aboutsummaryrefslogtreecommitdiff
path: root/e2fslib/openfs.c
blob: 042e25abec2a52b3142e3ce4a78d6f56f207f5bf (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
/*
 * openfs.c --- open an ext2 filesystem
 * 
 * Copyright (C) 1993, 1994, 1995, 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>
#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"
#include "e2image.h"

/*
 *  Note: if superblock is non-zero, block-size must also be non-zero.
 * 	Superblock and block_size can be zero to use the default size.
 *
 * Valid flags for ext2fs_open()
 * 
 * 	EXT2_FLAG_RW	- Open the filesystem for read/write.
 * 	EXT2_FLAG_FORCE - Open the filesystem even if some of the
 *				features aren't supported.
 *	EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
 */
errcode_t ext2fs_open(const char *name, int flags, int superblock,
		      int block_size, io_manager manager, ext2_filsys *ret_fs)
{
	ext2_filsys	fs;
	errcode_t	retval;
	int		i, j, groups_per_block;
	blk_t		group_block;
	char		*dest;
	struct ext2_group_desc *gdp;
	
	EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);

	retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys),
				(void **) &fs);
	if (retval)
		return retval;
	
	memset(fs, 0, sizeof(struct struct_ext2_filsys));
	fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
	fs->flags = flags;
	retval = manager->open(name, (flags & EXT2_FLAG_RW) ? IO_FLAG_RW : 0,
			       &fs->io);
	if (retval)
		goto cleanup;
	fs->io->app_data = fs;
	retval = ext2fs_get_mem(strlen(name)+1, (void **) &fs->device_name);
	if (retval)
		goto cleanup;
	strcpy(fs->device_name, name);
	retval = ext2fs_get_mem(SUPERBLOCK_SIZE, (void **) &fs->super);
	if (retval)
		goto cleanup;
	if (flags & EXT2_FLAG_IMAGE_FILE) {
		retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
					(void **) &fs->image_header);
		if (retval)
			goto cleanup;
		retval = io_channel_read_blk(fs->io, 0,
					     -sizeof(struct ext2_image_hdr),
					     fs->image_header);
		if (retval)
			goto cleanup;
		if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
			return EXT2_ET_MAGIC_E2IMAGE;
		superblock = 1;
		block_size = fs->image_header->fs_blocksize;
	}

	/*
	 * If the user specifies a specific block # for the
	 * superblock, then he/she must also specify the block size!
	 * Otherwise, read the master superblock located at offset
	 * SUPERBLOCK_OFFSET from the start of the partition.
	 *
	 * Note: we only save a backup copy of the superblock if we
	 * are reading the superblock from the primary superblock location.
	 */
	if (superblock) {
		if (!block_size) {
			retval = EXT2_ET_INVALID_ARGUMENT;
			goto cleanup;
		}
		io_channel_set_blksize(fs->io, block_size);
		group_block = superblock + 1;
		fs->orig_super = 0;
	} else {
		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
		superblock = 1;
		group_block = 0;
		retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
					(void **) &fs->orig_super);
		if (retval)
			goto cleanup;
	}
	retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
				     fs->super);
	if (retval)
		goto cleanup;
	if (fs->orig_super)
		memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);

#ifdef EXT2FS_ENABLE_SWAPFS
	if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) ||
	    (fs->flags & EXT2_FLAG_SWAP_BYTES)) {
		fs->flags |= EXT2_FLAG_SWAP_BYTES;

		ext2fs_swap_super(fs->super);
	}
#endif
	
	if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
		printf("%x, %x\n",fs->super->s_magic, EXT2_SUPER_MAGIC);
		retval = EXT2_ET_BAD_MAGIC;
		goto cleanup;
	}
	if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
		retval = EXT2_ET_REV_TOO_HIGH;
		goto cleanup;
	}

	/*
	 * Check for feature set incompatibility
	 */
	if (!(flags & EXT2_FLAG_FORCE)) {
		if (fs->super->s_feature_incompat &
		    ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
			retval = EXT2_ET_UNSUPP_FEATURE;
			goto cleanup;
		}
		if ((flags & EXT2_FLAG_RW) &&
		    (fs->super->s_feature_ro_compat &
		     ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
			retval = EXT2_ET_RO_UNSUPP_FEATURE;
			goto cleanup;
		}
		if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
		    (fs->super->s_feature_incompat &
		     EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
			retval = EXT2_ET_UNSUPP_FEATURE;
			goto cleanup;
		}
	}
	
	fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
	if (fs->blocksize == 0) {
		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
		goto cleanup;
	}
	fs->fragsize = EXT2_FRAG_SIZE(fs->super);
	fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
				       EXT2_INODE_SIZE(fs->super) +
				       EXT2_BLOCK_SIZE(fs->super) - 1) /
				      EXT2_BLOCK_SIZE(fs->super));
	if (block_size) {
		if (block_size != fs->blocksize) {
			retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
			goto cleanup;
		}
	}
	/*
	 * Set the blocksize to the filesystem's blocksize.
	 */
	io_channel_set_blksize(fs->io, fs->blocksize);

	/*
	 * If this is an external journal device, don't try to read
	 * the group descriptors, because they're not there.
	 */
	if (fs->super->s_feature_incompat &
	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
		fs->group_desc_count = 0;
		*ret_fs = fs;
		return 0;
	}
	
	/*
	 * Read group descriptors
	 */
	if ((EXT2_BLOCKS_PER_GROUP(fs->super)) == 0) {
		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
		goto cleanup;
	}
	fs->group_desc_count = (fs->super->s_blocks_count -
				fs->super->s_first_data_block +
				EXT2_BLOCKS_PER_GROUP(fs->super) - 1)
		/ EXT2_BLOCKS_PER_GROUP(fs->super);
	fs->desc_blocks = (fs->group_desc_count +
			   EXT2_DESC_PER_BLOCK(fs->super) - 1)
		/ EXT2_DESC_PER_BLOCK(fs->super);
	retval = ext2fs_get_mem(fs->desc_blocks * fs->blocksize,
				(void **) &fs->group_desc);
	if (retval)
		goto cleanup;
	if (!group_block)
		group_block = fs->super->s_first_data_block + 1;
	dest = (char *) fs->group_desc;
	for (i=0 ; i < fs->desc_blocks; i++) {
		retval = io_channel_read_blk(fs->io, group_block, 1, dest);
		if (retval)
			goto cleanup;
		group_block++;
#ifdef EXT2FS_ENABLE_SWAPFS
		if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
			gdp = (struct ext2_group_desc *) dest;
			groups_per_block = fs->blocksize /
				sizeof(struct ext2_group_desc);
			for (j=0; j < groups_per_block; j++)
				ext2fs_swap_group_desc(gdp++);
		}
#endif
		dest += fs->blocksize;
	}

	*ret_fs = fs;
	return 0;
cleanup:
	ext2fs_free(fs);
	return retval;
}