Re: [PATCH] Extend index to save more flags

From: Johannes Sixt <j.sixt@viscovery.net>
Date: Sep 1, 2008, 13:05 UTC
Message-ID: <48BBE881.1050206@viscovery.net>
In-Reply-To: <1220268758-29550-1-git-send-email-pclouds@gmail.com>

Nguyễn Thái Ngọc Duy schrieb:

> +/* Extended flags in ondisk_cache_entry_extended */
> +#define CE_EXTENDED2 (0x80000000)
> +#define CE_EXTENDED_MASK (CE_EXTENDED2)

Wouldn't it be better, from a maintainance point of view, to have

#define CE_EXTENDED_MASK 0xffff0000

right from the beginning?

Show 18 quoted lines

> @@ -1143,19 +1144,29 @@ static void convert_from_disk(struct ondisk_cache_entry *ondisk, struct cache_en
>  	/* On-disk flags are just 16 bits */
>  	ce->ce_flags = ntohs(ondisk->flags);
>  
> -	/* For future extension: we do not understand this entry yet */
> -	if (ce->ce_flags & CE_EXTENDED)
> -		die("Unknown index entry format");
>  	hashcpy(ce->sha1, ondisk->sha1);
>  
>  	len = ce->ce_flags & CE_NAMEMASK;
> +
> +	if (ce->ce_flags & CE_EXTENDED) {
> +		struct ondisk_cache_entry_extended *ondisk2;
> +		ondisk2 = (struct ondisk_cache_entry_extended *)ondisk;
> +		ce->ce_flags |= (ntohs(ondisk2->flags2) << 16) & CE_EXTENDED_MASK;
> +		/* For future extension: we do not understand the last bit yet */
> +		if (ce->ce_flags & CE_EXTENDED2)
> +			die("Unknown index entry format");

At this point, we do not understand the CE_EXTENDED2 flag; but we do not understand any of the other 15 extended flags, either. So, you should error out if *any* of them is non-zero.

> +		name = ondisk2->name;
> +	}
> +	else
> +		name = ondisk->name;

-- Hannes