781b672b3
Denis Vlasenko
2009-03-28
Subject
mkfs.vfat: fix a problem with over-estimating FAT size
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util-linux/mkfs_vfat.c+15 -6
| @@ -327,6 +327,7 @@ int mkfs_vfat_main(int argc UNUSED_PARAM, char **argv) | |
| volume_size_bytes >= ((off_t)8)*1024*1024*1024 ? 16 : | |
| volume_size_bytes >= 260*1024*1024 ? 8 : 1; | |
| } else { | |
| + | // floppy, loop, or regular file |
| int not_floppy = ioctl(dev, FDGETPRM, ¶m); | |
| if (not_floppy == 0) { | |
| // floppy disk | |
| @@ -367,12 +368,14 @@ int mkfs_vfat_main(int argc UNUSED_PARAM, char **argv) | |
| // Calculate number of clusters, sectors/cluster, sectors/FAT | |
| // (an initial guess for sect_per_clust should already be set) | |
| // | |
| - | if ((off_t)(volume_size_sect - reserved_sect) < 16) // arbitrary limit |
| + | // "mkdosfs -v -F 32 image5k 5" is the minimum: |
| + | // 2 sectors for FATs and 2 data sectors |
| + | if ((off_t)(volume_size_sect - reserved_sect) < 4) |
| bb_error_msg_and_die("the image is too small for FAT32"); | |
| sect_per_fat = 1; | |
| while (1) { | |
| while (1) { | |
| - | unsigned spf; |
| + | int spf_adj; |
| off_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, | |
| @@ -382,8 +385,13 @@ int mkfs_vfat_main(int argc UNUSED_PARAM, char **argv) | |
| if (tcl > 0x7fffffff) | |
| goto next; | |
| total_clust = tcl; // fits in uint32_t | |
| - | spf = ((total_clust + 2) * 4 + bytes_per_sect - 1) / bytes_per_sect; |
| - | if (spf <= sect_per_fat) { |
| + | spf_adj = ((total_clust + 2) * 4 + bytes_per_sect - 1) / bytes_per_sect - 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); |
| + | bb_error_msg("adjust to sect_per_fat:%d", spf_adj); |
| + | #endif |
| + | if (spf_adj <= 0) { |
| // do not need to adjust sect_per_fat. | |
| // so, was total_clust too big after all? | |
| if (total_clust <= MAX_CLUST_32) | |
| @@ -392,7 +400,8 @@ int mkfs_vfat_main(int argc UNUSED_PARAM, char **argv) | |
| goto next; | |
| } | |
| // adjust sect_per_fat, go back and recalc total_clust | |
| - | sect_per_fat = spf; |
| + | // (note: just "sect_per_fat += spf_adj" isn't ok) |
| + | sect_per_fat += ((unsigned)spf_adj / 2) | 1; |
| } | |
| next: | |
| if (sect_per_clust == 128) | |
| @@ -409,7 +418,7 @@ int mkfs_vfat_main(int argc UNUSED_PARAM, char **argv) | |
| fprintf(stderr, | |
| "Device '%s':\n" | |
| "heads:%u, sectors/track:%u, bytes/sector:%u\n" | |
| - | "media descriptor:0x%02x\n" |
| + | "media descriptor:%02x\n" |
| "total sectors:%"OFF_FMT"u, clusters:%u, sectors/cluster:%u\n" | |
| "FATs:2, sectors/FAT:%u\n" | |
| "volumeID:%08x, label:'%s'\n", | |