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134 lines
3.4 KiB
134 lines
3.4 KiB
/* MDB Tools - A library for reading MS Access database file
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* Copyright (C) 2000 Brian Bruns
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include "mdbtools.h"
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#ifdef DMALLOC
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#include "dmalloc.h"
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#endif
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static guint32
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mdb_map_find_next0(MdbHandle *mdb, unsigned char *map, unsigned int map_sz, guint32 start_pg)
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{
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guint32 pgnum, i, usage_bitlen;
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unsigned char *usage_bitmap;
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pgnum = mdb_get_int32(map, 1);
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usage_bitmap = map + 5;
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usage_bitlen = (map_sz - 5) * 8;
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i = (start_pg >= pgnum) ? start_pg-pgnum+1 : 0;
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for (; i<usage_bitlen; i++) {
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if (usage_bitmap[i/8] & (1 << (i%8))) {
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return pgnum + i;
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}
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}
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/* didn't find anything */
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return 0;
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}
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static int
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mdb_map_find_next1(MdbHandle *mdb, unsigned char *map, unsigned int map_sz, guint32 start_pg)
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{
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guint32 map_ind, max_map_pgs, offset, usage_bitlen;
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/*
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* start_pg will tell us where to (re)start the scan
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* for the next data page. each usage_map entry points to a
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* 0x05 page which bitmaps (mdb->fmt->pg_size - 4) * 8 pages.
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*
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* map_ind gives us the starting usage_map entry
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* offset gives us a page offset into the bitmap
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*/
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usage_bitlen = (mdb->fmt->pg_size - 4) * 8;
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max_map_pgs = (map_sz - 1) / 4;
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map_ind = (start_pg + 1) / usage_bitlen;
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offset = (start_pg + 1) % usage_bitlen;
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for (; map_ind<max_map_pgs; map_ind++) {
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unsigned char *usage_bitmap;
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guint32 i, map_pg;
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if (!(map_pg = mdb_get_int32(map, (map_ind*4)+1))) {
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continue;
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}
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if(mdb_read_alt_pg(mdb, map_pg) != mdb->fmt->pg_size) {
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fprintf(stderr, "Oops! didn't get a full page at %d\n", map_pg);
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exit(1);
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}
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usage_bitmap = mdb->alt_pg_buf + 4;
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for (i=offset; i<usage_bitlen; i++) {
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if (usage_bitmap[i/8] & (1 << (i%8))) {
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return map_ind*usage_bitlen + i;
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}
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}
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offset = 0;
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}
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/* didn't find anything */
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return 0;
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}
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guint32
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mdb_map_find_next(MdbHandle *mdb, unsigned char *map, unsigned int map_sz, guint32 start_pg)
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{
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if (map[0] == 0) {
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return mdb_map_find_next0(mdb, map, map_sz, start_pg);
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} else if (map[0] == 1) {
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return mdb_map_find_next1(mdb, map, map_sz, start_pg);
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}
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fprintf(stderr, "Warning: unrecognized usage map type: %d\n", map[0]);
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return -1;
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}
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guint32
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mdb_alloc_page(MdbTableDef *table)
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{
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printf("Allocating new page\n");
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return 0;
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}
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guint32
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mdb_map_find_next_freepage(MdbTableDef *table, int row_size)
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{
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MdbCatalogEntry *entry = table->entry;
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MdbHandle *mdb = entry->mdb;
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guint32 pgnum;
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guint32 cur_pg = 0;
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int free_space;
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do {
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pgnum = mdb_map_find_next(mdb,
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table->free_usage_map,
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table->freemap_sz, cur_pg);
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if (!pgnum) {
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/* allocate new page */
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pgnum = mdb_alloc_page(table);
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return pgnum;
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}
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cur_pg = pgnum;
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mdb_read_pg(mdb, pgnum);
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free_space = mdb_pg_get_freespace(mdb);
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} while (free_space < row_size);
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return pgnum;
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}
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