From: AKASHI Takahiro takahiro.akashi@linaro.org
In my attempt to re-work write operation, it was revealed that iterator's "clust" does not always point to a cluster to which a current directory entry ("dent") belongs. This patch assures that it is always true by adding "next_clust" which is used solely for dereferencing a cluster chain.
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- fs/fat/fat.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)
diff --git a/fs/fat/fat.c b/fs/fat/fat.c index eaea9300fd7f..afb8b3f9ef1a 100644 --- a/fs/fat/fat.c +++ b/fs/fat/fat.c @@ -641,6 +641,7 @@ static int get_fs_info(fsdata *mydata) typedef struct { fsdata *fsdata; /* filesystem parameters */ unsigned clust; /* current cluster */ + unsigned next_clust; /* next cluster if remaining == 0 */ int last_cluster; /* set once we've read last cluster */ int is_root; /* is iterator at root directory */ int remaining; /* remaining dent's in current cluster */ @@ -672,6 +673,7 @@ static int fat_itr_root(fat_itr *itr, fsdata *fsdata)
itr->fsdata = fsdata; itr->clust = fsdata->root_cluster; + itr->next_clust = fsdata->root_cluster; itr->dent = NULL; itr->remaining = 0; itr->last_cluster = 0; @@ -707,9 +709,11 @@ static void fat_itr_child(fat_itr *itr, fat_itr *parent) itr->fsdata = parent->fsdata; if (clustnum > 0) { itr->clust = clustnum; + itr->next_clust = clustnum; itr->is_root = 0; } else { itr->clust = parent->fsdata->root_cluster; + itr->next_clust = parent->fsdata->root_cluster; itr->is_root = 1; } itr->dent = NULL; @@ -727,7 +731,7 @@ static void *next_cluster(fat_itr *itr) if (itr->last_cluster) return NULL;
- sect = clust_to_sect(itr->fsdata, itr->clust); + sect = clust_to_sect(itr->fsdata, itr->next_clust);
debug("FAT read(sect=%d), clust_size=%d, DIRENTSPERBLOCK=%zd\n", sect, itr->fsdata->clust_size, DIRENTSPERBLOCK); @@ -748,18 +752,19 @@ static void *next_cluster(fat_itr *itr) return NULL; }
+ itr->clust = itr->next_clust; if (itr->is_root && itr->fsdata->fatsize != 32) { - itr->clust++; - sect = clust_to_sect(itr->fsdata, itr->clust); + itr->next_clust++; + sect = clust_to_sect(itr->fsdata, itr->next_clust); if (sect - itr->fsdata->rootdir_sect >= itr->fsdata->rootdir_size) { - debug("cursect: 0x%x\n", itr->clust); + debug("nextclust: 0x%x\n", itr->next_clust); itr->last_cluster = 1; } } else { - itr->clust = get_fatent(itr->fsdata, itr->clust); - if (CHECK_CLUST(itr->clust, itr->fsdata->fatsize)) { - debug("cursect: 0x%x\n", itr->clust); + itr->next_clust = get_fatent(itr->fsdata, itr->next_clust); + if (CHECK_CLUST(itr->next_clust, itr->fsdata->fatsize)) { + debug("nextclust: 0x%x\n", itr->next_clust); itr->last_cluster = 1; } } @@ -775,8 +780,11 @@ static dir_entry *next_dent(fat_itr *itr) itr->fsdata->clust_size;
/* have we reached the last cluster? */ - if (!dent) + if (!dent) { + /* a sign for no more entries left */ + itr->dent = NULL; return NULL; + }
itr->remaining = nbytes / sizeof(dir_entry) - 1; itr->dent = dent; @@ -937,6 +945,7 @@ static int fat_itr_resolve(fat_itr *itr, const char *path, unsigned type) (((next - path) == 2) && !strncmp(path, "..", 2))) { /* point back to itself */ itr->clust = itr->fsdata->root_cluster; + itr->next_clust = itr->fsdata->root_cluster; itr->dent = NULL; itr->remaining = 0; itr->last_cluster = 0;