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