diff mbox

[U-Boot,v2] fat: fatwrite: fix the command for FAT12

Message ID 1481835173-14591-1-git-send-email-philipp.skadorov@savoirfairelinux.com
State Accepted
Commit 49abbd9cc309235895c9ff7ccb6ad75c40fca4a9
Delegated to: Tom Rini
Headers show

Commit Message

Philipp Skadorov Dec. 15, 2016, 8:52 p.m. UTC 
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>
---
 fs/fat/fat_write.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 53 insertions(+), 8 deletions(-)

Comments

Tom Rini Dec. 27, 2016, 10:57 p.m. UTC | #1 
On Thu, Dec 15, 2016 at 03:52:53PM -0500, Philipp Skadorov wrote:

> 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>

Applied to u-boot/master, thanks!
diff mbox

Patch

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 @@  get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster,
 }
 
 /*
- * 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 @@  static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
 		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 @@  static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
 	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 @@  static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
 }
 
 /*
- * 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 @@  static void flush_dir_table(fsdata *mydata, dir_entry **dentptr)
 		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 @@  static int clear_fatent(fsdata *mydata, __u32 entry)
 {
 	__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 @@  set_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer,
 		*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;