summaryrefslogtreecommitdiff
path: root/e2fsprogs/ext2fs/rw_bitmaps.c
blob: b67a92599d207a24ce787ca395682a8ff20444fa (plain)
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
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
/*
 * rw_bitmaps.c --- routines to read and write the  inode and block bitmaps.
 *
 * Copyright (C) 1993, 1994, 1994, 1996 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <fcntl.h>
#include <time.h>
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#include "ext2_fs.h"
#include "ext2fs.h"
#include "e2image.h"

#if defined(__powerpc__) && defined(EXT2FS_ENABLE_SWAPFS)
/*
 * On the PowerPC, the big-endian variant of the ext2 filesystem
 * has its bitmaps stored as 32-bit words with bit 0 as the LSB
 * of each word.  Thus a bitmap with only bit 0 set would be, as
 * a string of bytes, 00 00 00 01 00 ...
 * To cope with this, we byte-reverse each word of a bitmap if
 * we have a big-endian filesystem, that is, if we are *not*
 * byte-swapping other word-sized numbers.
 */
#define EXT2_BIG_ENDIAN_BITMAPS
#endif

#ifdef EXT2_BIG_ENDIAN_BITMAPS
static void ext2fs_swap_bitmap(ext2_filsys fs, char *bitmap, int nbytes)
{
	__u32 *p = (__u32 *) bitmap;
	int n;
		
	for (n = nbytes / sizeof(__u32); n > 0; --n, ++p)
		*p = ext2fs_swab32(*p);
}
#endif

errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
{
	dgrp_t 		i;
	size_t		nbytes;
	errcode_t	retval;
	char * inode_bitmap = fs->inode_map->bitmap;
	char * bitmap_block = NULL;
	blk_t		blk;

	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	if (!(fs->flags & EXT2_FLAG_RW))
		return EXT2_ET_RO_FILSYS;
	if (!inode_bitmap)
		return 0;
	nbytes = (size_t) ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
	
	retval = ext2fs_get_mem(fs->blocksize, &bitmap_block);
	if (retval)
		return retval;
	memset(bitmap_block, 0xff, fs->blocksize);
	for (i = 0; i < fs->group_desc_count; i++) {
		memcpy(bitmap_block, inode_bitmap, nbytes);
		blk = fs->group_desc[i].bg_inode_bitmap;
		if (blk) {
#ifdef EXT2_BIG_ENDIAN_BITMAPS
			if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
			      (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
				ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
#endif
			retval = io_channel_write_blk(fs->io, blk, 1,
						      bitmap_block);
			if (retval)
				return EXT2_ET_INODE_BITMAP_WRITE;
		}
		inode_bitmap += nbytes;
	}
	fs->flags &= ~EXT2_FLAG_IB_DIRTY;
	ext2fs_free_mem(&bitmap_block);
	return 0;
}

errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
{
	dgrp_t 		i;
	unsigned int	j;
	int		nbytes;
	unsigned int	nbits;
	errcode_t	retval;
	char * block_bitmap = fs->block_map->bitmap;
	char * bitmap_block = NULL;
	blk_t		blk;

	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	if (!(fs->flags & EXT2_FLAG_RW))
		return EXT2_ET_RO_FILSYS;
	if (!block_bitmap)
		return 0;
	nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
	retval = ext2fs_get_mem(fs->blocksize, &bitmap_block);
	if (retval)
		return retval;
	memset(bitmap_block, 0xff, fs->blocksize);
	for (i = 0; i < fs->group_desc_count; i++) {
		memcpy(bitmap_block, block_bitmap, nbytes);
		if (i == fs->group_desc_count - 1) {
			/* Force bitmap padding for the last group */
			nbits = ((fs->super->s_blocks_count
				  - fs->super->s_first_data_block)
				 % EXT2_BLOCKS_PER_GROUP(fs->super));
			if (nbits)
				for (j = nbits; j < fs->blocksize * 8; j++)
					ext2fs_set_bit(j, bitmap_block);
		}
		blk = fs->group_desc[i].bg_block_bitmap;
		if (blk) {
#ifdef EXT2_BIG_ENDIAN_BITMAPS
			if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
			      (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
				ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
#endif
			retval = io_channel_write_blk(fs->io, blk, 1,
						      bitmap_block);
			if (retval)
				return EXT2_ET_BLOCK_BITMAP_WRITE;
		}
		block_bitmap += nbytes;
	}
	fs->flags &= ~EXT2_FLAG_BB_DIRTY;
	ext2fs_free_mem(&bitmap_block);
	return 0;
}

static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
{
	dgrp_t i;
	char *block_bitmap = 0, *inode_bitmap = 0;
	char *buf;
	errcode_t retval;
	int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
	int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
	blk_t	blk;

	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	fs->write_bitmaps = ext2fs_write_bitmaps;

	retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
	if (retval)
		return retval;
	if (do_block) {
		if (fs->block_map)
			ext2fs_free_block_bitmap(fs->block_map);
		sprintf(buf, "block bitmap for %s", fs->device_name);
		retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
		if (retval)
			goto cleanup;
		block_bitmap = fs->block_map->bitmap;
	}
	if (do_inode) {
		if (fs->inode_map)
			ext2fs_free_inode_bitmap(fs->inode_map);
		sprintf(buf, "inode bitmap for %s", fs->device_name);
		retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
		if (retval)
			goto cleanup;
		inode_bitmap = fs->inode_map->bitmap;
	}
	ext2fs_free_mem(&buf);

	if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
		if (inode_bitmap) {
			blk = (fs->image_header->offset_inodemap /
			       fs->blocksize);
			retval = io_channel_read_blk(fs->image_io, blk,
			     -(inode_nbytes * fs->group_desc_count),
			     inode_bitmap);
			if (retval)
				goto cleanup;
		}
		if (block_bitmap) {
			blk = (fs->image_header->offset_blockmap /
			       fs->blocksize);
			retval = io_channel_read_blk(fs->image_io, blk, 
			     -(block_nbytes * fs->group_desc_count),
			     block_bitmap);
			if (retval)
				goto cleanup;
		}
		return 0;
	}

	for (i = 0; i < fs->group_desc_count; i++) {
		if (block_bitmap) {
			blk = fs->group_desc[i].bg_block_bitmap;
			if (blk) {
				retval = io_channel_read_blk(fs->io, blk,
					     -block_nbytes, block_bitmap);
				if (retval) {
					retval = EXT2_ET_BLOCK_BITMAP_READ;
					goto cleanup;
				}
#ifdef EXT2_BIG_ENDIAN_BITMAPS
				if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
				      (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
					ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
#endif
			} else
				memset(block_bitmap, 0, block_nbytes);
			block_bitmap += block_nbytes;
		}
		if (inode_bitmap) {
			blk = fs->group_desc[i].bg_inode_bitmap;
			if (blk) {
				retval = io_channel_read_blk(fs->io, blk,
					     -inode_nbytes, inode_bitmap);
				if (retval) {
					retval = EXT2_ET_INODE_BITMAP_READ;
					goto cleanup;
				}
#ifdef EXT2_BIG_ENDIAN_BITMAPS
				if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
				      (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
					ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
#endif
			} else
				memset(inode_bitmap, 0, inode_nbytes);
			inode_bitmap += inode_nbytes;
		}
	}
	return 0;
	
cleanup:
	if (do_block) {
		ext2fs_free_mem(&fs->block_map);
		fs->block_map = 0;
	}
	if (do_inode) {
		ext2fs_free_mem(&fs->inode_map);
		fs->inode_map = 0;
	}
	if (buf)
		ext2fs_free_mem(&buf);
	return retval;
}

errcode_t ext2fs_read_inode_bitmap (ext2_filsys fs)
{
	return read_bitmaps(fs, 1, 0);
}

errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
{
	return read_bitmaps(fs, 0, 1);
}

errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
{

	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	if (fs->inode_map && fs->block_map)
		return 0;

	return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
}

errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
{
	errcode_t	retval;

	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	if (fs->block_map && ext2fs_test_bb_dirty(fs)) {
		retval = ext2fs_write_block_bitmap(fs);
		if (retval)
			return retval;
	}
	if (fs->inode_map && ext2fs_test_ib_dirty(fs)) {
		retval = ext2fs_write_inode_bitmap(fs);
		if (retval)
			return retval;
	}
	return 0;
}