[U-Boot] [PATCH V2 5/5] fat: implement exists() for FAT fs

[Simon Glass]

Hi Stephen,

On 23 January 2014 12:57, Stephen Warren <swarren at wwwdotorg.org> wrote:

> From: Stephen Warren <swarren at nvidia.com>
>
> This hooks into the generic "file exists" support added in an earlier
> patch, and provides an implementation for the ext4 filesystem.
>

s/ext4/fat


>
> Signed-off-by: Stephen Warren <swarren at nvidia.com>
> ---
> v2: s/ext/fat/ in the commit subject
> ---
>  fs/fat/fat.c  | 18 ++++++++++++++----
>  fs/fs.c       |  2 +-
>  include/fat.h |  1 +
>  3 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/fs/fat/fat.c b/fs/fat/fat.c
> index b41d62e3c386..bc06c0a3c688 100644
> --- a/fs/fat/fat.c
> +++ b/fs/fat/fat.c
> @@ -808,7 +808,7 @@ __u8 do_fat_read_at_block[MAX_CLUSTSIZE]
>
>  long
>  do_fat_read_at(const char *filename, unsigned long pos, void *buffer,
> -              unsigned long maxsize, int dols)
> +              unsigned long maxsize, int dols, int dogetsize)
>

I think it would be better to combine the three available operations (read,
ls and getsize) into an enum and pass the required operation explicitly
into this function in a single parameter.


>  {
>         char fnamecopy[2048];
>         boot_sector bs;
> @@ -1152,7 +1152,10 @@ rootdir_done:
>                         subname = nextname;
>         }
>
> -       ret = get_contents(mydata, dentptr, pos, buffer, maxsize);
> +       if (dogetsize)
> +               ret = FAT2CPU32(dentptr->size);
> +       else
> +


Doesn't this mean you are actually reading the contents here into a NULL
buffer? At least I think it needs a comment as to why this works.


> ret = get_contents(mydata, dentptr, pos, buffer, maxsize);
>         debug("Size: %d, got: %ld\n", FAT2CPU32(dentptr->size), ret);
>
>  exit:
> @@ -1163,7 +1166,7 @@ exit:
>  long
>  do_fat_read(const char *filename, void *buffer, unsigned long maxsize,
> int dols)
>  {
> -       return do_fat_read_at(filename, 0, buffer, maxsize, dols);
> +       return do_fat_read_at(filename, 0, buffer, maxsize, dols, 0);
>  }
>
>  int file_fat_detectfs(void)
> @@ -1233,11 +1236,18 @@ int file_fat_ls(const char *dir)
>         return do_fat_read(dir, NULL, 0, LS_YES);
>  }
>
> +int fat_exists(const char *filename)
> +{
> +       int sz;
> +       sz = do_fat_read_at(filename, 0, NULL, 0, LS_NO, 1);
> +       return (sz >= 0) ? 0 : 1;
> +}
> +
>  long file_fat_read_at(const char *filename, unsigned long pos, void
> *buffer,
>                       unsigned long maxsize)
>  {
>         printf("reading %s\n", filename);
> -       return do_fat_read_at(filename, pos, buffer, maxsize, LS_NO);
> +       return do_fat_read_at(filename, pos, buffer, maxsize, LS_NO, 0);
>  }
>
>  long file_fat_read(const char *filename, void *buffer, unsigned long
> maxsize)
> diff --git a/fs/fs.c b/fs/fs.c
> index 3f14d0169b43..d2bc8d0f1459 100644
> --- a/fs/fs.c
> +++ b/fs/fs.c
> @@ -80,7 +80,7 @@ static struct fstype_info fstypes[] = {
>                 .probe = fat_set_blk_dev,
>                 .close = fat_close,
>                 .ls = file_fat_ls,
> -               .exists = fs_exists_unsupported,
> +               .exists = fat_exists,
>                 .read = fat_read_file,
>                 .write = fs_write_unsupported,
>         },
> diff --git a/include/fat.h b/include/fat.h
> index 2c951e7d79c6..c8eb7ccd2904 100644
> --- a/include/fat.h
> +++ b/include/fat.h
> @@ -188,6 +188,7 @@ file_read_func              file_fat_read;
>  int file_cd(const char *path);
>  int file_fat_detectfs(void);
>  int file_fat_ls(const char *dir);
> +int fat_exists(const char *filename);
>  long file_fat_read_at(const char *filename, unsigned long pos, void
> *buffer,
>                       unsigned long maxsize);
>  long file_fat_read(const char *filename, void *buffer, unsigned long
> maxsize);
> --
> 1.8.1.5
>
>
Regards,
Simon