113 lines
2.4 KiB
C
113 lines
2.4 KiB
C
/*%% (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: isindfreel.c /main/3 1995/10/23 11:41:03 rswiston $ */
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#ifndef lint
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static char sccsid[] = "@(#)isindfreel.c 1.3 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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* isfreelist.c
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*
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* Description:
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* Free list maintenance functions
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*/
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#include "isam_impl.h"
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extern Bufhdr *_isdisk_fix();
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/*
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* blkno = _isfreel_alloc()
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*
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* Allocate a new index page.
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*/
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Blkno
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_isindfreel_alloc(fcb)
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Fcb *fcb;
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{
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Bufhdr *pbhdr;
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char *p;
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int npointers;
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Blkno blkno;
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if (fcb->indfreelist == FREELIST_NOPAGE) {
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/*
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* We must write something to the buffer, or we will get
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* segmentation fault when using mapped I/O.
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*/
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fcb->indsize = _extend_file(fcb, fcb->indfd, fcb->indsize);
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return (fcb->indsize - 1);
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}
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pbhdr = _isdisk_fix(fcb, fcb->indfd, fcb->indfreelist, ISFIXWRITE);
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p = pbhdr->isb_buffer;
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npointers = ldshort(p + FL_NPOINTERS_OFF);
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if (npointers > 0) {
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blkno = ldblkno(p + FL_POINTERS_OFF + npointers * BLKNOSIZE);
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npointers--;
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stshort((short)npointers, p + FL_NPOINTERS_OFF);
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return (ldblkno(p + FL_POINTERS_OFF + npointers * BLKNOSIZE));
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}
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else {
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blkno = fcb->indfreelist;
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fcb->indfreelist = ldblkno(p + FL_NEXT_OFF);
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return (blkno);
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}
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}
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/*
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* _isfreel_free()
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*
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* Free an index page.
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*/
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void
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_isindfreel_free(fcb, blkno)
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Fcb *fcb;
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Blkno blkno;
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{
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Bufhdr *pbhdr;
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char *p;
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int npointers;
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if (fcb->indfreelist != FREELIST_NOPAGE) {
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pbhdr = _isdisk_fix(fcb, fcb->indfd, fcb->indfreelist, ISFIXWRITE);
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p = pbhdr->isb_buffer;
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npointers = ldshort(p + FL_NPOINTERS_OFF);
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if (npointers < FL_MAXNPOINTERS) {
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stblkno(blkno, p + FL_POINTERS_OFF + npointers * BLKNOSIZE);
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npointers++;
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stshort((short)npointers, p + FL_NPOINTERS_OFF);
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return;
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}
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}
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pbhdr = _isdisk_fix(fcb, fcb->indfd, blkno, ISFIXWRITE);
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p = pbhdr->isb_buffer;
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/* Mark page to indicate that it is in the free list. */
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stshort((short)PT_FREELIST, p + FL_TYPE_OFF);
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stshort((short)0, p + FL_NPOINTERS_OFF);
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stblkno(fcb->indfreelist, p + FL_NEXT_OFF);
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fcb->indfreelist = blkno;
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}
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