285 lines
7.2 KiB
C
285 lines
7.2 KiB
C
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/*****************************************************************************
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* *
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* BTDELETE.C *
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* *
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* Copyright (C) Microsoft Corporation 1989 - 1994. *
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* All Rights reserved. *
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* *
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******************************************************************************
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* *
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* Module Intent *
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* *
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* Btree deletion functions and helpers. *
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* *
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******************************************************************************
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* *
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* Current Owner: Binhn *
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* *
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*****************************************************************************/
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static char s_aszModule[]= __FILE__; /* For error report */
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#include <mvopsys.h>
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#include <misc.h>
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#include <orkin.h>
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#include <iterror.h>
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#include <wrapstor.h>
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#include <_mvutil.h>
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/* Put all functions into the same segment to avoid memory fragmentation
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* and load time surplus for the MAC
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*/
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// #pragma code_seg ("MVFS")
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/***************************************************************************
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*
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* Public Functions
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*
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***************************************************************************/
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/***************************************************************************\
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*
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* @doc PUBLIC API
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*
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* @func HRESULT PASCAL FAR | RcDeleteHbt |
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* delete a key from a btree.
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* Just copy over the key and update cbSlack.
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* Doesn't yet merge blocks less than half full or update key in
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* parent key if we deleted the first key in a block.
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*
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*
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* @parm HBT | hbt |
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* handle of the btree
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*
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* @parm KEY | key |
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* the key to delete from the btree
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*
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* @rdesc S_OK if delete works; ERR_NOTEXIST
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*
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* @rcomm Unfinished: doesn't do block merges or parent updates.
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*
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***************************************************************************/
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PUBLIC HRESULT PASCAL FAR EXPORT_API RcDeleteHbt(HBT hbt, KEY key)
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{
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QBTHR qbthr;
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HF hf;
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HRESULT rc;
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QCB qcb;
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QB qb;
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SHORT cb;
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BTPOS btpos;
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if ((qbthr = (QBTHR)_GLOBALLOCK(hbt)) == NULL)
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return(E_INVALIDARG);
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hf = qbthr->hf;
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if (qbthr->bth.bFlags & fFSOpenReadOnly)
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{
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rc = E_NOPERMISSION;
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exit0:
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_GLOBALUNLOCK(hbt);
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return rc;
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}
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/* look up the key */
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if ((rc = RcLookupByKey(hbt, key, &btpos, NULL)) != S_OK)
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goto exit0;
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qbthr->qCache = _GLOBALLOCK(qbthr->ghCache);
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// copy over this key and rec with subsequent keys and recs
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if ((qcb = QCacheBlock(qbthr, qbthr->bth.cLevels - 1)) == NULL)
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{
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rc = E_FAIL;
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exit1:
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_GLOBALUNLOCK(qbthr->ghCache);
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goto exit0;
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}
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qb = qcb->db.rgbBlock + btpos.iKey;
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cb = CbSizeKey((KEY)qb, qbthr, TRUE);
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cb += CbSizeRec(qb + cb, qbthr);
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QVCOPY(qb, qb + cb, (LONG)(qbthr->bth.cbBlock +
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(QB)&(qcb->db) - qb - cb - qcb->db.cbSlack));
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qcb->db.cbSlack += cb;
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// if this was the first key in the leaf block, update key in parent
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// >>>>> code goes here
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// if block is now less than half full, merge blocks
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// >>>>> code goes here
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qcb->db.cKeys--;
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qcb->bFlags |= fCacheDirty;
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qbthr->bth.lcEntries--;
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qbthr->bth.bFlags |= fFSDirty;
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rc = S_OK;
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goto exit1;
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}
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/***************************************************************************\
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*
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* @doc PUBLIC API
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*
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* @func HRESULT PASCAL FAR | RcTraverseHbt |
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* Traverses entire btree, calling a user function at each entry.
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* Optionally, the user can cause the current entry to be deleted.
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*
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* @parm HBT | hbt |
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* handle of the btree
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*
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* @parm TRAVERSE_FUNC | fnCallback |
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* Callback of the form DWORD Callback(KEY key, QB rec, DWORD dwUser)
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* return TRAVERSE_DONE for normal exit, TRAVERSE_DELETE to delete this
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* entry, TRAVERSE_INTERRUPT to interrupt and stop traversing.
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*
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* @parm DWORD | dwUser |
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* User data that gets passed into the callback.
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*
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* @rdesc S_OK if delete works
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* @comm Assumes that RcDeleteHbt does not do block merges. Keys and
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* records are limited to 256 bytes in this function
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*
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***************************************************************************/
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typedef DWORD (FAR PASCAL *TRAVERSE_FUNC) (KEY key, QB rec, DWORD dwUser);
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PUBLIC HRESULT PASCAL FAR EXPORT_API RcTraverseHbt(HBT hbt, TRAVERSE_FUNC fnCallback, DWORD dwUser)
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{
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QBTHR qbthr;
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HRESULT rc;
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BK bk;
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QCB qcb;
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QB qb;
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BTPOS btpos;
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BYTE * pKeyData;
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BYTE * pRecData;
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HRESULT errb;
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SHORT cbKey, cbRec;
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if ((hbt==NULL) || (!fnCallback))
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return E_INVALIDARG;
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if ((qbthr = (QBTHR)_GLOBALLOCK(hbt)) == NULL)
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return(E_INVALIDARG);
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if (qbthr->bth.lcEntries == (LONG)0)
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{
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rc = E_NOTEXIST;
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exit0:
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_GLOBALUNLOCK(hbt);
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return rc;
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}
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if ((bk = qbthr->bth.bkFirst) == bkNil)
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{
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rc = E_ASSERT;
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goto exit0;
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}
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if (qbthr->ghCache == NULL)
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{
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if ((rc = RcMakeCache(qbthr)) != S_OK)
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goto exit0;
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}
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qbthr->qCache = _GLOBALLOCK(qbthr->ghCache);
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if ((qcb = QFromBk(bk, (SHORT)(qbthr->bth.cLevels - 1), qbthr,
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&errb)) == NULL)
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{
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rc = errb;
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exit1:
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_GLOBALUNLOCK(qbthr->ghCache);
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goto exit0;
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}
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qb = qcb->db.rgbBlock + 2 * sizeof(BK);
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pKeyData=qb;
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cbKey = CbSizeKey((KEY)qb, qbthr, TRUE);
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qb += cbKey;
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pRecData=qb;
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cbRec = CbSizeRec(qb, qbthr);
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btpos.bk = bk;
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btpos.iKey = 2 * sizeof(BK);
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btpos.cKey = 0;
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while (1)
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{
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DWORD dwRes=(*fnCallback)((KEY)pKeyData,(QB)pRecData,dwUser);
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BTPOS btposNew;
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HRESULT errMore;
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errMore=RcNextPos( hbt, &btpos, &btposNew ); //==ERR_NOTEXIST)
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if (dwRes==1) // delete case
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{
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if (qbthr->bth.bFlags & fFSOpenReadOnly)
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{
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rc = E_NOPERMISSION;
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goto exit1;
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}
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// delete entry, and keep btposNew up to date during delete
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qcb = QFromBk(btpos.bk, (SHORT)(qbthr->bth.cLevels - 1), qbthr,&errb);
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//qb = qcb->db.rgbBlock + btpos.iKey;
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qb = qcb->db.rgbBlock + btpos.iKey;
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QVCOPY(qb, qb + cbKey + cbRec, (LONG)(qbthr->bth.cbBlock +
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(QB)&(qcb->db) - qb - (cbKey + cbRec) - qcb->db.cbSlack));
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qcb->db.cbSlack += cbKey + cbRec;
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qcb->db.cKeys--;
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qcb->bFlags |= fCacheDirty;
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qbthr->bth.lcEntries--;
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qbthr->bth.bFlags |= fFSDirty;
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if (btposNew.bk == btpos.bk)
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{
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btposNew.iKey-=cbKey + cbRec;
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btposNew.cKey--;
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}
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}
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else if (dwRes == 2)
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{
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rc = E_INTERRUPT;
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goto exit1;
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}
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if (errMore==S_OK)
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{
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btpos=btposNew;
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qcb = QFromBk(btpos.bk, (SHORT)(qbthr->bth.cLevels - 1), qbthr,&errb);
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qb = qcb->db.rgbBlock + btpos.iKey;
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pKeyData=qb;
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cbKey = CbSizeKey((KEY)qb, qbthr, TRUE);
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qb += cbKey;
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pRecData=qb;
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cbRec = CbSizeRec(qb, qbthr);
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}
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else
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break;
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}
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rc=S_OK;
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goto exit1;
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}
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/* EOF */
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