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      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 
     32 blk_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 
     61 errcode_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  */
     80 errcode_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 	retval = manager->open(fs->device_name, io_flags, &fs->io);
    125 	if (retval)
    126 		goto cleanup;
    127 	if (io_options &&
    128 	    (retval = io_channel_set_options(fs->io, io_options)))
    129 		goto cleanup;
    130 	fs->image_io = fs->io;
    131 	fs->io->app_data = fs;
    132 	retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
    133 	if (retval)
    134 		goto cleanup;
    135 	if (flags & EXT2_FLAG_IMAGE_FILE) {
    136 		retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
    137 					&fs->image_header);
    138 		if (retval)
    139 			goto cleanup;
    140 		retval = io_channel_read_blk(fs->io, 0,
    141 					     -(int)sizeof(struct ext2_image_hdr),
    142 					     fs->image_header);
    143 		if (retval)
    144 			goto cleanup;
    145 		if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
    146 			return EXT2_ET_MAGIC_E2IMAGE;
    147 		superblock = 1;
    148 		block_size = fs->image_header->fs_blocksize;
    149 	}
    150 
    151 	/*
    152 	 * If the user specifies a specific block # for the
    153 	 * superblock, then he/she must also specify the block size!
    154 	 * Otherwise, read the master superblock located at offset
    155 	 * SUPERBLOCK_OFFSET from the start of the partition.
    156 	 *
    157 	 * Note: we only save a backup copy of the superblock if we
    158 	 * are reading the superblock from the primary superblock location.
    159 	 */
    160 	if (superblock) {
    161 		if (!block_size) {
    162 			retval = EXT2_ET_INVALID_ARGUMENT;
    163 			goto cleanup;
    164 		}
    165 		io_channel_set_blksize(fs->io, block_size);
    166 		group_block = superblock;
    167 		fs->orig_super = 0;
    168 	} else {
    169 		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
    170 		superblock = 1;
    171 		group_block = 0;
    172 		retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
    173 		if (retval)
    174 			goto cleanup;
    175 	}
    176 	retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
    177 				     fs->super);
    178 	if (retval)
    179 		goto cleanup;
    180 	if (fs->orig_super)
    181 		memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
    182 
    183 #ifdef WORDS_BIGENDIAN
    184 	fs->flags |= EXT2_FLAG_SWAP_BYTES;
    185 	ext2fs_swap_super(fs->super);
    186 #else
    187 	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
    188 		retval = EXT2_ET_UNIMPLEMENTED;
    189 		goto cleanup;
    190 	}
    191 #endif
    192 
    193 	if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
    194 		retval = EXT2_ET_BAD_MAGIC;
    195 		goto cleanup;
    196 	}
    197 	if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
    198 		retval = EXT2_ET_REV_TOO_HIGH;
    199 		goto cleanup;
    200 	}
    201 
    202 	/*
    203 	 * Check for feature set incompatibility
    204 	 */
    205 	if (!(flags & EXT2_FLAG_FORCE)) {
    206 		features = fs->super->s_feature_incompat;
    207 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
    208 		if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
    209 			features &= !EXT2_LIB_SOFTSUPP_INCOMPAT;
    210 #endif
    211 		if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
    212 			retval = EXT2_ET_UNSUPP_FEATURE;
    213 			goto cleanup;
    214 		}
    215 
    216 		features = fs->super->s_feature_ro_compat;
    217 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
    218 		if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
    219 			features &= !EXT2_LIB_SOFTSUPP_RO_COMPAT;
    220 #endif
    221 		if ((flags & EXT2_FLAG_RW) &&
    222 		    (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
    223 			retval = EXT2_ET_RO_UNSUPP_FEATURE;
    224 			goto cleanup;
    225 		}
    226 
    227 		if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
    228 		    (fs->super->s_feature_incompat &
    229 		     EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
    230 			retval = EXT2_ET_UNSUPP_FEATURE;
    231 			goto cleanup;
    232 		}
    233 	}
    234 
    235 	if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
    236 	    EXT2_MAX_BLOCK_LOG_SIZE) {
    237 		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
    238 		goto cleanup;
    239 	}
    240 	fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
    241 	if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
    242 		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
    243 		goto cleanup;
    244 	}
    245 	fs->fragsize = EXT2_FRAG_SIZE(fs->super);
    246 	fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
    247 				       EXT2_INODE_SIZE(fs->super) +
    248 				       EXT2_BLOCK_SIZE(fs->super) - 1) /
    249 				      EXT2_BLOCK_SIZE(fs->super));
    250 	if (block_size) {
    251 		if (block_size != fs->blocksize) {
    252 			retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
    253 			goto cleanup;
    254 		}
    255 	}
    256 	/*
    257 	 * Set the blocksize to the filesystem's blocksize.
    258 	 */
    259 	io_channel_set_blksize(fs->io, fs->blocksize);
    260 
    261 	/*
    262 	 * If this is an external journal device, don't try to read
    263 	 * the group descriptors, because they're not there.
    264 	 */
    265 	if (fs->super->s_feature_incompat &
    266 	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
    267 		fs->group_desc_count = 0;
    268 		*ret_fs = fs;
    269 		return 0;
    270 	}
    271 
    272 	if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
    273 		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
    274 		goto cleanup;
    275 	}
    276 
    277 	/*
    278 	 * Read group descriptors
    279 	 */
    280 	blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
    281 	if (blocks_per_group == 0 ||
    282 	    blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
    283 	    fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
    284            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
    285            fs->super->s_first_data_block >= fs->super->s_blocks_count) {
    286 		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
    287 		goto cleanup;
    288 	}
    289 	fs->group_desc_count = ext2fs_div_ceil(fs->super->s_blocks_count -
    290 					       fs->super->s_first_data_block,
    291 					       blocks_per_group);
    292        if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
    293            fs->super->s_inodes_count) {
    294                retval = EXT2_ET_CORRUPT_SUPERBLOCK;
    295 		goto cleanup;
    296        }
    297 	fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
    298 					  EXT2_DESC_PER_BLOCK(fs->super));
    299 	retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
    300 				&fs->group_desc);
    301 	if (retval)
    302 		goto cleanup;
    303 	if (!group_block)
    304 		group_block = fs->super->s_first_data_block;
    305 	dest = (char *) fs->group_desc;
    306 	groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
    307 	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
    308 		first_meta_bg = fs->super->s_first_meta_bg;
    309 	else
    310 		first_meta_bg = fs->desc_blocks;
    311 	if (first_meta_bg) {
    312 		retval = io_channel_read_blk(fs->io, group_block+1,
    313 					     first_meta_bg, dest);
    314 		if (retval)
    315 			goto cleanup;
    316 #ifdef WORDS_BIGENDIAN
    317 		gdp = (struct ext2_group_desc *) dest;
    318 		for (j=0; j < groups_per_block*first_meta_bg; j++)
    319 			ext2fs_swap_group_desc(gdp++);
    320 #endif
    321 		dest += fs->blocksize*first_meta_bg;
    322 	}
    323 	for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
    324 		blk = ext2fs_descriptor_block_loc(fs, group_block, i);
    325 		retval = io_channel_read_blk(fs->io, blk, 1, dest);
    326 		if (retval)
    327 			goto cleanup;
    328 #ifdef WORDS_BIGENDIAN
    329 		gdp = (struct ext2_group_desc *) dest;
    330 		for (j=0; j < groups_per_block; j++)
    331 			ext2fs_swap_group_desc(gdp++);
    332 #endif
    333 		dest += fs->blocksize;
    334 	}
    335 
    336 	fs->stride = fs->super->s_raid_stride;
    337 
    338 	/*
    339 	 * If recovery is from backup superblock, Clear _UNININT flags &
    340 	 * reset bg_itable_unused to zero
    341 	 */
    342 	if (superblock > 1 && EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
    343 					EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
    344 		struct ext2_group_desc *gd;
    345 		for (i = 0, gd = fs->group_desc; i < fs->group_desc_count;
    346 		     i++, gd++) {
    347 			gd->bg_flags &= ~EXT2_BG_BLOCK_UNINIT;
    348 			gd->bg_flags &= ~EXT2_BG_INODE_UNINIT;
    349 			gd->bg_itable_unused = 0;
    350 		}
    351 		ext2fs_mark_super_dirty(fs);
    352 	}
    353 
    354 	fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
    355 	*ret_fs = fs;
    356 	return 0;
    357 cleanup:
    358 	if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
    359 		*ret_fs = fs;
    360 	else
    361 		ext2fs_free(fs);
    362 	return retval;
    363 }
    364 
    365 /*
    366  * Set/get the filesystem data I/O channel.
    367  *
    368  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
    369  */
    370 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
    371 {
    372 	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
    373 		return EXT2_ET_NOT_IMAGE_FILE;
    374 	if (old_io) {
    375 		*old_io = (fs->image_io == fs->io) ? 0 : fs->io;
    376 	}
    377 	return 0;
    378 }
    379 
    380 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
    381 {
    382 	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
    383 		return EXT2_ET_NOT_IMAGE_FILE;
    384 	fs->io = new_io ? new_io : fs->image_io;
    385 	return 0;
    386 }
    387 
    388 errcode_t ext2fs_rewrite_to_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 = fs->image_io = new_io;
    393 	fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
    394 		EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
    395 	fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
    396 	return 0;
    397 }
    398