When storage devices contain files larger than the embedded RAM, it is useful to
be able to read these files by chunks, e.g. for a software update to the
embedded NAND Flash from an external storage device (USB stick, SD card, etc.).
Hence, this patch makes it possible by adding a new FAT API to read files from a
given position.
Signed-off-by: Benoît Thébaudeau <benoit.thebaud...@advansee.com>
Cc: Wolfgang Denk <w...@denx.de>
---
.../fs/fat/fat.c | 90 ++++++++++++++++----
1 file changed, 72 insertions(+), 18 deletions(-)
diff --git u-boot-66714b1.orig/fs/fat/fat.c u-boot-66714b1/fs/fat/fat.c
index 8ac8b85..709a5eb 100644
--- u-boot-66714b1.orig/fs/fat/fat.c
+++ u-boot-66714b1/fs/fat/fat.c
@@ -329,13 +329,16 @@ get_cluster (fsdata *mydata, __u32 clustnum, __u8 *buffer,
}
/*
- * Read at most 'maxsize' bytes from the file associated with 'dentptr'
+ * Read at most 'maxsize' bytes from 'pos' in the file associated with
'dentptr'
* into 'buffer'.
* Return the number of bytes read or -1 on fatal errors.
*/
+__u8 get_contents_vfatname_block[MAX_CLUSTSIZE]
+ __aligned(ARCH_DMA_MINALIGN);
+
static long
-get_contents (fsdata *mydata, dir_entry *dentptr, __u8 *buffer,
- unsigned long maxsize)
+get_contents (fsdata *mydata, dir_entry *dentptr, unsigned long pos,
+ __u8 *buffer, unsigned long maxsize)
{
unsigned long filesize = FAT2CPU32(dentptr->size), gotsize = 0;
unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
@@ -345,12 +348,59 @@ get_contents (fsdata *mydata, dir_entry *dentptr, __u8
*buffer,
debug("Filesize: %ld bytes\n", filesize);
- if (maxsize > 0 && filesize > maxsize)
- filesize = maxsize;
+ if (pos >= filesize) {
+ debug("Read position past EOF: %lu\n", pos);
+ return gotsize;
+ }
+
+ if (maxsize > 0 && filesize > pos + maxsize)
+ filesize = pos + maxsize;
debug("%ld bytes\n", filesize);
actsize = bytesperclust;
+
+ /* go to cluster at pos */
+ while (actsize <= pos) {
+ curclust = get_fatent(mydata, curclust);
+ if (CHECK_CLUST(curclust, mydata->fatsize)) {
+ debug("curclust: 0x%x\n", curclust);
+ debug("Invalid FAT entry\n");
+ return gotsize;
+ }
+ actsize += bytesperclust;
+ }
+
+ /* actsize > pos */
+ actsize -= bytesperclust;
+ filesize -= actsize;
+ pos -= actsize;
+
+ /* align to beginning of next cluster if any */
+ if (pos) {
+ actsize = min(filesize, bytesperclust);
+ if (get_cluster(mydata, curclust, get_contents_vfatname_block,
+ (int)actsize) != 0) {
+ printf("Error reading cluster\n");
+ return -1;
+ }
+ filesize -= actsize;
+ actsize -= pos;
+ memcpy(buffer, get_contents_vfatname_block + pos, actsize);
+ gotsize += actsize;
+ if (!filesize)
+ return gotsize;
+ buffer += actsize;
+
+ curclust = get_fatent(mydata, curclust);
+ if (CHECK_CLUST(curclust, mydata->fatsize)) {
+ debug("curclust: 0x%x\n", curclust);
+ debug("Invalid FAT entry\n");
+ return gotsize;
+ }
+ }
+
+ actsize = bytesperclust;
endclust = curclust;
do {
@@ -434,9 +484,6 @@ static int slot2str (dir_slot *slotptr, char *l_name, int
*idx)
* into 'retdent'
* Return 0 on success, -1 otherwise.
*/
-__u8 get_vfatname_block[MAX_CLUSTSIZE]
- __aligned(ARCH_DMA_MINALIGN);
-
static int
get_vfatname (fsdata *mydata, int curclust, __u8 *cluster,
dir_entry *retdent, char *l_name)
@@ -475,13 +522,13 @@ get_vfatname (fsdata *mydata, int curclust, __u8 *cluster,
return -1;
}
- if (get_cluster(mydata, curclust, get_vfatname_block,
+ if (get_cluster(mydata, curclust, get_contents_vfatname_block,
mydata->clust_size * mydata->sect_size) != 0) {
debug("Error: reading directory block\n");
return -1;
}
- slotptr2 = (dir_slot *)get_vfatname_block;
+ slotptr2 = (dir_slot *)get_contents_vfatname_block;
while (counter > 0) {
if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
& 0xff) != counter)
@@ -492,7 +539,7 @@ get_vfatname (fsdata *mydata, int curclust, __u8 *cluster,
/* Save the real directory entry */
realdent = (dir_entry *)slotptr2;
- while ((__u8 *)slotptr2 > get_vfatname_block) {
+ while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
slotptr2--;
slot2str(slotptr2, l_name, &idx);
}
@@ -771,12 +818,12 @@ exit:
return ret;
}
-__u8 do_fat_read_block[MAX_CLUSTSIZE]
+__u8 do_fat_read_at_block[MAX_CLUSTSIZE]
__aligned(ARCH_DMA_MINALIGN);
long
-do_fat_read (const char *filename, void *buffer, unsigned long maxsize,
- int dols)
+do_fat_read_at (const char *filename, unsigned long pos, void *buffer,
+ unsigned long maxsize, int dols)
{
char fnamecopy[2048];
boot_sector bs;
@@ -890,12 +937,12 @@ do_fat_read (const char *filename, void *buffer, unsigned
long maxsize,
(mydata->fatsize == 32) ?
(mydata->clust_size) :
PREFETCH_BLOCKS,
- do_fat_read_block) < 0) {
+ do_fat_read_at_block) < 0) {
debug("Error: reading rootdir block\n");
goto exit;
}
- dentptr = (dir_entry *) do_fat_read_block;
+ dentptr = (dir_entry *) do_fat_read_at_block;
}
for (i = 0; i < DIRENTSPERBLOCK; i++) {
@@ -915,7 +962,7 @@ do_fat_read (const char *filename, void *buffer, unsigned
long maxsize,
get_vfatname(mydata,
root_cluster,
- do_fat_read_block,
+ do_fat_read_at_block,
dentptr, l_name);
if (dols == LS_ROOT) {
@@ -1118,7 +1165,7 @@ rootdir_done:
subname = nextname;
}
- ret = get_contents(mydata, dentptr, buffer, maxsize);
+ ret = get_contents(mydata, dentptr, pos, buffer, maxsize);
debug("Size: %d, got: %ld\n", FAT2CPU32(dentptr->size), ret);
exit:
@@ -1126,6 +1173,13 @@ exit:
return ret;
}
+long
+do_fat_read (const char *filename, void *buffer, unsigned long maxsize,
+ int dols)
+{
+ return do_fat_read_at(filename, 0, buffer, maxsize, dols);
+}
+
int file_fat_detectfs (void)
{
boot_sector bs;
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