openfs.c revision 126a291c768b523bc228b276d3bea82675a86d09 
1/*
2 * openfs.c --- open an ext2 filesystem
3 *
4 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Public
8 * License.
9 * %End-Header%
10 */
11
12#include <stdio.h>
13#include <string.h>
14#if HAVE_UNISTD_H
15#include <unistd.h>
16#endif
17#include <fcntl.h>
18#include <time.h>
19#if HAVE_SYS_STAT_H
20#include <sys/stat.h>
21#endif
22#if HAVE_SYS_TYPES_H
23#include <sys/types.h>
24#endif
25
26#include "ext2_fs.h"
27
28
29#include "ext2fs.h"
30#include "e2image.h"
31
32blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
33{
34	int	bg;
35	int	has_super = 0;
36	int	ret_blk;
37
38	if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
39	    (i < fs->super->s_first_meta_bg))
40		return (group_block + i + 1);
41
42	bg = (fs->blocksize / sizeof (struct ext2_group_desc)) * i;
43	if (ext2fs_bg_has_super(fs, bg))
44		has_super = 1;
45	ret_blk = (fs->super->s_first_data_block + has_super +
46		   (bg * fs->super->s_blocks_per_group));
47	/*
48	 * If group_block is not the normal value, we're trying to use
49	 * the backup group descriptors and superblock --- so use the
50	 * alternate location of the second block group in the
51	 * metablock group.  Ideally we should be testing each bg
52	 * descriptor block individually for correctness, but we don't
53	 * have the infrastructure in place to do that.
54	 */
55	if (group_block != fs->super->s_first_data_block &&
56	    ((ret_blk + fs->super->s_blocks_per_group) <
57	     fs->super->s_blocks_count))
58		ret_blk += fs->super->s_blocks_per_group;
59	return ret_blk;
60}
61
62errcode_t ext2fs_open(const char *name, int flags, int superblock,
63		      unsigned int block_size, io_manager manager,
64		      ext2_filsys *ret_fs)
65{
66	return ext2fs_open2(name, 0, flags, superblock, block_size,
67			    manager, ret_fs);
68}
69
70/*
71 *  Note: if superblock is non-zero, block-size must also be non-zero.
72 * 	Superblock and block_size can be zero to use the default size.
73 *
74 * Valid flags for ext2fs_open()
75 *
76 * 	EXT2_FLAG_RW	- Open the filesystem for read/write.
77 * 	EXT2_FLAG_FORCE - Open the filesystem even if some of the
78 *				features aren't supported.
79 *	EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
80 */
81errcode_t ext2fs_open2(const char *name, const char *io_options,
82		       int flags, int superblock,
83		       unsigned int block_size, io_manager manager,
84		       ext2_filsys *ret_fs)
85{
86	ext2_filsys	fs;
87	errcode_t	retval;
88	unsigned long	i;
89	__u32		features;
90	int		j, groups_per_block, blocks_per_group, io_flags;
91	blk_t		group_block, blk;
92	char		*dest, *cp;
93	struct ext2_group_desc *gdp;
94
95	EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
96
97	retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
98	if (retval)
99		return retval;
100
101	memset(fs, 0, sizeof(struct struct_ext2_filsys));
102	fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
103	fs->flags = flags;
104	/* don't overwrite sb backups unless flag is explicitly cleared */
105	fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
106	fs->umask = 022;
107	retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
108	if (retval)
109		goto cleanup;
110	strcpy(fs->device_name, name);
111	cp = strchr(fs->device_name, '?');
112	if (!io_options && cp) {
113		*cp++ = 0;
114		io_options = cp;
115	}
116
117	io_flags = 0;
118	if (flags & EXT2_FLAG_RW)
119		io_flags |= IO_FLAG_RW;
120	if (flags & EXT2_FLAG_EXCLUSIVE)
121		io_flags |= IO_FLAG_EXCLUSIVE;
122	retval = manager->open(fs->device_name, io_flags, &fs->io);
123	if (retval)
124		goto cleanup;
125	if (io_options &&
126	    (retval = io_channel_set_options(fs->io, io_options)))
127		goto cleanup;
128	fs->image_io = fs->io;
129	fs->io->app_data = fs;
130	retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
131	if (retval)
132		goto cleanup;
133	if (flags & EXT2_FLAG_IMAGE_FILE) {
134		retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
135					&fs->image_header);
136		if (retval)
137			goto cleanup;
138		retval = io_channel_read_blk(fs->io, 0,
139					     -(int)sizeof(struct ext2_image_hdr),
140					     fs->image_header);
141		if (retval)
142			goto cleanup;
143		if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
144			return EXT2_ET_MAGIC_E2IMAGE;
145		superblock = 1;
146		block_size = fs->image_header->fs_blocksize;
147	}
148
149	/*
150	 * If the user specifies a specific block # for the
151	 * superblock, then he/she must also specify the block size!
152	 * Otherwise, read the master superblock located at offset
153	 * SUPERBLOCK_OFFSET from the start of the partition.
154	 *
155	 * Note: we only save a backup copy of the superblock if we
156	 * are reading the superblock from the primary superblock location.
157	 */
158	if (superblock) {
159		if (!block_size) {
160			retval = EXT2_ET_INVALID_ARGUMENT;
161			goto cleanup;
162		}
163		io_channel_set_blksize(fs->io, block_size);
164		group_block = superblock;
165		fs->orig_super = 0;
166	} else {
167		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
168		superblock = 1;
169		group_block = 0;
170		retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
171		if (retval)
172			goto cleanup;
173	}
174	retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
175				     fs->super);
176	if (retval)
177		goto cleanup;
178	if (fs->orig_super)
179		memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
180
181#ifdef WORDS_BIGENDIAN
182	fs->flags |= EXT2_FLAG_SWAP_BYTES;
183	ext2fs_swap_super(fs->super);
184#else
185	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
186		retval = EXT2_ET_UNIMPLEMENTED;
187		goto cleanup;
188	}
189#endif
190
191	if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
192		retval = EXT2_ET_BAD_MAGIC;
193		goto cleanup;
194	}
195	if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
196		retval = EXT2_ET_REV_TOO_HIGH;
197		goto cleanup;
198	}
199
200	/*
201	 * Check for feature set incompatibility
202	 */
203	if (!(flags & EXT2_FLAG_FORCE)) {
204		features = fs->super->s_feature_incompat;
205#ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
206		if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
207			features &= !EXT2_LIB_SOFTSUPP_INCOMPAT;
208#endif
209		if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
210			retval = EXT2_ET_UNSUPP_FEATURE;
211			goto cleanup;
212		}
213
214		features = fs->super->s_feature_ro_compat;
215#ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
216		if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
217			features &= !EXT2_LIB_SOFTSUPP_RO_COMPAT;
218#endif
219		if ((flags & EXT2_FLAG_RW) &&
220		    (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
221			retval = EXT2_ET_RO_UNSUPP_FEATURE;
222			goto cleanup;
223		}
224
225		if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
226		    (fs->super->s_feature_incompat &
227		     EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
228			retval = EXT2_ET_UNSUPP_FEATURE;
229			goto cleanup;
230		}
231	}
232
233	fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
234	if (fs->blocksize == 0) {
235		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
236		goto cleanup;
237	}
238	fs->fragsize = EXT2_FRAG_SIZE(fs->super);
239	fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
240				       EXT2_INODE_SIZE(fs->super) +
241				       EXT2_BLOCK_SIZE(fs->super) - 1) /
242				      EXT2_BLOCK_SIZE(fs->super));
243	if (block_size) {
244		if (block_size != fs->blocksize) {
245			retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
246			goto cleanup;
247		}
248	}
249	/*
250	 * Set the blocksize to the filesystem's blocksize.
251	 */
252	io_channel_set_blksize(fs->io, fs->blocksize);
253
254	/*
255	 * If this is an external journal device, don't try to read
256	 * the group descriptors, because they're not there.
257	 */
258	if (fs->super->s_feature_incompat &
259	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
260		fs->group_desc_count = 0;
261		*ret_fs = fs;
262		return 0;
263	}
264
265	/*
266	 * Read group descriptors
267	 */
268	blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
269	if (blocks_per_group == 0 ||
270	    blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
271	    fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super)) {
272		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
273		goto cleanup;
274	}
275	fs->group_desc_count = ext2fs_div_ceil(fs->super->s_blocks_count -
276					       fs->super->s_first_data_block,
277					       blocks_per_group);
278	fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
279					  EXT2_DESC_PER_BLOCK(fs->super));
280	retval = ext2fs_get_mem(fs->desc_blocks * fs->blocksize,
281				&fs->group_desc);
282	if (retval)
283		goto cleanup;
284	if (!group_block)
285		group_block = fs->super->s_first_data_block;
286	dest = (char *) fs->group_desc;
287	groups_per_block = fs->blocksize / sizeof(struct ext2_group_desc);
288	for (i=0 ; i < fs->desc_blocks; i++) {
289		blk = ext2fs_descriptor_block_loc(fs, group_block, i);
290		retval = io_channel_read_blk(fs->io, blk, 1, dest);
291		if (retval)
292			goto cleanup;
293#ifdef WORDS_BIGENDIAN
294		gdp = (struct ext2_group_desc *) dest;
295		for (j=0; j < groups_per_block; j++)
296			ext2fs_swap_group_desc(gdp++);
297#endif
298		dest += fs->blocksize;
299	}
300
301	fs->stride = fs->super->s_raid_stride;
302
303	*ret_fs = fs;
304	return 0;
305cleanup:
306	ext2fs_free(fs);
307	return retval;
308}
309
310/*
311 * Set/get the filesystem data I/O channel.
312 *
313 * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
314 */
315errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
316{
317	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
318		return EXT2_ET_NOT_IMAGE_FILE;
319	if (old_io) {
320		*old_io = (fs->image_io == fs->io) ? 0 : fs->io;
321	}
322	return 0;
323}
324
325errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
326{
327	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
328		return EXT2_ET_NOT_IMAGE_FILE;
329	fs->io = new_io ? new_io : fs->image_io;
330	return 0;
331}
332
333errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
334{
335	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
336		return EXT2_ET_NOT_IMAGE_FILE;
337	fs->io = fs->image_io = new_io;
338	fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
339		EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
340	fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
341	return 0;
342}
343