692bcff57
Denys Vlasenko
2009-11-03
Subject
mkfs_vfat: fixes for large image cases
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util-linux/mkfs_vfat.c+9 -3
| @@ -391,16 +391,22 @@ int mkfs_vfat_main(int argc UNUSED_PARAM, char **argv) | |
| while (1) { | |
| while (1) { | |
| int spf_adj; | |
| - | off_t tcl = (volume_size_sect - reserved_sect - NUM_FATS * sect_per_fat) / sect_per_clust; |
| + | uoff_t tcl = (volume_size_sect - reserved_sect - NUM_FATS * sect_per_fat) / sect_per_clust; |
| // tcl may be > MAX_CLUST_32 here, but it may be | |
| // because sect_per_fat is underestimated, | |
| // and with increased sect_per_fat it still may become | |
| // <= MAX_CLUST_32. Therefore, we do not check | |
| // against MAX_CLUST_32, but against a bigger const: | |
| - | if (tcl > 0x7fffffff) |
| + | if (tcl > 0x80ffffff) |
| goto next; | |
| total_clust = tcl; // fits in uint32_t | |
| - | spf_adj = ((total_clust + 2) * 4 + bytes_per_sect - 1) / bytes_per_sect - sect_per_fat; |
| + | // Every cluster needs 4 bytes in FAT. +2 entries since |
| + | // FAT has space for non-existent clusters 0 and 1. |
| + | // Let's see how many sectors that needs. |
| + | //May overflow at "*4": |
| + | //spf_adj = ((total_clust+2) * 4 + bytes_per_sect-1) / bytes_per_sect - sect_per_fat; |
| + | //Same in the more obscure, non-overflowing form: |
| + | spf_adj = ((total_clust+2) + (bytes_per_sect/4)-1) / (bytes_per_sect/4) - sect_per_fat; |
| #if 0 | |
| bb_error_msg("sect_per_clust:%u sect_per_fat:%u total_clust:%u", | |
| sect_per_clust, sect_per_fat, (int)tcl); | |