diff options
Diffstat (limited to 'util-linux/mkfs_vfat.c')
| -rw-r--r-- | util-linux/mkfs_vfat.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/util-linux/mkfs_vfat.c b/util-linux/mkfs_vfat.c index 10de2af5b..de88a7443 100644 --- a/util-linux/mkfs_vfat.c +++ b/util-linux/mkfs_vfat.c | |||
| @@ -391,16 +391,22 @@ int mkfs_vfat_main(int argc UNUSED_PARAM, char **argv) | |||
| 391 | while (1) { | 391 | while (1) { |
| 392 | while (1) { | 392 | while (1) { |
| 393 | int spf_adj; | 393 | int spf_adj; |
| 394 | off_t tcl = (volume_size_sect - reserved_sect - NUM_FATS * sect_per_fat) / sect_per_clust; | 394 | uoff_t tcl = (volume_size_sect - reserved_sect - NUM_FATS * sect_per_fat) / sect_per_clust; |
| 395 | // tcl may be > MAX_CLUST_32 here, but it may be | 395 | // tcl may be > MAX_CLUST_32 here, but it may be |
| 396 | // because sect_per_fat is underestimated, | 396 | // because sect_per_fat is underestimated, |
| 397 | // and with increased sect_per_fat it still may become | 397 | // and with increased sect_per_fat it still may become |
| 398 | // <= MAX_CLUST_32. Therefore, we do not check | 398 | // <= MAX_CLUST_32. Therefore, we do not check |
| 399 | // against MAX_CLUST_32, but against a bigger const: | 399 | // against MAX_CLUST_32, but against a bigger const: |
| 400 | if (tcl > 0x7fffffff) | 400 | if (tcl > 0x80ffffff) |
| 401 | goto next; | 401 | goto next; |
| 402 | total_clust = tcl; // fits in uint32_t | 402 | total_clust = tcl; // fits in uint32_t |
| 403 | spf_adj = ((total_clust + 2) * 4 + bytes_per_sect - 1) / bytes_per_sect - sect_per_fat; | 403 | // Every cluster needs 4 bytes in FAT. +2 entries since |
| 404 | // FAT has space for non-existent clusters 0 and 1. | ||
| 405 | // Let's see how many sectors that needs. | ||
| 406 | //May overflow at "*4": | ||
| 407 | //spf_adj = ((total_clust+2) * 4 + bytes_per_sect-1) / bytes_per_sect - sect_per_fat; | ||
| 408 | //Same in the more obscure, non-overflowing form: | ||
| 409 | spf_adj = ((total_clust+2) + (bytes_per_sect/4)-1) / (bytes_per_sect/4) - sect_per_fat; | ||
| 404 | #if 0 | 410 | #if 0 |
| 405 | bb_error_msg("sect_per_clust:%u sect_per_fat:%u total_clust:%u", | 411 | bb_error_msg("sect_per_clust:%u sect_per_fat:%u total_clust:%u", |
| 406 | sect_per_clust, sect_per_fat, (int)tcl); | 412 | sect_per_clust, sect_per_fat, (int)tcl); |