570 lines
14 KiB
C
570 lines
14 KiB
C
/*
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* CDE - Common Desktop Environment
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*
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* Copyright (c) 1993-2012, The Open Group. All rights reserved.
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*
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* These libraries and programs are free software; you can
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* redistribute them and/or modify them under the terms of the GNU
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* Lesser General Public License as published by the Free Software
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* Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* These libraries and programs are distributed in the hope that
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* they will be useful, but WITHOUT ANY WARRANTY; without even the
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* implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU Lesser General Public License for more
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* details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with these libraries and programs; if not, write
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* to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
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* Floor, Boston, MA 02110-1301 USA
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*/
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/*%% (c) Copyright 1993, 1994 Hewlett-Packard Company */
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/*%% (c) Copyright 1993, 1994 International Business Machines Corp. */
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/*%% (c) Copyright 1993, 1994 Sun Microsystems, Inc. */
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/*%% (c) Copyright 1993, 1994 Novell, Inc. */
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/*%% $XConsortium: isvarrec.c /main/3 1995/10/23 11:45:36 rswiston $ */
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#ifndef lint
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static char sccsid[] = "@(#)isvarrec.c 1.8 89/07/17 Copyr 1988 Sun Micro";
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#endif
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/*
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* Copyright (c) 1988 by Sun Microsystems, Inc.
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*/
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/*
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* isvarrec.c
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*
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* Description:
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* Fixed length record access (VLRA) module.
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*/
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#include "isam_impl.h"
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/* Local functions */
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long _vl_getpos(); /* Get offset in .rec file */
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int _vl_deleted(); /* 0/1 returns 1 if record is deleted */
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static void remove_from_chain2(); /* used by _vlrec_wrrec() */
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long _istail_insert();
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static void _istail_delete();
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static _istail_read();
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/*
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* _vlrec_write(fcb, record, recnum, reclen)
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*
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* Write a record.
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*
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* Input params:
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* FCB File Control Block
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* record record buffer
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* reclen record length (NOT USED)
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*
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* Output params:
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* recnum record number of the new record
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*
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* Returns 0 if record was written successfully, or -1 if any error.
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*/
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/*ARGSUSED*/
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int
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_vlrec_write(Fcb *fcb, char *record, Recno *recnum, int reclen)
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{
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Recno recnum2;
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long rec_position;
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long tailoff = VL_RECNOTAIL;
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char recnobuf [RECNOSIZE];
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char tailoffbuf[LONGSIZE];
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/*
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* Reuse a deleted record if one exits.
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* Otherwise, extend .rec file by a record.
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*/
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if (fcb->freerecno != NULL_RECNO) {
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recnum2 = fcb->freerecno;
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/*
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* Remove record from the chain of deleted records.
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*/
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rec_position = _vl_getpos(fcb, recnum2); /* Offset in .rec file */
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_cp_fromfile(fcb, fcb->datfd, recnobuf, rec_position + LONGSIZE, RECNOSIZE);
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fcb->freerecno = ldrecno(recnobuf);
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}
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else {
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recnum2 = ++(fcb->lastrecno);
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/*
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* Extend .rec file size if necessary.
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*/
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while (_vl_getpos(fcb, recnum2 + 1) > fcb->datsize * ISPAGESIZE) {
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fcb->datsize = _extend_file(fcb, fcb->datfd, fcb->datsize);
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}
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rec_position = _vl_getpos(fcb, recnum2); /* Offset in .rec file */
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}
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/*
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* Store variable part of record (the 'tail') in .var file.
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*/
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tailoff = _istail_insert(fcb, record + fcb->minreclen,
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reclen - fcb->minreclen);
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/*
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* Copy record to the .rec file. Mark record as undeleted.
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*/
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stlong(tailoff, tailoffbuf);
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_cp_tofile(fcb, fcb->datfd, tailoffbuf, rec_position, LONGSIZE);
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_cp_tofile(fcb, fcb->datfd, record, rec_position + LONGSIZE, fcb->minreclen);
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*recnum = recnum2;
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return (ISOK);
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}
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/*
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* _vlrec_read(fcb, record, recnum, reclen)
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*
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* Read a record.
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*
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* Input params:
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* FCB File Control Block
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* recnum record number of the record
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* reclen filled with the record size for compatibilty with
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* variable length records
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*
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* Output params:
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* record record buffer is filled with data
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*
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* Returns 0 if record was read successfully, or error code if any error.
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*/
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int
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_vlrec_read(Fcb *fcb, char *record, Recno recnum, int *reclen)
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{
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long rec_position;
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long tailoff;
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char tailoffbuf[LONGSIZE];
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/*
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* Check that recnum is within the range of existing record numbers.
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*/
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if (recnum < 1 || recnum > fcb->lastrecno)
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return (EENDFILE);
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rec_position = _vl_getpos(fcb, recnum); /* Offset in .rec file */
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/*
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* Check that the record is not marked as deleted.
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*/
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_cp_fromfile(fcb, fcb->datfd, tailoffbuf, rec_position, LONGSIZE);
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tailoff = ldlong(tailoffbuf);
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if (tailoff == VL_RECDELETED) {
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return (ENOREC);
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}
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/*
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* Copy record from the .at file.
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*/
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_cp_fromfile(fcb, fcb->datfd, record, rec_position + LONGSIZE, fcb->minreclen);
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*reclen = fcb->minreclen;
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/*
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* Get the 'tail' of the record if any.
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*/
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*reclen += _istail_read(fcb, tailoff, record + fcb->minreclen);
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if (*reclen > fcb->maxreclen)
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_isfatal_error("Corrupted file: too long variable length record");
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return (ISOK);
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}
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/*
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* pos = _vl_getpos(fcb, recnum)
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*
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* Calculate the position of record in .rec file.
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*/
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long
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_vl_getpos(Fcb *fcb, Recno recnum)
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{
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return ((long)(ISCNTLSIZE + (fcb->minreclen + LONGSIZE) * (recnum -1)));
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}
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/*
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* _vlrec_rewrite(fcb, record, recnum, reclen)
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*
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* Rewrite a record.
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*
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* Input params:
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* FCB File Control Block
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* recnum record number of the record
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* record new record
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* int reclen (NOT USED)
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*
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* Returns 0 if record was rewritten successfully, or error code if any error.
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*/
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/*ARGSUSED*/
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int
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_vlrec_rewrite(Fcb *fcb, char *record, Recno recnum, int reclen)
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{
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long rec_position;
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long tailoff;
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char tailoffbuf[LONGSIZE];
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/*
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* Check that recnum is within the range of existing record numbers.
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*/
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if (recnum < 1 || recnum > fcb->lastrecno)
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return (EENDFILE);
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rec_position = _vl_getpos(fcb, recnum); /* Offset in .rec file */
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/*
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* Check that the record is not marked as deleted.
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*/
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_cp_fromfile(fcb, fcb->datfd, tailoffbuf, rec_position, LONGSIZE);
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tailoff = ldlong(tailoffbuf);
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if (tailoff == VL_RECDELETED) {
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return (ENOREC);
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}
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/*
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* Store variable part of record (the 'tail') in .var file.
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*/
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tailoff = _istail_modify(fcb, tailoff, record + fcb->minreclen,
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reclen - fcb->minreclen);
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/*
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* Copy new record to the .rec file.
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*/
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stlong(tailoff, tailoffbuf);
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_cp_tofile(fcb, fcb->datfd, tailoffbuf, rec_position, LONGSIZE);
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_cp_tofile(fcb, fcb->datfd, record, rec_position + LONGSIZE, fcb->minreclen);
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return (ISOK);
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}
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/*
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* _vlrec_delete;(fcb, recnum)
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*
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* Rewrite a record.
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*
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* Input params:
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* FCB File Control Block
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* recnum record number of the record
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*
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* Returns 0 if record was rewritten successfully, or error code if any error.
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*/
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int
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_vlrec_delete(Fcb *fcb, Recno recnum)
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{
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long rec_position;
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long tailoff;
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char tailoffbuf[LONGSIZE];
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char recnobuf [RECNOSIZE];
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/*
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* Check that recnum is within the range of existing record numbers.
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*/
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if (recnum < 1 || recnum > fcb->lastrecno)
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return (EENDFILE);
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rec_position = _vl_getpos(fcb, recnum); /* Offset in .rec file */
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/*
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* Check that the record is not marked as deleted.
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*/
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_cp_fromfile(fcb, fcb->datfd, tailoffbuf, rec_position, LONGSIZE);
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tailoff = ldlong(tailoffbuf);
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if (tailoff == VL_RECDELETED) {
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return (ENOREC);
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}
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/*
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* Set the delete flag to VL_RECDELETED.
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*/
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tailoff = VL_RECDELETED;
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stlong(tailoff, tailoffbuf);
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_cp_tofile(fcb, fcb->datfd, tailoffbuf, rec_position, LONGSIZE);
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/*
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* Insert record into chain of deleted records.
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*/
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strecno(fcb->freerecno, recnobuf);
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_cp_tofile(fcb, fcb->datfd, recnobuf, rec_position + LONGSIZE, RECNOSIZE);
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fcb->freerecno = recnum;
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/*
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* Delete tail from .var file.
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*/
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return (ISOK);
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}
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/*
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* _vlrec_wrrec(fcb, record, recnum, reclen)
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*
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* Write a record by record number.
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*
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* Input params:
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* FCB File Control Block
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* recnum record number of the record
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* record record buffer
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* int reclen (NOT USED)
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*
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* Returns 0 if record was written successfully, or error code if any error.
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*
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* Note that _vlrec_wrrec() commits updates and syncs the FCB to avoid
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* buffer pool overflow.
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*/
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/*ARGSUSED*/
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int
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_vlrec_wrrec(Fcb *fcb, char *record, Recno recnum, int reclen)
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{
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long rec_position;
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long tailoff;
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char tailoffbuf[LONGSIZE];
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Recno recnum2;
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char recnumbuf [RECNOSIZE];
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/*
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* Check that recnum is not negative.
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*/
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if (recnum < 1)
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return (EBADARG);
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rec_position = _vl_getpos(fcb, recnum); /* Offset in .rec file */
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if (recnum > fcb->lastrecno) {
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/*
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* If the recnum is bigger than the highest record number in the .rec
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* file, extend the .rec file.
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*/
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while (_vl_getpos(fcb, recnum + 1) > fcb->datsize * ISPAGESIZE) {
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fcb->datsize = _extend_file(fcb, fcb->datfd, fcb->datsize);
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/* Sync the updates to avoid buffer pool overflow. */
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_isdisk_commit();
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_isdisk_sync();
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(void)_isfcb_cntlpg_w2(fcb);
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}
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/*
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* Mark all records in the range <fcb->lastrecno+1, recnum> as
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* deleted.
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*/
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tailoff = VL_RECDELETED;
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stlong(tailoff, tailoffbuf);
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for (recnum2 = fcb->lastrecno + 1; recnum2 <= recnum; recnum2++) {
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_cp_tofile(fcb, fcb->datfd, tailoffbuf, _vl_getpos(fcb, recnum2), LONGSIZE);
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strecno(fcb->freerecno, recnumbuf);
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_cp_tofile(fcb, fcb->datfd, recnumbuf,
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_vl_getpos(fcb, recnum2) + LONGSIZE, RECNOSIZE);
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fcb->freerecno = recnum2;
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/* Sync the updates to avoid buffer pool overflow. */
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_isdisk_commit();
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_isdisk_sync();
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fcb->lastrecno = recnum;
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(void)_isfcb_cntlpg_w2(fcb);
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}
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/*
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* Note that the disk structures are in a consistent state now,
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* the .rec was extended by a few records marked as 'deleted'.
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* This is important for subsequent rollbacks.
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*/
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}
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/*
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* If recnum specifies a record that has existed, check whether it
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* has been deleted. _vlrec_wrrec() does not override existing record.
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*/
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_cp_fromfile(fcb, fcb->datfd, tailoffbuf, rec_position, LONGSIZE);
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tailoff = ldlong(tailoffbuf);
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if (tailoff != VL_RECDELETED) {
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return (EDUPL);
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}
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/*
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* Remove the record from the chain of deleted records.
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*/
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remove_from_chain2(fcb, recnum);
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/*
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* Store variable part of record (the 'tail') in .var file.
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*/
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tailoff = _istail_insert(fcb, record + fcb->minreclen, reclen - fcb->minreclen);
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/*
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* Copy new record to the .rec file.
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*/
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stlong(tailoff, tailoffbuf);
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_cp_tofile(fcb, fcb->datfd, tailoffbuf, rec_position, LONGSIZE);
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_cp_tofile(fcb, fcb->datfd, record, rec_position + LONGSIZE, fcb->minreclen);
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return (ISOK);
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}
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/*
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* remove_from_chain(fcb, recnum)
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*
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* Remove record from the chain of deleted records.
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*/
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static void
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remove_from_chain2(Fcb *fcb, Recno recnum)
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{
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char recnobuf1 [RECNOSIZE] , recnobuf2 [RECNOSIZE];
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long pos1, pos2;
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Recno recnum2;
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pos1 = _vl_getpos(fcb, recnum);
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_cp_fromfile(fcb, fcb->datfd, recnobuf1, pos1 + LONGSIZE, RECNOSIZE);
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if (fcb->freerecno == recnum) {
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fcb->freerecno = ldrecno(recnobuf1);
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}
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else {
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recnum2 = fcb->freerecno;
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do {
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pos2 = _vl_getpos(fcb, recnum2);
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_cp_fromfile(fcb, fcb->datfd, recnobuf2, pos2 + LONGSIZE, RECNOSIZE);
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recnum2 = ldrecno(recnobuf2);
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} while (recnum2 != recnum && recnum2 != NULL_RECNO);
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_cp_tofile(fcb, fcb->datfd, recnobuf1, pos2 + LONGSIZE, RECNOSIZE);
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}
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}
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/*
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* The following are functions that manipulate the 'tails' of variable
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* records. The tail is the actual record with the fixed part removed
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* (fixed part starts at offset zero and its length is minimum record
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* length. The tails are stored in the .var file.
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*/
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/* Insert tail into .var file. Return offset in .var file */
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long _istail_insert(Fcb *fcb, char *tailp, int taillen)
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{
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char frameheadbuf [2 * SHORTSIZE];
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int framelen;
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long offset;
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/* printf ("_insert called, taillen %d\n", taillen); */
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if (taillen == 0)
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return (VL_RECNOTAIL);
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framelen = taillen + 2 * SHORTSIZE;
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/*
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* Set up frame header.
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*/
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stshort((short)taillen, frameheadbuf + VR_FRAMELEN_OFF);
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stshort((short)taillen, frameheadbuf + VR_TAILLEN_OFF);
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offset = fcb->varend;
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/*
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* Extend .var file if that is necesary.
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*/
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while (offset + framelen > fcb->varsize * ISPAGESIZE)
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fcb->varsize = _extend_file(fcb, fcb->varfd, fcb->varsize);
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/*
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* Copy frame head and tail to .var file.
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*/
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_cp_tofile(fcb, fcb->varfd, frameheadbuf, offset, 2 * SHORTSIZE);
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_cp_tofile(fcb, fcb->varfd, tailp, offset + 2 * SHORTSIZE, taillen);
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fcb->varend += taillen + 2 * SHORTSIZE;
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return (offset);
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}
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/* Remove tail from .var file */
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/* ARGSUSED */
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Static void _istail_delete(Fcb *fcb, long offset)
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{
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/*
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* Don't do anything in NetISAM 1.0. The tails are lost, the space
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* will be re-used after next restructuring: "copy -c file" command
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*/
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return;
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}
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/* Read tail from .var file */
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Static _istail_read(Fcb *fcb, long offset, char *buffer)
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{
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char frameheadbuf [2 * SHORTSIZE];
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int taillen;
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/* printf ("_read called, offset %d\n", offset); */
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if (offset == VL_RECNOTAIL)
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return (0);
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/*
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* Read frame header.
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*/
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_cp_fromfile(fcb, fcb->varfd, frameheadbuf, offset, 2 * SHORTSIZE);
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taillen = ldshort(frameheadbuf + VR_TAILLEN_OFF);
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_cp_fromfile(fcb, fcb->varfd, buffer, offset + 2 * SHORTSIZE, taillen);
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return (taillen);
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}
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/* Rewrite tail. Returns -1 if the new tail is longer than the original frame */
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int _istail_modify(Fcb *fcb, long offset, char *tailp, int taillen)
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{
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char frameheadbuf [2 * SHORTSIZE];
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int framelen;
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|
|
/*
|
|
* Trivial case: no old frame, no new tail.
|
|
*/
|
|
if (offset == VL_RECNOTAIL && taillen == 0)
|
|
return (offset);
|
|
|
|
if (offset != VL_RECNOTAIL) {
|
|
/*
|
|
* Read frame header.
|
|
*/
|
|
_cp_fromfile(fcb, fcb->varfd, frameheadbuf, offset, 2 * SHORTSIZE);
|
|
framelen = ldshort(frameheadbuf + VR_FRAMELEN_OFF);
|
|
}
|
|
else
|
|
framelen = 0;
|
|
|
|
if (taillen > framelen) {
|
|
/*
|
|
* Delete the old frame if the new tail does not fit.
|
|
* Insert the new tail at the end of .var file.
|
|
*/
|
|
|
|
_istail_delete(fcb, offset);
|
|
return (_istail_insert(fcb, tailp, taillen));
|
|
}
|
|
else {
|
|
/*
|
|
* The new tail fits in the existing frame.
|
|
*/
|
|
stshort((short)taillen, frameheadbuf + VR_TAILLEN_OFF);
|
|
_cp_tofile(fcb, fcb->varfd, frameheadbuf, offset, 2 * SHORTSIZE);
|
|
_cp_tofile(fcb, fcb->varfd, tailp, offset + 2 * SHORTSIZE, taillen);
|
|
|
|
return (offset);
|
|
}
|
|
}
|