diff options
| -rw-r--r-- | fs/fat/fat.c | 47 |
1 files changed, 34 insertions, 13 deletions
diff --git a/fs/fat/fat.c b/fs/fat/fat.c index 6ade4ea54ec..c5997c21735 100644 --- a/fs/fat/fat.c +++ b/fs/fat/fat.c @@ -602,8 +602,13 @@ static int get_fs_info(fsdata *mydata) mydata->data_begin = mydata->rootdir_sect + mydata->rootdir_size - (mydata->clust_size * 2); - mydata->root_cluster = - sect_to_clust(mydata, mydata->rootdir_sect); + + /* + * The root directory is not cluster-aligned and may be on a + * "negative" cluster, this will be handled specially in + * next_cluster(). + */ + mydata->root_cluster = 0; } mydata->fatbufnum = -1; @@ -733,20 +738,38 @@ static void fat_itr_child(fat_itr *itr, fat_itr *parent) itr->last_cluster = 0; } -static void *next_cluster(fat_itr *itr) +static void *next_cluster(fat_itr *itr, unsigned *nbytes) { fsdata *mydata = itr->fsdata; /* for silly macros */ int ret; u32 sect; + u32 read_size; /* have we reached the end? */ if (itr->last_cluster) return NULL; - sect = clust_to_sect(itr->fsdata, itr->next_clust); + if (itr->is_root && itr->fsdata->fatsize != 32) { + /* + * The root directory is located before the data area and + * cannot be indexed using the regular unsigned cluster + * numbers (it may start at a "negative" cluster or not at a + * cluster boundary at all), so consider itr->next_clust to be + * a offset in cluster-sized units from the start of rootdir. + */ + unsigned sect_offset = itr->next_clust * itr->fsdata->clust_size; + unsigned remaining_sects = itr->fsdata->rootdir_size - sect_offset; + sect = itr->fsdata->rootdir_sect + sect_offset; + /* do not read past the end of rootdir */ + read_size = min_t(u32, itr->fsdata->clust_size, + remaining_sects); + } else { + sect = clust_to_sect(itr->fsdata, itr->next_clust); + read_size = itr->fsdata->clust_size; + } - debug("FAT read(sect=%d), clust_size=%d, DIRENTSPERBLOCK=%zd\n", - sect, itr->fsdata->clust_size, DIRENTSPERBLOCK); + debug("FAT read(sect=%d), clust_size=%d, read_size=%u, DIRENTSPERBLOCK=%zd\n", + sect, itr->fsdata->clust_size, read_size, DIRENTSPERBLOCK); /* * NOTE: do_fat_read_at() had complicated logic to deal w/ @@ -757,18 +780,17 @@ static void *next_cluster(fat_itr *itr) * dent at a time and iteratively constructing the vfat long * name. */ - ret = disk_read(sect, itr->fsdata->clust_size, - itr->block); + ret = disk_read(sect, read_size, itr->block); if (ret < 0) { debug("Error: reading block\n"); return NULL; } + *nbytes = read_size * itr->fsdata->sect_size; itr->clust = itr->next_clust; if (itr->is_root && itr->fsdata->fatsize != 32) { itr->next_clust++; - sect = clust_to_sect(itr->fsdata, itr->next_clust); - if (sect - itr->fsdata->rootdir_sect >= + if (itr->next_clust * itr->fsdata->clust_size >= itr->fsdata->rootdir_size) { debug("nextclust: 0x%x\n", itr->next_clust); itr->last_cluster = 1; @@ -787,9 +809,8 @@ static void *next_cluster(fat_itr *itr) static dir_entry *next_dent(fat_itr *itr) { if (itr->remaining == 0) { - struct dir_entry *dent = next_cluster(itr); - unsigned nbytes = itr->fsdata->sect_size * - itr->fsdata->clust_size; + unsigned nbytes; + struct dir_entry *dent = next_cluster(itr, &nbytes); /* have we reached the last cluster? */ if (!dent) { |