Changeset 7efc517 in mainline
- Timestamp:
- 2010-01-30T18:51:10Z (15 years ago)
- Branches:
- lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export
- Children:
- 64bc4b6, 89ee7ff
- Parents:
- 593585df
- Location:
- uspace/srv/fs/fat
- Files:
-
- 3 edited
Legend:
- Unmodified
- Added
- Removed
-
uspace/srv/fs/fat/fat_fat.c
r593585df r7efc517 608 608 } 609 609 610 /** Perform basic sanity checks on the file system. 611 * 612 * Verify if values of boot sector fields are sane. Also verify media 613 * descriptor. This is used to rule out cases when a device obviously 614 * does not contain a fat file system. 615 */ 616 int fat_sanity_check(fat_bs_t *bs, dev_handle_t dev_handle) 617 { 618 fat_cluster_t e0, e1; 619 unsigned fat_no; 620 int rc; 621 622 /* Check number of FATs. */ 623 if (bs->fatcnt == 0) 624 return ENOTSUP; 625 626 /* Check total number of sectors. */ 627 628 if (bs->totsec16 == 0 && bs->totsec32 == 0) 629 return ENOTSUP; 630 631 if (bs->totsec16 != 0 && bs->totsec32 != 0 && 632 bs->totsec16 != bs->totsec32) 633 return ENOTSUP; 634 635 /* Check media descriptor. Must be between 0xf0 and 0xff. */ 636 if ((bs->mdesc & 0xf0) != 0xf0) 637 return ENOTSUP; 638 639 /* Check number of sectors per FAT. */ 640 if (bs->sec_per_fat == 0) 641 return ENOTSUP; 642 643 /* 644 * Check that the root directory entries take up whole blocks. 645 * This check is rather strict, but it allows us to treat the root 646 * directory and non-root directories uniformly in some places. 647 * It can be removed provided that functions such as fat_read() are 648 * sanitized to support file systems with this property. 649 */ 650 if ((uint16_t_le2host(bs->root_ent_max) * sizeof(fat_dentry_t)) % 651 uint16_t_le2host(bs->bps) != 0) 652 return ENOTSUP; 653 654 /* Check signature of each FAT. */ 655 656 for (fat_no = 0; fat_no < bs->fatcnt; fat_no++) { 657 rc = fat_get_cluster(bs, dev_handle, fat_no, 0, &e0); 658 if (rc != EOK) 659 return EIO; 660 661 rc = fat_get_cluster(bs, dev_handle, fat_no, 1, &e1); 662 if (rc != EOK) 663 return EIO; 664 665 /* Check that first byte of FAT contains the media descriptor. */ 666 if ((e0 & 0xff) != bs->mdesc) 667 return ENOTSUP; 668 669 /* 670 * Check that remaining bits of the first two entries are 671 * set to one. 672 */ 673 if ((e0 >> 8) != 0xff || e1 != 0xffff) 674 return ENOTSUP; 675 } 676 677 return EOK; 678 } 679 610 680 /** 611 681 * @} -
uspace/srv/fs/fat/fat_fat.h
r593585df r7efc517 87 87 off_t); 88 88 extern int fat_zero_cluster(struct fat_bs *, dev_handle_t, fat_cluster_t); 89 extern int fat_sanity_check(struct fat_bs *, dev_handle_t); 89 90 90 91 #endif -
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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