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mkfs_vfat: fixes for large image cases

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2009-11-03 14:12:04 +01:00
parent 68c67469aa
commit 692bcff577
1 changed files with 9 additions and 3 deletions
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12
util-linux/mkfs_vfat.c
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@ -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);