Re: [Qemu-devel] [PATCH V9 2/4] block: Add check infinite loop in bdrv_img_create()

[Jeff Cody]

On Tue, Nov 26, 2013 at 01:38:31AM -0500, Xu Wang wrote:
> Backing file loop should be checked before qemu-img create command
> execution. If loop is found, qemu-img create should be stopped and
> an error printed.
> 
> Signed-off-by: Xu Wang <address@hidden>
> ---
>  block.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 7016ce8..b8cea1c 100644
> --- a/block.c
> +++ b/block.c
> @@ -4633,14 +4633,6 @@ void bdrv_img_create(const char *filename, const char 
> *fmt,
>      }
>  
>      backing_file = get_option_parameter(param, BLOCK_OPT_BACKING_FILE);
> -    if (backing_file && backing_file->value.s) {
> -        if (!strcmp(filename, backing_file->value.s)) {
> -            error_setg(errp, "Error: Trying to create an image with the "
> -                             "same filename as the backing file");
> -            goto out;
> -        }
> -    }
> -
>      backing_fmt = get_option_parameter(param, BLOCK_OPT_BACKING_FMT);
>      if (backing_fmt && backing_fmt->value.s) {
>          backing_drv = bdrv_find_format(backing_fmt->value.s);
> @@ -4651,6 +4643,16 @@ void bdrv_img_create(const char *filename, const char 
> *fmt,
>          }
>      }
>  
> +    if (backing_file && backing_file->value.s) {
> +        if (!bdrv_backing_chain_okay(backing_file->value.s,
> +                                     backing_drv, filename,
> +                                     &local_err)) {
> +            error_setg(errp, "Failed to create image: %s",
> +                       error_get_pretty(local_err));
> +            goto out;

This one is OK, because at out: there is an error_propagate(), which will
see that errp is already set, and just free local_err at that point.

> +        }
> +    }
> +
>      // The size for the image must always be specified, with one exception:
>      // If we are using a backing file, we can obtain the size from there
>      size = get_option_parameter(param, BLOCK_OPT_SIZE);
> -- 
> 1.8.1.4
> 
>