source: branches/stable/mindi-busybox/e2fsprogs/ext2fs/openfs.c @ 821

Last change on this file since 821 was 821, checked in by Bruno Cornec, 14 years ago

Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)

File size: 8.7 KB
Line 
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    int     groups_per_block, blocks_per_group;
90    blk_t       group_block, blk;
91    char        *dest, *cp;
92#if BB_BIG_ENDIAN
93    int j;
94    struct ext2_group_desc *gdp;
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    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    retval = manager->open(fs->device_name,
118                   (flags & EXT2_FLAG_RW) ? IO_FLAG_RW : 0,
119                   &fs->io);
120    if (retval)
121        goto cleanup;
122    if (io_options &&
123        (retval = io_channel_set_options(fs->io, io_options)))
124        goto cleanup;
125    fs->image_io = fs->io;
126    fs->io->app_data = fs;
127    retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
128    if (retval)
129        goto cleanup;
130    if (flags & EXT2_FLAG_IMAGE_FILE) {
131        retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
132                    &fs->image_header);
133        if (retval)
134            goto cleanup;
135        retval = io_channel_read_blk(fs->io, 0,
136                         -(int)sizeof(struct ext2_image_hdr),
137                         fs->image_header);
138        if (retval)
139            goto cleanup;
140        if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
141            return EXT2_ET_MAGIC_E2IMAGE;
142        superblock = 1;
143        block_size = fs->image_header->fs_blocksize;
144    }
145
146    /*
147     * If the user specifies a specific block # for the
148     * superblock, then he/she must also specify the block size!
149     * Otherwise, read the master superblock located at offset
150     * SUPERBLOCK_OFFSET from the start of the partition.
151     *
152     * Note: we only save a backup copy of the superblock if we
153     * are reading the superblock from the primary superblock location.
154     */
155    if (superblock) {
156        if (!block_size) {
157            retval = EXT2_ET_INVALID_ARGUMENT;
158            goto cleanup;
159        }
160        io_channel_set_blksize(fs->io, block_size);
161        group_block = superblock;
162        fs->orig_super = 0;
163    } else {
164        io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
165        superblock = 1;
166        group_block = 0;
167        retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
168        if (retval)
169            goto cleanup;
170    }
171    retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
172                     fs->super);
173    if (retval)
174        goto cleanup;
175    if (fs->orig_super)
176        memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
177
178#if BB_BIG_ENDIAN
179    if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) ||
180        (fs->flags & EXT2_FLAG_SWAP_BYTES)) {
181        fs->flags |= EXT2_FLAG_SWAP_BYTES;
182
183        ext2fs_swap_super(fs->super);
184    }
185#endif
186
187    if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
188        retval = EXT2_ET_BAD_MAGIC;
189        goto cleanup;
190    }
191    if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
192        retval = EXT2_ET_REV_TOO_HIGH;
193        goto cleanup;
194    }
195
196    /*
197     * Check for feature set incompatibility
198     */
199    if (!(flags & EXT2_FLAG_FORCE)) {
200        if (fs->super->s_feature_incompat &
201            ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
202            retval = EXT2_ET_UNSUPP_FEATURE;
203            goto cleanup;
204        }
205        if ((flags & EXT2_FLAG_RW) &&
206            (fs->super->s_feature_ro_compat &
207             ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
208            retval = EXT2_ET_RO_UNSUPP_FEATURE;
209            goto cleanup;
210        }
211        if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
212            (fs->super->s_feature_incompat &
213             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
214            retval = EXT2_ET_UNSUPP_FEATURE;
215            goto cleanup;
216        }
217    }
218
219    fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
220    if (fs->blocksize == 0) {
221        retval = EXT2_ET_CORRUPT_SUPERBLOCK;
222        goto cleanup;
223    }
224    fs->fragsize = EXT2_FRAG_SIZE(fs->super);
225    fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
226                       EXT2_INODE_SIZE(fs->super) +
227                       EXT2_BLOCK_SIZE(fs->super) - 1) /
228                      EXT2_BLOCK_SIZE(fs->super));
229    if (block_size) {
230        if (block_size != fs->blocksize) {
231            retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
232            goto cleanup;
233        }
234    }
235    /*
236     * Set the blocksize to the filesystem's blocksize.
237     */
238    io_channel_set_blksize(fs->io, fs->blocksize);
239
240    /*
241     * If this is an external journal device, don't try to read
242     * the group descriptors, because they're not there.
243     */
244    if (fs->super->s_feature_incompat &
245        EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
246        fs->group_desc_count = 0;
247        *ret_fs = fs;
248        return 0;
249    }
250
251    /*
252     * Read group descriptors
253     */
254    blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
255    if (blocks_per_group == 0 ||
256        blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
257        fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super)) {
258        retval = EXT2_ET_CORRUPT_SUPERBLOCK;
259        goto cleanup;
260    }
261    fs->group_desc_count = (fs->super->s_blocks_count -
262                fs->super->s_first_data_block +
263                blocks_per_group - 1) / blocks_per_group;
264    fs->desc_blocks = (fs->group_desc_count +
265               EXT2_DESC_PER_BLOCK(fs->super) - 1)
266        / EXT2_DESC_PER_BLOCK(fs->super);
267    retval = ext2fs_get_mem(fs->desc_blocks * fs->blocksize,
268                &fs->group_desc);
269    if (retval)
270        goto cleanup;
271    if (!group_block)
272        group_block = fs->super->s_first_data_block;
273    dest = (char *) fs->group_desc;
274    groups_per_block = fs->blocksize / sizeof(struct ext2_group_desc);
275    for (i=0 ; i < fs->desc_blocks; i++) {
276        blk = ext2fs_descriptor_block_loc(fs, group_block, i);
277        retval = io_channel_read_blk(fs->io, blk, 1, dest);
278        if (retval)
279            goto cleanup;
280#if BB_BIG_ENDIAN
281        if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
282            gdp = (struct ext2_group_desc *) dest;
283            for (j=0; j < groups_per_block; j++)
284                ext2fs_swap_group_desc(gdp++);
285        }
286#endif
287        dest += fs->blocksize;
288    }
289
290    *ret_fs = fs;
291    return 0;
292cleanup:
293    ext2fs_free(fs);
294    return retval;
295}
296
297/*
298 * Set/get the filesystem data I/O channel.
299 *
300 * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
301 */
302errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
303{
304    if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
305        return EXT2_ET_NOT_IMAGE_FILE;
306    if (old_io) {
307        *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
308    }
309    return 0;
310}
311
312errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
313{
314    if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
315        return EXT2_ET_NOT_IMAGE_FILE;
316    fs->io = new_io ? new_io : fs->image_io;
317    return 0;
318}
319
320errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
321{
322    if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
323        return EXT2_ET_NOT_IMAGE_FILE;
324    fs->io = fs->image_io = new_io;
325    fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
326        EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
327    fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
328    return 0;
329}
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