) ExAllocatePoolWithTag( NonPagedPool, length, ' sfD' );
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if (fcb != NULL) {
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RtlZeroMemory( fcb, length );
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fcb->NodeTypeCode = DFS_NTC_FCB;
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fcb->NodeByteSize = (USHORT)length;
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fcb->FullFileName.Length = 0;
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fcb->FullFileName.MaximumLength = (USHORT) (length - sizeof(DFS_FCB));
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fcb->FullFileName.Buffer = (PWCHAR) (fcb + 1);
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if (relatedName == NULL) {
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RtlCopyUnicodeString(
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&fcb->FullFileName,
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&deviceObject->Provider.DeviceName);
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} else {
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RtlCopyUnicodeString(
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&fcb->FullFileName,
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relatedName);
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}
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DfsConcatenateFilePath(
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&fcb->FullFileName,
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FileObject->FileName.Buffer,
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FileObject->FileName.Length);
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fcb->FileObject = FileObject;
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*Fcb = fcb;
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status = STATUS_SUCCESS;
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} else {
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status = STATUS_INSUFFICIENT_RESOURCES;
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}
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} else {
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status = STATUS_INSUFFICIENT_RESOURCES;
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}
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return( status );
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}
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//+----------------------------------------------------------------------------
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//
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// Function: DfsDestroyFcb
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//
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// Synopsis: Destroys an FCB allocated by DfsAllocateFcb
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//
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// Arguments: [Fcb] -- The Fcb to destroy.
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//
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// Returns: Nothing
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//
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//-----------------------------------------------------------------------------
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VOID
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DfsDestroyFcb(
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IN PDFS_FCB Fcb)
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{
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//
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// Make sure its gone from our Fcb tables
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//
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ASSERT( DfsLookupFcb( Fcb->FileObject ) != Fcb );
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//
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// Now, free it up.
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//
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ExFreePool( Fcb );
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}
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