[Skiboot] [PATCH] external/pflash: Fix non-zero return code for successful read when size%256 != 0

[Cyril Bur]

On Fri, 2017-12-01 at 13:41 +1100, Suraj Jitindar Singh wrote:
> When performing a read the return value from pflash is non-zero, even for
> a successful read, when the size being read is not a multiple of 256.
> This is because do_read_file returns the value from the write system
> call which is then returned by pflash. When the size is a multiple of
> 256 we get lucky in that this wraps around back to zero. However for any
> other value the return code is size % 256. This means even when the
> operation is successful the return code will seem to reflect an error.
> 
> Fix this by returning zero if the entire size was read correctly,
> otherwise return the corresponding error code.
> 
> Fixes: e1cf130d ("external/pflash: Remove use of exit() and fix memory leaks")
> 
> Reported-by: Pridhiviraj Paidipeddi <ppaidipe at linux.vnet.ibm.com>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh at gmail.com>

Reviewed-by: Cyril Bur <cyrilbur at gmail.com>

> ---
>  external/pflash/pflash.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/external/pflash/pflash.c b/external/pflash/pflash.c
> index 381df24f..a5e7bc35 100644
> --- a/external/pflash/pflash.c
> +++ b/external/pflash/pflash.c
> @@ -511,7 +511,7 @@ static int do_read_file(struct blocklevel_device *bl, const char *file,
>  	}
>  	progress_end();
>  	close(fd);
> -	return rc;
> +	return size ? rc : 0;
>  }
>  
>  static int enable_4B_addresses(struct blocklevel_device *bl)