openfs.c revision 6220b6715f4900bbcfa04ef3b81ccf48b2d21825 
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 Library
8 * General Public License, version 2.
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 = EXT2_DESC_PER_BLOCK(fs->super) * i;
43	if (ext2fs_bg_has_super(fs, bg))
44		has_super = 1;
45	ret_blk = ext2fs_group_first_block(fs, bg) + has_super;
46	/*
47	 * If group_block is not the normal value, we're trying to use
48	 * the backup group descriptors and superblock --- so use the
49	 * alternate location of the second block group in the
50	 * metablock group.  Ideally we should be testing each bg
51	 * descriptor block individually for correctness, but we don't
52	 * have the infrastructure in place to do that.
53	 */
54	if (group_block != fs->super->s_first_data_block &&
55	    ((ret_blk + fs->super->s_blocks_per_group) <
56	     fs->super->s_blocks_count))
57		ret_blk += fs->super->s_blocks_per_group;
58	return ret_blk;
59}
60
61errcode_t ext2fs_open(const char *name, int flags, int superblock,
62		      unsigned int block_size, io_manager manager,
63		      ext2_filsys *ret_fs)
64{
65	return ext2fs_open2(name, 0, flags, superblock, block_size,
66			    manager, ret_fs);
67}
68
69/*
70 *  Note: if superblock is non-zero, block-size must also be non-zero.
71 * 	Superblock and block_size can be zero to use the default size.
72 *
73 * Valid flags for ext2fs_open()
74 *
75 * 	EXT2_FLAG_RW	- Open the filesystem for read/write.
76 * 	EXT2_FLAG_FORCE - Open the filesystem even if some of the
77 *				features aren't supported.
78 *	EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
79 */
80errcode_t ext2fs_open2(const char *name, const char *io_options,
81		       int flags, int superblock,
82		       unsigned int block_size, io_manager manager,
83		       ext2_filsys *ret_fs)
84{
85	ext2_filsys	fs;
86	errcode_t	retval;
87	unsigned long	i, first_meta_bg;
88	__u32		features;
89	int		groups_per_block, blocks_per_group, io_flags;
90	blk_t		group_block, blk;
91	char		*dest, *cp;
92#ifdef WORDS_BIGENDIAN
93	struct ext2_group_desc *gdp;
94	int		j;
95#endif
96
97	EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
98
99	retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
100	if (retval)
101		return retval;
102
103	memset(fs, 0, sizeof(struct struct_ext2_filsys));
104	fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
105	fs->flags = flags;
106	/* don't overwrite sb backups unless flag is explicitly cleared */
107	fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
108	fs->umask = 022;
109	retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
110	if (retval)
111		goto cleanup;
112	strcpy(fs->device_name, name);
113	cp = strchr(fs->device_name, '?');
114	if (!io_options && cp) {
115		*cp++ = 0;
116		io_options = cp;
117	}
118
119	io_flags = 0;
120	if (flags & EXT2_FLAG_RW)
121		io_flags |= IO_FLAG_RW;
122	if (flags & EXT2_FLAG_EXCLUSIVE)
123		io_flags |= IO_FLAG_EXCLUSIVE;
124	if (flags & EXT2_FLAG_DIRECT_IO)
125		io_flags |= IO_FLAG_DIRECT_IO;
126	retval = manager->open(fs->device_name, io_flags, &fs->io);
127	if (retval)
128		goto cleanup;
129	if (io_options &&
130	    (retval = io_channel_set_options(fs->io, io_options)))
131		goto cleanup;
132	fs->image_io = fs->io;
133	fs->io->app_data = fs;
134	retval = ext2fs_get_memalign(SUPERBLOCK_SIZE, 512, &fs->super);
135	if (retval)
136		goto cleanup;
137	if (flags & EXT2_FLAG_IMAGE_FILE) {
138		retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
139					&fs->image_header);
140		if (retval)
141			goto cleanup;
142		retval = io_channel_read_blk(fs->io, 0,
143					     -(int)sizeof(struct ext2_image_hdr),
144					     fs->image_header);
145		if (retval)
146			goto cleanup;
147		if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
148			return EXT2_ET_MAGIC_E2IMAGE;
149		superblock = 1;
150		block_size = fs->image_header->fs_blocksize;
151	}
152
153	/*
154	 * If the user specifies a specific block # for the
155	 * superblock, then he/she must also specify the block size!
156	 * Otherwise, read the master superblock located at offset
157	 * SUPERBLOCK_OFFSET from the start of the partition.
158	 *
159	 * Note: we only save a backup copy of the superblock if we
160	 * are reading the superblock from the primary superblock location.
161	 */
162	if (superblock) {
163		if (!block_size) {
164			retval = EXT2_ET_INVALID_ARGUMENT;
165			goto cleanup;
166		}
167		io_channel_set_blksize(fs->io, block_size);
168		group_block = superblock;
169		fs->orig_super = 0;
170	} else {
171		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
172		superblock = 1;
173		group_block = 0;
174		retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
175		if (retval)
176			goto cleanup;
177	}
178	retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
179				     fs->super);
180	if (retval)
181		goto cleanup;
182	if (fs->orig_super)
183		memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
184
185#ifdef WORDS_BIGENDIAN
186	fs->flags |= EXT2_FLAG_SWAP_BYTES;
187	ext2fs_swap_super(fs->super);
188#else
189	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
190		retval = EXT2_ET_UNIMPLEMENTED;
191		goto cleanup;
192	}
193#endif
194
195	if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
196		retval = EXT2_ET_BAD_MAGIC;
197		goto cleanup;
198	}
199	if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
200		retval = EXT2_ET_REV_TOO_HIGH;
201		goto cleanup;
202	}
203
204	/*
205	 * Check for feature set incompatibility
206	 */
207	if (!(flags & EXT2_FLAG_FORCE)) {
208		features = fs->super->s_feature_incompat;
209#ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
210		if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
211			features &= !EXT2_LIB_SOFTSUPP_INCOMPAT;
212#endif
213		if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
214			retval = EXT2_ET_UNSUPP_FEATURE;
215			goto cleanup;
216		}
217
218		features = fs->super->s_feature_ro_compat;
219#ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
220		if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
221			features &= !EXT2_LIB_SOFTSUPP_RO_COMPAT;
222#endif
223		if ((flags & EXT2_FLAG_RW) &&
224		    (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
225			retval = EXT2_ET_RO_UNSUPP_FEATURE;
226			goto cleanup;
227		}
228
229		if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
230		    (fs->super->s_feature_incompat &
231		     EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
232			retval = EXT2_ET_UNSUPP_FEATURE;
233			goto cleanup;
234		}
235	}
236
237	if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
238	    EXT2_MAX_BLOCK_LOG_SIZE) {
239		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
240		goto cleanup;
241	}
242	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
243					EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
244	    (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
245		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
246		goto cleanup;
247	}
248	fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
249	if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
250		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
251		goto cleanup;
252	}
253	fs->clustersize = EXT2_CLUSTER_SIZE(fs->super);
254	fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
255				       EXT2_INODE_SIZE(fs->super) +
256				       EXT2_BLOCK_SIZE(fs->super) - 1) /
257				      EXT2_BLOCK_SIZE(fs->super));
258	if (block_size) {
259		if (block_size != fs->blocksize) {
260			retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
261			goto cleanup;
262		}
263	}
264	/*
265	 * Set the blocksize to the filesystem's blocksize.
266	 */
267	io_channel_set_blksize(fs->io, fs->blocksize);
268
269	/*
270	 * If this is an external journal device, don't try to read
271	 * the group descriptors, because they're not there.
272	 */
273	if (fs->super->s_feature_incompat &
274	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
275		fs->group_desc_count = 0;
276		*ret_fs = fs;
277		return 0;
278	}
279
280	if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
281		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
282		goto cleanup;
283	}
284
285	/*
286	 * Read group descriptors
287	 */
288	blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
289	if (blocks_per_group == 0 ||
290	    blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
291	    fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
292           EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
293           fs->super->s_first_data_block >= fs->super->s_blocks_count) {
294		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
295		goto cleanup;
296	}
297	fs->group_desc_count = ext2fs_div_ceil(fs->super->s_blocks_count -
298					       fs->super->s_first_data_block,
299					       blocks_per_group);
300       if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
301           fs->super->s_inodes_count) {
302               retval = EXT2_ET_CORRUPT_SUPERBLOCK;
303		goto cleanup;
304       }
305	fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
306					  EXT2_DESC_PER_BLOCK(fs->super));
307	retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
308				&fs->group_desc);
309	if (retval)
310		goto cleanup;
311	if (!group_block)
312		group_block = fs->super->s_first_data_block;
313	dest = (char *) fs->group_desc;
314	groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
315	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
316		first_meta_bg = fs->super->s_first_meta_bg;
317	else
318		first_meta_bg = fs->desc_blocks;
319	if (first_meta_bg) {
320		retval = io_channel_read_blk(fs->io, group_block+1,
321					     first_meta_bg, dest);
322		if (retval)
323			goto cleanup;
324#ifdef WORDS_BIGENDIAN
325		gdp = (struct ext2_group_desc *) dest;
326		for (j=0; j < groups_per_block*first_meta_bg; j++)
327			ext2fs_swap_group_desc(gdp++);
328#endif
329		dest += fs->blocksize*first_meta_bg;
330	}
331	for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
332		blk = ext2fs_descriptor_block_loc(fs, group_block, i);
333		retval = io_channel_read_blk(fs->io, blk, 1, dest);
334		if (retval)
335			goto cleanup;
336#ifdef WORDS_BIGENDIAN
337		gdp = (struct ext2_group_desc *) dest;
338		for (j=0; j < groups_per_block; j++)
339			ext2fs_swap_group_desc(gdp++);
340#endif
341		dest += fs->blocksize;
342	}
343
344	fs->stride = fs->super->s_raid_stride;
345
346	/*
347	 * If recovery is from backup superblock, Clear _UNININT flags &
348	 * reset bg_itable_unused to zero
349	 */
350	if (superblock > 1 && EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
351					EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
352		struct ext2_group_desc *gd;
353		for (i = 0, gd = fs->group_desc; i < fs->group_desc_count;
354		     i++, gd++) {
355			gd->bg_flags &= ~EXT2_BG_BLOCK_UNINIT;
356			gd->bg_flags &= ~EXT2_BG_INODE_UNINIT;
357			gd->bg_itable_unused = 0;
358		}
359		ext2fs_mark_super_dirty(fs);
360	}
361
362	fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
363	*ret_fs = fs;
364	return 0;
365cleanup:
366	if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
367		*ret_fs = fs;
368	else
369		ext2fs_free(fs);
370	return retval;
371}
372
373/*
374 * Set/get the filesystem data I/O channel.
375 *
376 * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
377 */
378errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
379{
380	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
381		return EXT2_ET_NOT_IMAGE_FILE;
382	if (old_io) {
383		*old_io = (fs->image_io == fs->io) ? 0 : fs->io;
384	}
385	return 0;
386}
387
388errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
389{
390	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
391		return EXT2_ET_NOT_IMAGE_FILE;
392	fs->io = new_io ? new_io : fs->image_io;
393	return 0;
394}
395
396errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
397{
398	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
399		return EXT2_ET_NOT_IMAGE_FILE;
400	fs->io = fs->image_io = new_io;
401	fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
402		EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
403	fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
404	return 0;
405}
406