1 /* MDB Tools - A library for reading MS Access database file
2 * Copyright (C) 2000 Brian Bruns
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19 #include "mdbtools.h"
20
21 #ifdef DMALLOC
22 #include "dmalloc.h"
23 #endif
24
25 static gint32
mdb_map_find_next0(MdbHandle * mdb,unsigned char * map,unsigned int map_sz,guint32 start_pg)26 mdb_map_find_next0(MdbHandle *mdb, unsigned char *map, unsigned int map_sz, guint32 start_pg)
27 {
28 guint32 pgnum, i, usage_bitlen;
29 unsigned char *usage_bitmap;
30
31 pgnum = mdb_get_int32((char *)map, 1);
32 usage_bitmap = map + 5;
33 usage_bitlen = (map_sz - 5) * 8;
34
35 i = (start_pg >= pgnum) ? start_pg-pgnum+1 : 0;
36 for (; i<usage_bitlen; i++) {
37 if (usage_bitmap[i/8] & (1 << (i%8))) {
38 return pgnum + i;
39 }
40 }
41 /* didn't find anything */
42 return 0;
43 }
44 static gint32
mdb_map_find_next1(MdbHandle * mdb,unsigned char * map,unsigned int map_sz,guint32 start_pg)45 mdb_map_find_next1(MdbHandle *mdb, unsigned char *map, unsigned int map_sz, guint32 start_pg)
46 {
47 guint32 map_ind, max_map_pgs, offset, usage_bitlen;
48
49 /*
50 * start_pg will tell us where to (re)start the scan
51 * for the next data page. each usage_map entry points to a
52 * 0x05 page which bitmaps (mdb->fmt->pg_size - 4) * 8 pages.
53 *
54 * map_ind gives us the starting usage_map entry
55 * offset gives us a page offset into the bitmap
56 */
57 usage_bitlen = (mdb->fmt->pg_size - 4) * 8;
58 max_map_pgs = (map_sz - 1) / 4;
59 map_ind = (start_pg + 1) / usage_bitlen;
60 offset = (start_pg + 1) % usage_bitlen;
61
62 for (; map_ind<max_map_pgs; map_ind++) {
63 unsigned char *usage_bitmap;
64 guint32 i, map_pg;
65
66 if (!(map_pg = mdb_get_int32((char *)map, (map_ind*4)+1))) {
67 continue;
68 }
69 if(mdb_read_alt_pg(mdb, map_pg) != mdb->fmt->pg_size) {
70 fprintf(stderr, "Oops! didn't get a full page at %d\n", map_pg);
71 exit(1);
72 }
73
74 usage_bitmap = mdb->alt_pg_buf + 4;
75 for (i=offset; i<usage_bitlen; i++) {
76 if (usage_bitmap[i/8] & (1 << (i%8))) {
77 return map_ind*usage_bitlen + i;
78 }
79 }
80 offset = 0;
81 }
82 /* didn't find anything */
83 return 0;
84 }
85
86 /* returns 0 on EOF */
87 /* returns -1 on error (unsupported map type) */
88 gint32
mdb_map_find_next(MdbHandle * mdb,unsigned char * map,unsigned int map_sz,guint32 start_pg)89 mdb_map_find_next(MdbHandle *mdb, unsigned char *map, unsigned int map_sz, guint32 start_pg)
90 {
91 if (map[0] == 0) {
92 return mdb_map_find_next0(mdb, map, map_sz, start_pg);
93 } else if (map[0] == 1) {
94 return mdb_map_find_next1(mdb, map, map_sz, start_pg);
95 }
96
97 fprintf(stderr, "Warning: unrecognized usage map type: %d\n", map[0]);
98 return -1;
99 }
100 guint32
mdb_alloc_page(MdbTableDef * table)101 mdb_alloc_page(MdbTableDef *table)
102 {
103 printf("Allocating new page\n");
104 return 0;
105 }
106 guint32
mdb_map_find_next_freepage(MdbTableDef * table,int row_size)107 mdb_map_find_next_freepage(MdbTableDef *table, int row_size)
108 {
109 MdbCatalogEntry *entry = table->entry;
110 MdbHandle *mdb = entry->mdb;
111 guint32 pgnum;
112 guint32 cur_pg = 0;
113 int free_space;
114
115 do {
116 pgnum = mdb_map_find_next(mdb,
117 table->free_usage_map,
118 table->freemap_sz, cur_pg);
119 //printf("looking at page %d\n", pgnum);
120 if (!pgnum) {
121 /* allocate new page */
122 pgnum = mdb_alloc_page(table);
123 return pgnum;
124 } else if (pgnum==-1) {
125 fprintf(stderr, "Error: mdb_map_find_next_freepage error while reading maps.\n");
126 exit(1);
127 }
128 cur_pg = pgnum;
129
130 mdb_read_pg(mdb, pgnum);
131 free_space = mdb_pg_get_freespace(mdb);
132
133 } while (free_space < row_size);
134
135 //printf("page %d has %d bytes left\n", pgnum, free_space);
136
137 return pgnum;
138 }
139