[U-Boot] [PATCH 1/3] fat: write: fix broken write to fragmented files

[Lukasz Majewski]

Hi Marek,

> The code for handing file overwrite incorrectly assumed that the file
> on disk is always contiguous. This resulted in corrupting disk
> structure every time when write to existing fragmented file happened.
> Fix this by adding proper check for cluster discontinuity and adjust
> chunk size on each partial write.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
> ---
>  fs/fat/fat_write.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
> index 729cf39630d..6cfa5b45652 100644
> --- a/fs/fat/fat_write.c
> +++ b/fs/fat/fat_write.c
> @@ -794,6 +794,8 @@ set_contents(fsdata *mydata, dir_entry *dentptr,
> loff_t pos, __u8 *buffer, 
>  			newclust = get_fatent(mydata, endclust);
>  
> +			if ((newclust - 1) != endclust)
> +				break;
>  			if (IS_LAST_CLUST(newclust, mydata->fatsize))
>  				break;
>  			if (CHECK_CLUST(newclust, mydata->fatsize)) {
> @@ -811,7 +813,7 @@ set_contents(fsdata *mydata, dir_entry *dentptr,
> loff_t pos, __u8 *buffer, offset = 0;
>  		else
>  			offset = pos - cur_pos;
> -		wsize = min(cur_pos + actsize, filesize) - pos;
> +		wsize = min_t(unsigned long long, actsize, filesize
> - cur_pos); if (get_set_cluster(mydata, curclust, offset,
>  				    buffer, wsize, &actsize)) {
>  			printf("Error get-and-setting cluster\n");
> @@ -824,8 +826,6 @@ set_contents(fsdata *mydata, dir_entry *dentptr,
> loff_t pos, __u8 *buffer, if (filesize <= cur_pos)
>  			break;
>  
> -		/* CHECK: newclust = get_fatent(mydata, endclust); */
> -
>  		if (IS_LAST_CLUST(newclust, mydata->fatsize))
>  			/* no more clusters */
>  			break;

Reviewed-by: Lukasz Majewski <lukma at denx.de>

Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma at denx.de
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