Changeset 7efc517 in mainline for uspace/srv/fs/fat/fat_ops.c
- Timestamp:
- 2010-01-30T18:51:10Z (14 years ago)
- Branches:
- lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export
- Children:
- 64bc4b6, 89ee7ff
- Parents:
- 593585df
- File:
-
- 1 edited
Legend:
- Unmodified
- Added
- Removed
-
uspace/srv/fs/fat/fat_ops.c
r593585df r7efc517 290 290 291 291 *nodepp = nodep; 292 return EOK;293 }294 295 /** Perform basic sanity checks on the file system.296 *297 * Verify if values of boot sector fields are sane. Also verify media298 * descriptor. This is used to rule out cases when a device obviously299 * does not contain a fat file system.300 */301 static int fat_sanity_check(fat_bs_t *bs, dev_handle_t dev_handle)302 {303 fat_cluster_t e0, e1;304 unsigned fat_no;305 int rc;306 307 /* Check number of FATs. */308 if (bs->fatcnt == 0)309 return ENOTSUP;310 311 /* Check total number of sectors. */312 313 if (bs->totsec16 == 0 && bs->totsec32 == 0)314 return ENOTSUP;315 316 if (bs->totsec16 != 0 && bs->totsec32 != 0 &&317 bs->totsec16 != bs->totsec32)318 return ENOTSUP;319 320 /* Check media descriptor. Must be between 0xf0 and 0xff. */321 if ((bs->mdesc & 0xf0) != 0xf0)322 return ENOTSUP;323 324 /* Check number of sectors per FAT. */325 if (bs->sec_per_fat == 0)326 return ENOTSUP;327 328 /*329 * Check that the root directory entries take up whole blocks.330 * This check is rather strict, but it allows us to treat the root331 * directory and non-root directories uniformly in some places.332 * It can be removed provided that functions such as fat_read() are333 * sanitized to support file systems with this property.334 */335 if ((uint16_t_le2host(bs->root_ent_max) * sizeof(fat_dentry_t)) %336 uint16_t_le2host(bs->bps) != 0)337 return ENOTSUP;338 339 /* Check signature of each FAT. */340 341 for (fat_no = 0; fat_no < bs->fatcnt; fat_no++) {342 rc = fat_get_cluster(bs, dev_handle, fat_no, 0, &e0);343 if (rc != EOK)344 return EIO;345 346 rc = fat_get_cluster(bs, dev_handle, fat_no, 1, &e1);347 if (rc != EOK)348 return EIO;349 350 /* Check that first byte of FAT contains the media descriptor. */351 if ((e0 & 0xff) != bs->mdesc)352 return ENOTSUP;353 354 /*355 * Check that remaining bits of the first two entries are356 * set to one.357 */358 if ((e0 >> 8) != 0xff || e1 != 0xffff)359 return ENOTSUP;360 }361 362 292 return EOK; 363 293 }
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