Annotation of /trunk/mkinitrd-magellan/klibc/usr/kinit/fstype/fstype.c
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Revision 815 -
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Fri Apr 24 18:32:46 2009 UTC (15 years, 5 months ago) by niro
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File size: 13334 byte(s)
Fri Apr 24 18:32:46 2009 UTC (15 years, 5 months ago) by niro
File MIME type: text/plain
File size: 13334 byte(s)
-updated to klibc-1.5.15
1 | niro | 532 | /* |
2 | * by rmk | ||
3 | * | ||
4 | * Detect filesystem type (on stdin) and output strings for two | ||
5 | * environment variables: | ||
6 | * FSTYPE - filesystem type | ||
7 | * FSSIZE - filesystem size (if known) | ||
8 | * | ||
9 | * We currently detect the filesystems listed below in the struct | ||
10 | * "imagetype images" (in the order they are listed). | ||
11 | */ | ||
12 | |||
13 | #include <sys/types.h> | ||
14 | #include <stdio.h> | ||
15 | niro | 815 | #include <ctype.h> |
16 | niro | 532 | #include <string.h> |
17 | #include <unistd.h> | ||
18 | #include <fcntl.h> | ||
19 | #include <endian.h> | ||
20 | #include <netinet/in.h> | ||
21 | niro | 815 | #include <sys/utsname.h> |
22 | niro | 532 | #include <sys/vfs.h> |
23 | |||
24 | #define cpu_to_be32(x) __cpu_to_be32(x) /* Needed by romfs_fs.h */ | ||
25 | |||
26 | #include "romfs_fs.h" | ||
27 | #include "cramfs_fs.h" | ||
28 | #include "minix_fs.h" | ||
29 | #include "ext2_fs.h" | ||
30 | #include "ext3_fs.h" | ||
31 | #include "xfs_sb.h" | ||
32 | #include "luks_fs.h" | ||
33 | #include "lvm2_sb.h" | ||
34 | #include "iso9660_sb.h" | ||
35 | niro | 815 | #include "squashfs_fs.h" |
36 | #include "gfs2_fs.h" | ||
37 | #include "ocfs2_fs.h" | ||
38 | #include "nilfs_fs.h" | ||
39 | niro | 532 | |
40 | /* | ||
41 | * Slightly cleaned up version of jfs_superblock to | ||
42 | * avoid pulling in other kernel header files. | ||
43 | */ | ||
44 | #include "jfs_superblock.h" | ||
45 | |||
46 | /* | ||
47 | * reiserfs_fs.h is too sick to include directly. | ||
48 | * Use a cleaned up version. | ||
49 | */ | ||
50 | #include "reiserfs_fs.h" | ||
51 | niro | 815 | #include "reiser4_fs.h" |
52 | niro | 532 | |
53 | #include "fstype.h" | ||
54 | |||
55 | #define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0])) | ||
56 | |||
57 | #define BLOCK_SIZE 1024 | ||
58 | |||
59 | /* Swap needs the definition of block size */ | ||
60 | #include "swap_fs.h" | ||
61 | |||
62 | static int gzip_image(const void *buf, unsigned long long *bytes) | ||
63 | { | ||
64 | const unsigned char *p = buf; | ||
65 | |||
66 | if (p[0] == 037 && (p[1] == 0213 || p[1] == 0236)) { | ||
67 | /* The length of a gzip stream can only be determined | ||
68 | by processing the whole stream */ | ||
69 | *bytes = 0ULL; | ||
70 | return 1; | ||
71 | } | ||
72 | return 0; | ||
73 | } | ||
74 | |||
75 | static int cramfs_image(const void *buf, unsigned long long *bytes) | ||
76 | { | ||
77 | const struct cramfs_super *sb = (const struct cramfs_super *)buf; | ||
78 | |||
79 | if (sb->magic == CRAMFS_MAGIC) { | ||
80 | if (sb->flags & CRAMFS_FLAG_FSID_VERSION_2) | ||
81 | *bytes = (unsigned long long)sb->fsid.blocks << 10; | ||
82 | else | ||
83 | *bytes = 0; | ||
84 | return 1; | ||
85 | } | ||
86 | return 0; | ||
87 | } | ||
88 | |||
89 | static int romfs_image(const void *buf, unsigned long long *bytes) | ||
90 | { | ||
91 | const struct romfs_super_block *sb = | ||
92 | (const struct romfs_super_block *)buf; | ||
93 | |||
94 | if (sb->word0 == ROMSB_WORD0 && sb->word1 == ROMSB_WORD1) { | ||
95 | *bytes = __be32_to_cpu(sb->size); | ||
96 | return 1; | ||
97 | } | ||
98 | return 0; | ||
99 | } | ||
100 | |||
101 | static int minix_image(const void *buf, unsigned long long *bytes) | ||
102 | { | ||
103 | const struct minix_super_block *sb = | ||
104 | (const struct minix_super_block *)buf; | ||
105 | |||
106 | if (sb->s_magic == MINIX_SUPER_MAGIC || | ||
107 | sb->s_magic == MINIX_SUPER_MAGIC2) { | ||
108 | *bytes = (unsigned long long)sb->s_nzones | ||
109 | << (sb->s_log_zone_size + 10); | ||
110 | return 1; | ||
111 | } | ||
112 | return 0; | ||
113 | } | ||
114 | |||
115 | niro | 815 | /* |
116 | * Check to see if a filesystem is in /proc/filesystems. | ||
117 | * Returns 1 if found, 0 if not | ||
118 | */ | ||
119 | static int fs_proc_check(const char *fs_name) | ||
120 | { | ||
121 | FILE *f; | ||
122 | char buf[80], *cp, *t; | ||
123 | |||
124 | f = fopen("/proc/filesystems", "r"); | ||
125 | if (!f) | ||
126 | return (0); | ||
127 | while (fgets(buf, sizeof(buf), f)) { | ||
128 | cp = buf; | ||
129 | if (!isspace(*cp)) { | ||
130 | while (*cp && !isspace(*cp)) | ||
131 | cp++; | ||
132 | } | ||
133 | while (*cp && isspace(*cp)) | ||
134 | cp++; | ||
135 | if ((t = strchr(cp, '\n')) != NULL) | ||
136 | *t = 0; | ||
137 | if ((t = strchr(cp, '\t')) != NULL) | ||
138 | *t = 0; | ||
139 | if ((t = strchr(cp, ' ')) != NULL) | ||
140 | *t = 0; | ||
141 | if (!strcmp(fs_name, cp)) { | ||
142 | fclose(f); | ||
143 | return (1); | ||
144 | } | ||
145 | } | ||
146 | fclose(f); | ||
147 | return (0); | ||
148 | } | ||
149 | |||
150 | /* | ||
151 | * Check to see if a filesystem is available as a module | ||
152 | * Returns 1 if found, 0 if not | ||
153 | */ | ||
154 | static int check_for_modules(const char *fs_name) | ||
155 | { | ||
156 | struct utsname uts; | ||
157 | FILE *f; | ||
158 | char buf[1024], *cp, *t; | ||
159 | int i; | ||
160 | |||
161 | if (uname(&uts)) | ||
162 | return (0); | ||
163 | snprintf(buf, sizeof(buf), "/lib/modules/%s/modules.dep", uts.release); | ||
164 | |||
165 | f = fopen(buf, "r"); | ||
166 | if (!f) | ||
167 | return (0); | ||
168 | while (fgets(buf, sizeof(buf), f)) { | ||
169 | if ((cp = strchr(buf, ':')) != NULL) | ||
170 | *cp = 0; | ||
171 | else | ||
172 | continue; | ||
173 | if ((cp = strrchr(buf, '/')) != NULL) | ||
174 | cp++; | ||
175 | i = strlen(cp); | ||
176 | if (i > 3) { | ||
177 | t = cp + i - 3; | ||
178 | if (!strcmp(t, ".ko")) | ||
179 | *t = 0; | ||
180 | } | ||
181 | if (!strcmp(cp, fs_name)) { | ||
182 | fclose(f); | ||
183 | return (1); | ||
184 | } | ||
185 | } | ||
186 | fclose(f); | ||
187 | return (0); | ||
188 | } | ||
189 | |||
190 | static int base_ext4_image(const void *buf, unsigned long long *bytes, | ||
191 | int *test_fs) | ||
192 | { | ||
193 | const struct ext3_super_block *sb = | ||
194 | (const struct ext3_super_block *)buf; | ||
195 | |||
196 | if (sb->s_magic != __cpu_to_le16(EXT2_SUPER_MAGIC)) | ||
197 | return 0; | ||
198 | |||
199 | /* | ||
200 | * For now, ext4 requires a journal -- but this may change | ||
201 | * soon if we get that patch from Google. :-) | ||
202 | */ | ||
203 | if ((sb->s_feature_compat | ||
204 | & __cpu_to_le32(EXT3_FEATURE_COMPAT_HAS_JOURNAL)) == 0) | ||
205 | return 0; | ||
206 | |||
207 | /* There is at least one feature not supported by ext3 */ | ||
208 | if ((sb->s_feature_incompat | ||
209 | & __cpu_to_le32(EXT3_FEATURE_INCOMPAT_UNSUPPORTED)) || | ||
210 | (sb->s_feature_ro_compat | ||
211 | & __cpu_to_le32(EXT3_FEATURE_RO_COMPAT_UNSUPPORTED))) { | ||
212 | *bytes = (unsigned long long)__le32_to_cpu(sb->s_blocks_count) | ||
213 | << (10 + __le32_to_cpu(sb->s_log_block_size)); | ||
214 | *test_fs = (sb->s_flags & | ||
215 | __cpu_to_le32(EXT2_FLAGS_TEST_FILESYS)) != 0; | ||
216 | return 1; | ||
217 | } | ||
218 | return 0; | ||
219 | } | ||
220 | |||
221 | static int ext4_image(const void *buf, unsigned long long *bytes) | ||
222 | { | ||
223 | int ret, test_fs, ext4dev_present, ext4_present; | ||
224 | |||
225 | ret = base_ext4_image(buf, bytes, &test_fs); | ||
226 | if (ret == 0) | ||
227 | return 0; | ||
228 | ext4dev_present = (fs_proc_check("ext4dev") || | ||
229 | check_for_modules("ext4dev")); | ||
230 | ext4_present = (fs_proc_check("ext4") || check_for_modules("ext4")); | ||
231 | if ((test_fs || !ext4_present) && ext4dev_present) | ||
232 | return 0; | ||
233 | return 1; | ||
234 | } | ||
235 | |||
236 | static int ext4dev_image(const void *buf, unsigned long long *bytes) | ||
237 | { | ||
238 | int ret, test_fs, ext4dev_present, ext4_present; | ||
239 | |||
240 | ret = base_ext4_image(buf, bytes, &test_fs); | ||
241 | if (ret == 0) | ||
242 | return 0; | ||
243 | ext4dev_present = (fs_proc_check("ext4dev") || | ||
244 | check_for_modules("ext4dev")); | ||
245 | ext4_present = (fs_proc_check("ext4") || check_for_modules("ext4")); | ||
246 | if ((!test_fs || !ext4dev_present) && ext4_present) | ||
247 | return 0; | ||
248 | return 1; | ||
249 | } | ||
250 | |||
251 | niro | 532 | static int ext3_image(const void *buf, unsigned long long *bytes) |
252 | { | ||
253 | const struct ext3_super_block *sb = | ||
254 | (const struct ext3_super_block *)buf; | ||
255 | |||
256 | if (sb->s_magic == __cpu_to_le16(EXT2_SUPER_MAGIC) && | ||
257 | sb-> | ||
258 | s_feature_compat & __cpu_to_le32(EXT3_FEATURE_COMPAT_HAS_JOURNAL)) { | ||
259 | *bytes = (unsigned long long)__le32_to_cpu(sb->s_blocks_count) | ||
260 | << (10 + __le32_to_cpu(sb->s_log_block_size)); | ||
261 | return 1; | ||
262 | } | ||
263 | return 0; | ||
264 | } | ||
265 | |||
266 | static int ext2_image(const void *buf, unsigned long long *bytes) | ||
267 | { | ||
268 | const struct ext2_super_block *sb = | ||
269 | (const struct ext2_super_block *)buf; | ||
270 | |||
271 | if (sb->s_magic == __cpu_to_le16(EXT2_SUPER_MAGIC)) { | ||
272 | *bytes = (unsigned long long)__le32_to_cpu(sb->s_blocks_count) | ||
273 | << (10 + __le32_to_cpu(sb->s_log_block_size)); | ||
274 | return 1; | ||
275 | } | ||
276 | return 0; | ||
277 | } | ||
278 | |||
279 | static int reiserfs_image(const void *buf, unsigned long long *bytes) | ||
280 | { | ||
281 | const struct reiserfs_super_block *sb = | ||
282 | (const struct reiserfs_super_block *)buf; | ||
283 | |||
284 | if (memcmp(REISERFS_MAGIC(sb), REISERFS_SUPER_MAGIC_STRING, | ||
285 | sizeof(REISERFS_SUPER_MAGIC_STRING) - 1) == 0 || | ||
286 | memcmp(REISERFS_MAGIC(sb), REISER2FS_SUPER_MAGIC_STRING, | ||
287 | sizeof(REISER2FS_SUPER_MAGIC_STRING) - 1) == 0 || | ||
288 | memcmp(REISERFS_MAGIC(sb), REISER2FS_JR_SUPER_MAGIC_STRING, | ||
289 | sizeof(REISER2FS_JR_SUPER_MAGIC_STRING) - 1) == 0) { | ||
290 | *bytes = (unsigned long long)REISERFS_BLOCK_COUNT(sb) * | ||
291 | REISERFS_BLOCKSIZE(sb); | ||
292 | return 1; | ||
293 | } | ||
294 | return 0; | ||
295 | } | ||
296 | |||
297 | niro | 815 | static int reiser4_image(const void *buf, unsigned long long *bytes) |
298 | { | ||
299 | const struct reiser4_master_sb *sb = | ||
300 | (const struct reiser4_master_sb *)buf; | ||
301 | |||
302 | if (memcmp(sb->ms_magic, REISER4_SUPER_MAGIC_STRING, | ||
303 | sizeof(REISER4_SUPER_MAGIC_STRING) - 1) == 0) { | ||
304 | *bytes = (unsigned long long) __le32_to_cpu(sb->ms_format) * | ||
305 | __le32_to_cpu(sb->ms_blksize); | ||
306 | return 1; | ||
307 | } | ||
308 | return 0; | ||
309 | } | ||
310 | |||
311 | niro | 532 | static int xfs_image(const void *buf, unsigned long long *bytes) |
312 | { | ||
313 | const struct xfs_sb *sb = (const struct xfs_sb *)buf; | ||
314 | |||
315 | if (__be32_to_cpu(sb->sb_magicnum) == XFS_SB_MAGIC) { | ||
316 | *bytes = __be64_to_cpu(sb->sb_dblocks) * | ||
317 | __be32_to_cpu(sb->sb_blocksize); | ||
318 | return 1; | ||
319 | } | ||
320 | return 0; | ||
321 | } | ||
322 | |||
323 | static int jfs_image(const void *buf, unsigned long long *bytes) | ||
324 | { | ||
325 | const struct jfs_superblock *sb = (const struct jfs_superblock *)buf; | ||
326 | |||
327 | if (!memcmp(sb->s_magic, JFS_MAGIC, 4)) { | ||
328 | niro | 815 | *bytes = __le64_to_cpu(sb->s_size) << __le16_to_cpu(sb->s_l2pbsize); |
329 | niro | 532 | return 1; |
330 | } | ||
331 | return 0; | ||
332 | } | ||
333 | |||
334 | static int luks_image(const void *buf, unsigned long long *blocks) | ||
335 | { | ||
336 | const struct luks_partition_header *lph = | ||
337 | (const struct luks_partition_header *)buf; | ||
338 | |||
339 | if (!memcmp(lph->magic, LUKS_MAGIC, LUKS_MAGIC_L)) { | ||
340 | /* FSSIZE is dictated by the underlying fs, not by LUKS */ | ||
341 | *blocks = 0; | ||
342 | return 1; | ||
343 | } | ||
344 | return 0; | ||
345 | } | ||
346 | |||
347 | static int swap_image(const void *buf, unsigned long long *blocks) | ||
348 | { | ||
349 | const struct swap_super_block *ssb = | ||
350 | (const struct swap_super_block *)buf; | ||
351 | |||
352 | if (!memcmp(ssb->magic, SWAP_MAGIC_1, SWAP_MAGIC_L) || | ||
353 | !memcmp(ssb->magic, SWAP_MAGIC_2, SWAP_MAGIC_L)) { | ||
354 | *blocks = 0; | ||
355 | return 1; | ||
356 | } | ||
357 | return 0; | ||
358 | } | ||
359 | |||
360 | static int suspend_image(const void *buf, unsigned long long *blocks) | ||
361 | { | ||
362 | const struct swap_super_block *ssb = | ||
363 | (const struct swap_super_block *)buf; | ||
364 | |||
365 | if (!memcmp(ssb->magic, SUSP_MAGIC_1, SUSP_MAGIC_L) || | ||
366 | !memcmp(ssb->magic, SUSP_MAGIC_2, SUSP_MAGIC_L) || | ||
367 | !memcmp(ssb->magic, SUSP_MAGIC_U, SUSP_MAGIC_L)) { | ||
368 | *blocks = 0; | ||
369 | return 1; | ||
370 | } | ||
371 | return 0; | ||
372 | } | ||
373 | |||
374 | static int lvm2_image(const void *buf, unsigned long long *blocks) | ||
375 | { | ||
376 | const struct lvm2_super_block *lsb; | ||
377 | int i; | ||
378 | |||
379 | /* We must check every 512 byte sector */ | ||
380 | for (i = 0; i < BLOCK_SIZE; i += 0x200) { | ||
381 | lsb = (const struct lvm2_super_block *)(buf + i); | ||
382 | |||
383 | if (!memcmp(lsb->magic, LVM2_MAGIC, LVM2_MAGIC_L) && | ||
384 | !memcmp(lsb->type, LVM2_TYPE, LVM2_TYPE_L)) { | ||
385 | /* This is just one of possibly many PV's */ | ||
386 | *blocks = 0; | ||
387 | return 1; | ||
388 | } | ||
389 | } | ||
390 | |||
391 | return 0; | ||
392 | } | ||
393 | |||
394 | static int iso_image(const void *buf, unsigned long long *blocks) | ||
395 | { | ||
396 | const struct iso_volume_descriptor *isovd = | ||
397 | (const struct iso_volume_descriptor *)buf; | ||
398 | const struct iso_hs_volume_descriptor *isohsvd = | ||
399 | (const struct iso_hs_volume_descriptor *)buf; | ||
400 | |||
401 | if (!memcmp(isovd->id, ISO_MAGIC, ISO_MAGIC_L) || | ||
402 | !memcmp(isohsvd->id, ISO_HS_MAGIC, ISO_HS_MAGIC_L)) { | ||
403 | *blocks = 0; | ||
404 | return 1; | ||
405 | } | ||
406 | return 0; | ||
407 | } | ||
408 | |||
409 | niro | 815 | static int squashfs_image(const void *buf, unsigned long long *blocks) |
410 | { | ||
411 | const struct squashfs_super_block *sb = | ||
412 | (const struct squashfs_super_block *)buf; | ||
413 | |||
414 | if (sb->s_magic == SQUASHFS_MAGIC | ||
415 | || sb->s_magic == SQUASHFS_MAGIC_SWAP | ||
416 | || sb->s_magic == SQUASHFS_MAGIC_LZMA | ||
417 | || sb->s_magic == SQUASHFS_MAGIC_LZMA_SWAP) { | ||
418 | *blocks = (unsigned long long) sb->bytes_used; | ||
419 | return 1; | ||
420 | } | ||
421 | return 0; | ||
422 | } | ||
423 | |||
424 | static int gfs2_image(const void *buf, unsigned long long *bytes) | ||
425 | { | ||
426 | const struct gfs2_sb *sb = | ||
427 | (const struct gfs2_sb *)buf; | ||
428 | |||
429 | if (__be32_to_cpu(sb->sb_header.mh_magic) == GFS2_MAGIC | ||
430 | && (__be32_to_cpu(sb->sb_fs_format) == GFS2_FORMAT_FS | ||
431 | || __be32_to_cpu(sb->sb_fs_format) == GFS2_FORMAT_MULTI)) { | ||
432 | *bytes = 0; /* cpu_to_be32(sb->sb_bsize) * ?; */ | ||
433 | return 1; | ||
434 | } | ||
435 | return 0; | ||
436 | } | ||
437 | |||
438 | static int ocfs2_image(const void *buf, unsigned long long *bytes) | ||
439 | { | ||
440 | const struct ocfs2_dinode *sb = | ||
441 | (const struct ocfs2_dinode *)buf; | ||
442 | |||
443 | if (!memcmp(sb->i_signature, OCFS2_SUPER_BLOCK_SIGNATURE, | ||
444 | sizeof(OCFS2_SUPER_BLOCK_SIGNATURE) - 1)) { | ||
445 | *bytes = 0; | ||
446 | return 1; | ||
447 | } | ||
448 | return 0; | ||
449 | } | ||
450 | |||
451 | static int nilfs2_image(const void *buf, unsigned long long *bytes) | ||
452 | { | ||
453 | const struct nilfs_super_block *sb = | ||
454 | (const struct nilfs_super_block *)buf; | ||
455 | |||
456 | if (sb->s_magic == __cpu_to_le16(NILFS_SUPER_MAGIC) && | ||
457 | sb->s_rev_level == __cpu_to_le32(2)) { | ||
458 | *bytes = (unsigned long long)__le64_to_cpu(sb->s_dev_size); | ||
459 | return 1; | ||
460 | } | ||
461 | return 0; | ||
462 | } | ||
463 | |||
464 | niro | 532 | struct imagetype { |
465 | off_t block; | ||
466 | const char name[12]; | ||
467 | int (*identify) (const void *, unsigned long long *); | ||
468 | }; | ||
469 | |||
470 | /* | ||
471 | * Note: | ||
472 | * | ||
473 | * Minix test needs to come after ext3/ext2, since it's possible for | ||
474 | * ext3/ext2 to look like minix by pure random chance. | ||
475 | * | ||
476 | * LVM comes after all other filesystems since it's possible | ||
477 | * that an old lvm signature is left on the disk if pvremove | ||
478 | * is not used before creating the new fs. | ||
479 | * | ||
480 | * The same goes for LUKS as for LVM. | ||
481 | */ | ||
482 | static struct imagetype images[] = { | ||
483 | {0, "gzip", gzip_image}, | ||
484 | {0, "cramfs", cramfs_image}, | ||
485 | {0, "romfs", romfs_image}, | ||
486 | {0, "xfs", xfs_image}, | ||
487 | niro | 815 | {0, "squashfs", squashfs_image}, |
488 | {1, "ext4dev", ext4dev_image}, | ||
489 | {1, "ext4", ext4_image}, | ||
490 | niro | 532 | {1, "ext3", ext3_image}, |
491 | {1, "ext2", ext2_image}, | ||
492 | {1, "minix", minix_image}, | ||
493 | niro | 815 | {1, "nilfs2", nilfs2_image}, |
494 | {2, "ocfs2", ocfs2_image}, | ||
495 | niro | 532 | {8, "reiserfs", reiserfs_image}, |
496 | {64, "reiserfs", reiserfs_image}, | ||
497 | niro | 815 | {64, "reiser4", reiser4_image}, |
498 | {64, "gfs2", gfs2_image}, | ||
499 | niro | 532 | {32, "jfs", jfs_image}, |
500 | {32, "iso9660", iso_image}, | ||
501 | {0, "luks", luks_image}, | ||
502 | {0, "lvm2", lvm2_image}, | ||
503 | {1, "lvm2", lvm2_image}, | ||
504 | {-1, "swap", swap_image}, | ||
505 | {-1, "suspend", suspend_image}, | ||
506 | {0, "", NULL} | ||
507 | }; | ||
508 | |||
509 | int identify_fs(int fd, const char **fstype, | ||
510 | unsigned long long *bytes, off_t offset) | ||
511 | { | ||
512 | uint64_t buf[BLOCK_SIZE >> 3]; /* 64-bit worst case alignment */ | ||
513 | off_t cur_block = (off_t) - 1; | ||
514 | struct imagetype *ip; | ||
515 | int ret; | ||
516 | unsigned long long dummy; | ||
517 | |||
518 | if (!bytes) | ||
519 | bytes = &dummy; | ||
520 | |||
521 | *fstype = NULL; | ||
522 | *bytes = 0; | ||
523 | |||
524 | for (ip = images; ip->identify; ip++) { | ||
525 | /* Hack for swap, which apparently is dependent on page size */ | ||
526 | if (ip->block == -1) | ||
527 | ip->block = SWAP_OFFSET(); | ||
528 | |||
529 | if (cur_block != ip->block) { | ||
530 | /* | ||
531 | * Read block. | ||
532 | */ | ||
533 | cur_block = ip->block; | ||
534 | ret = pread(fd, buf, BLOCK_SIZE, | ||
535 | offset + cur_block * BLOCK_SIZE); | ||
536 | if (ret != BLOCK_SIZE) | ||
537 | return -1; /* error */ | ||
538 | } | ||
539 | |||
540 | if (ip->identify(buf, bytes)) { | ||
541 | *fstype = ip->name; | ||
542 | return 0; | ||
543 | } | ||
544 | } | ||
545 | |||
546 | return 1; /* Unknown filesystem */ | ||
547 | } |