[U-Boot] [PATCH] FAT: fix some issues in FAT write support code

[Anatolij Gustschin]

Writing a file to the FAT partition didn't work while a
test using a CF card. The test was done on mpc5200 based
board (powerpc). There is a number of problems in FAT
write code:

Compiler warning:
fat_write.c: In function 'file_fat_write':
fat_write.c:326: warning: 'counter' may be used uninitialized
in this function
fat_write.c:326: note: 'counter' was declared here

'l_filename' string is not terminated, so a file name
with garbage at the end is used as a file name as shown
by debug code.

Return value of set_contents() is not checked properly
so actually a file won't be written at all (as checked
using 'fatls' after a write attempt with 'fatwrite'
command).

do_fat_write() doesn't return the number of written bytes
if no error happened. However the return value of this
function is used to show the number of written bytes
in do_fat_fswrite().

The patch adds some debug code and fixes above mentioned
problems and also fixes a typo in error output.

NOTE: after a successful write to the FAT partition (under
U-Boot) the partition was checked under Linux using fsck.
The partition needed fixing FATs:
-bash-3.2# fsck -a /dev/sda1
fsck 1.39 (29-May-2006)
dosfsck 2.11, 12 Mar 2005, FAT32, LFN
FATs differ but appear to be intact. Using first FAT.
Performing changes.

Signed-off-by: Anatolij Gustschin <agust at denx.de>
Cc: Donggeun Kim <dg77.kim at samsung.com>
Cc: Aaron Williams <Aaron.Williams at cavium.com>
---
 fs/fat/fat_write.c |   19 ++++++++++++++-----
 1 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 4f1772f..3542b0b 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -323,7 +323,7 @@ static void
 fill_dir_slot(fsdata *mydata, dir_entry **dentptr, const char *l_name)
 {
 	dir_slot *slotptr = (dir_slot *)get_vfatname_block;
-	__u8 counter, checksum;
+	__u8 counter = 0, checksum;
 	int idx = 0, ret;
 	char s_name[16];
 
@@ -926,6 +926,7 @@ static int do_fat_write(const char *filename, void *buffer,
 	int cursect;
 	int root_cluster, ret = -1, name_len;
 	char l_filename[VFAT_MAXLEN_BYTES];
+	int write_size = size;
 
 	dir_curclust = 0;
 
@@ -985,7 +986,11 @@ static int do_fat_write(const char *filename, void *buffer,
 	dentptr = (dir_entry *) do_fat_read_block;
 
 	name_len = strlen(filename);
+	if (name_len >= VFAT_MAXLEN_BYTES)
+		name_len = VFAT_MAXLEN_BYTES - 1;
+
 	memcpy(l_filename, filename, name_len);
+	l_filename[name_len] = 0; /* terminate the string */
 	downcase(l_filename);
 
 	startsect = mydata->rootdir_sect;
@@ -1012,10 +1017,12 @@ static int do_fat_write(const char *filename, void *buffer,
 		}
 
 		ret = set_contents(mydata, retdent, buffer, size);
-		if (ret) {
+		if (ret < 0) {
 			printf("Error: writing contents\n");
 			goto exit;
 		}
+		write_size = ret;
+		debug("attempt to write 0x%x bytes\n", write_size);
 
 		/* Flush fat buffer */
 		ret = flush_fat_buffer(mydata);
@@ -1029,7 +1036,7 @@ static int do_fat_write(const char *filename, void *buffer,
 			    get_dentfromdir_block,
 			    mydata->clust_size * mydata->sect_size);
 		if (ret) {
-			printf("Error: wrinting directory entry\n");
+			printf("Error: writing directory entry\n");
 			goto exit;
 		}
 	} else {
@@ -1056,10 +1063,12 @@ static int do_fat_write(const char *filename, void *buffer,
 			start_cluster, size, 0x20);
 
 		ret = set_contents(mydata, empty_dentptr, buffer, size);
-		if (ret) {
+		if (ret < 0) {
 			printf("Error: writing contents\n");
 			goto exit;
 		}
+		write_size = ret;
+		debug("attempt to write 0x%x bytes\n", write_size);
 
 		/* Flush fat buffer */
 		ret = flush_fat_buffer(mydata);
@@ -1080,7 +1089,7 @@ static int do_fat_write(const char *filename, void *buffer,
 
 exit:
 	free(mydata->fatbuf);
-	return ret;
+	return ret < 0 ? ret : write_size;
 }
 
 int file_fat_write(const char *filename, void *buffer, unsigned long maxsize)
-- 
1.7.1