fat: fatwrite: fix the command for FAT12
The u-boot command fatwrite empties FAT clusters from the beginning
till the end of the file.
Specifically for FAT12 it fails to detect the end of the file and goes
beyond the file bounds thus corrupting the file system.
Additionally, FAT entry chaining-up into a file is not implemented
for FAT12.
The users normally workaround this by re-formatting the partition as
FAT16/FAT32, like here:
https://github.com/FEDEVEL/openrex-uboot-v2015.10/issues/1
The patch fixes the bounds of a file and FAT12 entries chaining into
a file, including EOF markup.
Signed-off-by: Philipp Skadorov <philipp.skadorov@savoirfairelinux.com>
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 40a3860..aab0b0e 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -467,11 +467,12 @@
}
/*
- * Set the entry at index 'entry' in a FAT (16/32) table.
+ * Set the entry at index 'entry' in a FAT (12/16/32) table.
*/
static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
{
- __u32 bufnum, offset;
+ __u32 bufnum, offset, off16;
+ __u16 val1, val2;
switch (mydata->fatsize) {
case 32:
@@ -482,6 +483,10 @@
bufnum = entry / FAT16BUFSIZE;
offset = entry - bufnum * FAT16BUFSIZE;
break;
+ case 12:
+ bufnum = entry / FAT12BUFSIZE;
+ offset = entry - bufnum * FAT12BUFSIZE;
+ break;
default:
/* Unsupported FAT size */
return -1;
@@ -521,6 +526,45 @@
case 16:
((__u16 *) mydata->fatbuf)[offset] = cpu_to_le16(entry_value);
break;
+ case 12:
+ off16 = (offset * 3) / 4;
+
+ switch (offset & 0x3) {
+ case 0:
+ val1 = cpu_to_le16(entry_value) & 0xfff;
+ ((__u16 *)mydata->fatbuf)[off16] &= ~0xfff;
+ ((__u16 *)mydata->fatbuf)[off16] |= val1;
+ break;
+ case 1:
+ val1 = cpu_to_le16(entry_value) & 0xf;
+ val2 = (cpu_to_le16(entry_value) >> 4) & 0xff;
+
+ ((__u16 *)mydata->fatbuf)[off16] &= ~0xf000;
+ ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 12);
+
+ ((__u16 *)mydata->fatbuf)[off16 + 1] &= ~0xff;
+ ((__u16 *)mydata->fatbuf)[off16 + 1] |= val2;
+ break;
+ case 2:
+ val1 = cpu_to_le16(entry_value) & 0xff;
+ val2 = (cpu_to_le16(entry_value) >> 8) & 0xf;
+
+ ((__u16 *)mydata->fatbuf)[off16] &= ~0xff00;
+ ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 8);
+
+ ((__u16 *)mydata->fatbuf)[off16 + 1] &= ~0xf;
+ ((__u16 *)mydata->fatbuf)[off16 + 1] |= val2;
+ break;
+ case 3:
+ val1 = cpu_to_le16(entry_value) & 0xfff;
+ ((__u16 *)mydata->fatbuf)[off16] &= ~0xfff0;
+ ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 4);
+ break;
+ default:
+ break;
+ }
+
+ break;
default:
return -1;
}
@@ -529,7 +573,7 @@
}
/*
- * Determine the next free cluster after 'entry' in a FAT (16/32) table
+ * Determine the next free cluster after 'entry' in a FAT (12/16/32) table
* and link it to 'entry'. EOC marker is not set on returned entry.
*/
static __u32 determine_fatent(fsdata *mydata, __u32 entry)
@@ -651,6 +695,8 @@
set_fatent_value(mydata, dir_newclust, 0xffffff8);
else if (mydata->fatsize == 16)
set_fatent_value(mydata, dir_newclust, 0xfff8);
+ else if (mydata->fatsize == 12)
+ set_fatent_value(mydata, dir_newclust, 0xff8);
dir_curclust = dir_newclust;
@@ -670,16 +716,13 @@
{
__u32 fat_val;
- while (1) {
+ while (!CHECK_CLUST(entry, mydata->fatsize)) {
fat_val = get_fatent_value(mydata, entry);
if (fat_val != 0)
set_fatent_value(mydata, entry, 0);
else
break;
- if (fat_val == 0xfffffff || fat_val == 0xffff)
- break;
-
entry = fat_val;
}
@@ -750,7 +793,9 @@
*gotsize += actsize;
/* Mark end of file in FAT */
- if (mydata->fatsize == 16)
+ if (mydata->fatsize == 12)
+ newclust = 0xfff;
+ else if (mydata->fatsize == 16)
newclust = 0xffff;
else if (mydata->fatsize == 32)
newclust = 0xfffffff;