aboutsummaryrefslogtreecommitdiff
path: root/e2fsprogs/ext2fs/imager.c
blob: 596fbbebe002f4d1ee3206d27c722bde8aa77105 (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
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
/*
 * image.c --- writes out the critical parts of the filesystem as a
 * 	flat file.
 *
 * Copyright (C) 2000 Theodore Ts'o.
 *
 * Note: this uses the POSIX IO interfaces, unlike most of the other
 * functions in this library.  So sue me.  
 *
 * %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
#if HAVE_ERRNO_H
#include <errno.h>
#endif
#include <fcntl.h>
#include <time.h>
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

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

#ifndef HAVE_TYPE_SSIZE_T
typedef int ssize_t;
#endif

/*
 * This function returns 1 if the specified block is all zeros
 */
static int check_zero_block(char *buf, int blocksize)
{
	char	*cp = buf;
	int	left = blocksize;

	while (left > 0) {
		if (*cp++)
			return 0;
		left--;
	}
	return 1;
}

/*
 * Write the inode table out as a single block.
 */
#define BUF_BLOCKS	32

errcode_t ext2fs_image_inode_write(ext2_filsys fs, int fd, int flags)
{
	unsigned int	group, left, c, d;
	char		*buf, *cp;
	blk_t		blk;
	ssize_t		actual;
	errcode_t	retval;

	buf = malloc(fs->blocksize * BUF_BLOCKS);
	if (!buf)
		return ENOMEM;
	
	for (group = 0; group < fs->group_desc_count; group++) {
		blk = fs->group_desc[(unsigned)group].bg_inode_table;
		if (!blk)
			return EXT2_ET_MISSING_INODE_TABLE;
		left = fs->inode_blocks_per_group;
		while (left) {
			c = BUF_BLOCKS;
			if (c > left)
				c = left;
			retval = io_channel_read_blk(fs->io, blk, c, buf);
			if (retval)
				goto errout;
			cp = buf;
			while (c) {
				if (!(flags & IMAGER_FLAG_SPARSEWRITE)) {
					d = c;
					goto skip_sparse;
				}
				/* Skip zero blocks */
				if (check_zero_block(cp, fs->blocksize)) {
					c--;
					blk++;
					left--;
					cp += fs->blocksize;
					lseek(fd, fs->blocksize, SEEK_CUR);
					continue;
				}
				/* Find non-zero blocks */
				for (d=1; d < c; d++) {
					if (check_zero_block(cp + d*fs->blocksize, fs->blocksize))
						break;
				}
			skip_sparse:
				actual = write(fd, cp, fs->blocksize * d);
				if (actual == -1) {
					retval = errno;
					goto errout;
				}
				if (actual != (ssize_t) (fs->blocksize * d)) {
					retval = EXT2_ET_SHORT_WRITE;
					goto errout;
				}
				blk += d;
				left -= d;
				cp += fs->blocksize * d;
				c -= d;
			}
		}
	}
	retval = 0;

errout:
	free(buf);
	return retval;
}

/*
 * Read in the inode table and stuff it into place
 */
errcode_t ext2fs_image_inode_read(ext2_filsys fs, int fd, 
				  int flags EXT2FS_ATTR((unused)))
{
	unsigned int	group, c, left;
	char		*buf;
	blk_t		blk;
	ssize_t		actual;
	errcode_t	retval;

	buf = malloc(fs->blocksize * BUF_BLOCKS);
	if (!buf)
		return ENOMEM;
	
	for (group = 0; group < fs->group_desc_count; group++) {
		blk = fs->group_desc[(unsigned)group].bg_inode_table;
		if (!blk) {
			retval = EXT2_ET_MISSING_INODE_TABLE;
			goto errout;
		}
		left = fs->inode_blocks_per_group;
		while (left) {
			c = BUF_BLOCKS;
			if (c > left)
				c = left;
			actual = read(fd, buf, fs->blocksize * c);
			if (actual == -1) {
				retval = errno;
				goto errout;
			}
			if (actual != (ssize_t) (fs->blocksize * c)) {
				retval = EXT2_ET_SHORT_READ;
				goto errout;
			}
			retval = io_channel_write_blk(fs->io, blk, c, buf);
			if (retval)
				goto errout;
			
			blk += c;
			left -= c;
		}
	}
	retval = ext2fs_flush_icache(fs);

errout:
	free(buf);
	return retval;
}

/*
 * Write out superblock and group descriptors
 */
errcode_t ext2fs_image_super_write(ext2_filsys fs, int fd, 
				   int flags EXT2FS_ATTR((unused)))
{
	char		*buf, *cp;
	ssize_t		actual;
	errcode_t	retval;

	buf = malloc(fs->blocksize);
	if (!buf)
		return ENOMEM;

	/*
	 * Write out the superblock
	 */
	memset(buf, 0, fs->blocksize);
	memcpy(buf, fs->super, SUPERBLOCK_SIZE);
	actual = write(fd, buf, fs->blocksize);
	if (actual == -1) {
		retval = errno;
		goto errout;
	}
	if (actual != (ssize_t) fs->blocksize) {
		retval = EXT2_ET_SHORT_WRITE;
		goto errout;
	}

	/*
	 * Now write out the block group descriptors
	 */
	cp = (char *) fs->group_desc;
	actual = write(fd, cp, fs->blocksize * fs->desc_blocks);
	if (actual == -1) {
		retval = errno;
		goto errout;
	}
	if (actual != (ssize_t) (fs->blocksize * fs->desc_blocks)) {
		retval = EXT2_ET_SHORT_WRITE;
		goto errout;
	}
	
	retval = 0;

errout:
	free(buf);
	return retval;
}

/*
 * Read the superblock and group descriptors and overwrite them.
 */
errcode_t ext2fs_image_super_read(ext2_filsys fs, int fd, 
				  int flags EXT2FS_ATTR((unused)))
{
	char		*buf;
	ssize_t		actual, size;
	errcode_t	retval;

	size = fs->blocksize * (fs->group_desc_count + 1);
	buf = malloc(size);
	if (!buf)
		return ENOMEM;

	/*
	 * Read it all in.
	 */
	actual = read(fd, buf, size);
	if (actual == -1) {
		retval = errno;
		goto errout;
	}
	if (actual != size) {
		retval = EXT2_ET_SHORT_READ;
		goto errout;
	}

	/*
	 * Now copy in the superblock and group descriptors
	 */
	memcpy(fs->super, buf, SUPERBLOCK_SIZE);

	memcpy(fs->group_desc, buf + fs->blocksize,
	       fs->blocksize * fs->group_desc_count);

	retval = 0;

errout:
	free(buf);
	return retval;
}

/*
 * Write the block/inode bitmaps.
 */
errcode_t ext2fs_image_bitmap_write(ext2_filsys fs, int fd, int flags)
{
	char		*ptr;
	int		c, size;
	char		zero_buf[1024];
	ssize_t		actual;
	errcode_t	retval;

	if (flags & IMAGER_FLAG_INODEMAP) {
		if (!fs->inode_map) {
			retval = ext2fs_read_inode_bitmap(fs);
			if (retval)
				return retval;
		}
		ptr = fs->inode_map->bitmap;
		size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
	} else {
		if (!fs->block_map) {
			retval = ext2fs_read_block_bitmap(fs);
			if (retval)
				return retval;
		}
		ptr = fs->block_map->bitmap;
		size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
	}
	size = size * fs->group_desc_count;

	actual = write(fd, ptr, size);
	if (actual == -1) {
		retval = errno;
		goto errout;
	}
	if (actual != size) {
		retval = EXT2_ET_SHORT_WRITE;
		goto errout;
	}
	size = size % fs->blocksize;
	memset(zero_buf, 0, sizeof(zero_buf));
	if (size) {
		size = fs->blocksize - size;
		while (size) {
			c = size;
			if (c > (int) sizeof(zero_buf))
				c = sizeof(zero_buf);
			actual = write(fd, zero_buf, c);
			if (actual == -1) {
				retval = errno;
				goto errout;
			}
			if (actual != c) {
				retval = EXT2_ET_SHORT_WRITE;
				goto errout;
			}
			size -= c;
		}
	}
	retval = 0;
errout:
	return (retval);
}


/*
 * Read the block/inode bitmaps.
 */
errcode_t ext2fs_image_bitmap_read(ext2_filsys fs, int fd, int flags)
{
	char		*ptr, *buf = 0;
	int		size;
	ssize_t		actual;
	errcode_t	retval;

	if (flags & IMAGER_FLAG_INODEMAP) {
		if (!fs->inode_map) {
			retval = ext2fs_read_inode_bitmap(fs);
			if (retval)
				return retval;
		}
		ptr = fs->inode_map->bitmap;
		size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
	} else {
		if (!fs->block_map) {
			retval = ext2fs_read_block_bitmap(fs);
			if (retval)
				return retval;
		}
		ptr = fs->block_map->bitmap;
		size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
	}
	size = size * fs->group_desc_count;

	buf = malloc(size);
	if (!buf)
		return ENOMEM;

	actual = read(fd, buf, size);
	if (actual == -1) {
		retval = errno;
		goto errout;
	}
	if (actual != size) {
		retval = EXT2_ET_SHORT_WRITE;
		goto errout;
	}
	memcpy(ptr, buf, size);
	
	retval = 0;
errout:
	if (buf)
		free(buf);
	return (retval);
}