[PATCH RFC 2/6] purgatory: No need to sha256 update if ptr->len is zero

[Baoquan He]

On 04/16/15 at 10:17pm, Pratyush Anand wrote:
> If ptr->len is zero we do not need to update sha256.
> 
> Signed-off-by: Pratyush Anand <panand at redhat.com>
> ---
>  purgatory/purgatory.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/purgatory/purgatory.c b/purgatory/purgatory.c
> index 3bbcc0935ad5..f8ed69b8fbfb 100644
> --- a/purgatory/purgatory.c
> +++ b/purgatory/purgatory.c
> @@ -18,6 +18,8 @@ int verify_sha256_digest(void)
>  	sha256_starts(&ctx);
>  	end = &sha256_regions[sizeof(sha256_regions)/sizeof(sha256_regions[0])];
>  	for(ptr = sha256_regions; ptr < end; ptr++) {
> +		if (ptr->len == 0)
> +			continue;

Hi Pratyush,

I don't think this is necessary, but don't object to it strongly.
Since sha256_update will check the length and return immediately if it's
0.

void sha256_update( sha256_context *ctx, const uint8_t *input, size_t
length )
{                             
        size_t left, fill;
 
        if( ! length ) return;

...
}

Thanks
Baoquan

>  		sha256_update(&ctx, (uint8_t *)((uintptr_t)ptr->start),
>  			      ptr->len);
>  	}
> -- 
> 2.1.0
> 
> 
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