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fs: fat: assure iterator's ->dent belongs to ->clust 

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>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
AKASHI Takahiro 2018-09-11 15:59:00 +09:00 committed by Alexander Graf
parent b94b6be543
commit f528c140c8
1 changed files with 17 additions and 8 deletions
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25
fs/fat/fat.c
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@ -641,6 +641,7 @@ static int get_fs_info(fsdata *mydata)
typedef struct { typedef struct {
fsdata *fsdata; /* filesystem parameters */ fsdata *fsdata; /* filesystem parameters */
unsigned clust; /* current cluster */ unsigned clust; /* current cluster */
unsigned next_clust; /* next cluster if remaining == 0 */
int last_cluster; /* set once we've read last cluster */ int last_cluster; /* set once we've read last cluster */
int is_root; /* is iterator at root directory */ int is_root; /* is iterator at root directory */
int remaining; /* remaining dent's in current cluster */ 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->fsdata = fsdata;
itr->clust = fsdata->root_cluster; itr->clust = fsdata->root_cluster;
itr->next_clust = fsdata->root_cluster;
itr->dent = NULL; itr->dent = NULL;
itr->remaining = 0; itr->remaining = 0;
itr->last_cluster = 0; itr->last_cluster = 0;
@ -707,9 +709,11 @@ static void fat_itr_child(fat_itr *itr, fat_itr *parent)
itr->fsdata = parent->fsdata; itr->fsdata = parent->fsdata;
if (clustnum > 0) { if (clustnum > 0) {
itr->clust = clustnum; itr->clust = clustnum;
itr->next_clust = clustnum;
itr->is_root = 0; itr->is_root = 0;
} else { } else {
itr->clust = parent->fsdata->root_cluster; itr->clust = parent->fsdata->root_cluster;
itr->next_clust = parent->fsdata->root_cluster;
itr->is_root = 1; itr->is_root = 1;
} }
itr->dent = NULL; itr->dent = NULL;
@ -727,7 +731,7 @@ static void *next_cluster(fat_itr *itr)
if (itr->last_cluster) if (itr->last_cluster)
return NULL; 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", debug("FAT read(sect=%d), clust_size=%d, DIRENTSPERBLOCK=%zd\n",
sect, itr->fsdata->clust_size, DIRENTSPERBLOCK); sect, itr->fsdata->clust_size, DIRENTSPERBLOCK);
@ -748,18 +752,19 @@ static void *next_cluster(fat_itr *itr)
return NULL; return NULL;
} }
itr->clust = itr->next_clust;
if (itr->is_root && itr->fsdata->fatsize != 32) { if (itr->is_root && itr->fsdata->fatsize != 32) {
itr->clust++; itr->next_clust++;
sect = clust_to_sect(itr->fsdata, itr->clust); sect = clust_to_sect(itr->fsdata, itr->next_clust);
if (sect - itr->fsdata->rootdir_sect >= if (sect - itr->fsdata->rootdir_sect >=
itr->fsdata->rootdir_size) { itr->fsdata->rootdir_size) {
debug("cursect: 0x%x\n", itr->clust); debug("nextclust: 0x%x\n", itr->next_clust);
itr->last_cluster = 1; itr->last_cluster = 1;
} }
} else { } else {
itr->clust = get_fatent(itr->fsdata, itr->clust); itr->next_clust = get_fatent(itr->fsdata, itr->next_clust);
if (CHECK_CLUST(itr->clust, itr->fsdata->fatsize)) { if (CHECK_CLUST(itr->next_clust, itr->fsdata->fatsize)) {
debug("cursect: 0x%x\n", itr->clust); debug("nextclust: 0x%x\n", itr->next_clust);
itr->last_cluster = 1; itr->last_cluster = 1;
} }
} }
@ -775,8 +780,11 @@ static dir_entry *next_dent(fat_itr *itr)
itr->fsdata->clust_size; itr->fsdata->clust_size;
/* have we reached the last cluster? */ /* have we reached the last cluster? */
if (!dent) if (!dent) {
/* a sign for no more entries left */
itr->dent = NULL;
return NULL; return NULL;
}
itr->remaining = nbytes / sizeof(dir_entry) - 1; itr->remaining = nbytes / sizeof(dir_entry) - 1;
itr->dent = dent; 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))) { (((next - path) == 2) && !strncmp(path, "..", 2))) {
/* point back to itself */ /* point back to itself */
itr->clust = itr->fsdata->root_cluster; itr->clust = itr->fsdata->root_cluster;
itr->next_clust = itr->fsdata->root_cluster;
itr->dent = NULL; itr->dent = NULL;
itr->remaining = 0; itr->remaining = 0;
itr->last_cluster = 0; itr->last_cluster = 0;