Re: [Qemu-devel] [RFC 03/24] block: add bdrv_open_conversion_target()

[Stefan Hajnoczi]

On Fri, Jul 29, 2011 at 12:49:33AM -0400, Devin Nakamura wrote:
> +int bdrv_open_conversion_target(BlockDriverState **bs, BlockDriverState 
> *file,
> +                                BlockConversionOptions *drv_options,
> +                                QEMUOptionParameter *usr_options,
> +                                const char *target_fmt)
> +{
> +    BlockDriver *drv;
> +    BlockDriverState *bss;
> +
> +    drv = bdrv_find_format(target_fmt);
> +    if (!drv) {
> +        return -ENOENT;
> +    }
> +
> +    if (!drv->bdrv_open_conversion_target) {
> +        return -ENOTSUP;
> +    }
> +
> +    *bs = bdrv_new("");
> +    bss = *bs;
> +    bss->file = file;
> +    bss->total_sectors = drv_options->image_size >> BDRV_SECTOR_BITS;
> +    bss->encrypted = 0;
> +    bss->valid_key = 0;
> +    bss->open_flags = 0;
> +    /* buffer_alignment defaulted to 512, drivers can change this value */
> +    bss->buffer_alignment = 512;
> +    bss->opaque = qemu_mallocz(drv->instance_size);
> +    bss->drv = drv;
> +    return drv->bdrv_open_conversion_target(bss, drv_options, usr_options);

Normally a function that fails does not leave anything allocated.
Please delete bss and *bs = NULL before returning an error.

Stefan