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authorWu, Josh <Josh.wu@atmel.com>2014-05-08 16:14:07 +0800
committerTom Rini <trini@ti.com>2014-05-12 16:31:51 -0400
commitdd6d7967dfa88bd51062a8afb004962d16006ecd (patch)
treeecfe8eb5205642f8eb65d6d623575f5769f1469a
parent2e98f70882f8c1a09b662137884c1435a97c9a1c (diff)
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fs/fat: correct FAT16/12 file finding in root dir
When write a file into FAT file system, it will search a match file in root dir. So the find_directory_entry() will get the first cluster of root dir content and search the directory item one by one. If the file is not found, we will call get_fatent_value() to get next cluster of root dir via lookup the FAT table and continue the search. The issue is in FAT16/12 system, we cannot get root dir's next clust from FAT table. The FAT table only be use to find the clust of data aera in FAT16/12. In FAT16/12 if the clust is in root dir, the clust number is a negative number or 0, 1. Since root dir is located in front of the data area. Data area start clust #2. So the root dir clust number should < 2. This patch will check above situation before call get_fatenv_value(). If curclust is < 2, include minus number, we just increase one on the curclust since root dir is in continous cluster. The patch also add a sanity check for entry in get_fatenv_value(). Signed-off-by: Josh Wu <josh.wu@atmel.com>
-rw-r--r--fs/fat/fat_write.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 90d6ab6..ba7e3ae 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -139,6 +139,11 @@ static __u32 get_fatent_value(fsdata *mydata, __u32 entry)
__u32 ret = 0x00;
__u16 val1, val2;
+ if (CHECK_CLUST(entry, mydata->fatsize)) {
+ printf("Error: Invalid FAT entry: 0x%08x\n", entry);
+ return ret;
+ }
+
switch (mydata->fatsize) {
case 32:
bufnum = entry / FAT32BUFSIZE;
@@ -881,6 +886,28 @@ static dir_entry *find_directory_entry(fsdata *mydata, int startsect,
return dentptr;
}
+ /*
+ * In FAT16/12, the root dir is locate before data area, shows
+ * in following:
+ * -------------------------------------------------------------
+ * | Boot | FAT1 & 2 | Root dir | Data (start from cluster #2) |
+ * -------------------------------------------------------------
+ *
+ * As a result if curclust is in Root dir, it is a negative
+ * number or 0, 1.
+ *
+ */
+ if (mydata->fatsize != 32 && (int)curclust <= 1) {
+ /* Current clust is in root dir, set to next clust */
+ curclust++;
+ if ((int)curclust <= 1)
+ continue; /* continue to find */
+
+ /* Reach the end of root dir */
+ empty_dentptr = dentptr;
+ return NULL;
+ }
+
curclust = get_fatent_value(mydata, dir_curclust);
if (IS_LAST_CLUST(curclust, mydata->fatsize)) {
empty_dentptr = dentptr;