Hi Pierre,

Thanks for doing this.  Comments below.

On Sat,  5 May 2012 16:32:30 +0200 Pierre Carrier <pierre@spotify.com> wrote:
>
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index abbabec..7129383 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -284,6 +284,7 @@ char *number(char *buf, char *end, unsigned long long num,
>  	char locase;
>  	int need_pfx = ((spec.flags & SPECIAL) && spec.base != 10);
>  	int i;
> +	bool is_null = num == 0LL;

"num" is a number not a pointer, so I would call it "is_zero" (or just do
the comparisons explicitly below).

>  	/* locase = 0 or 0x20. ORing digits or letters with 'locase'
>  	 * produces same digits or (maybe lowercased) letters */
> @@ -353,9 +354,11 @@ char *number(char *buf, char *end, unsigned long long num,
>  	}
>  	/* "0x" / "0" prefix */
>  	if (need_pfx) {
> -		if (buf < end)
> -			*buf = '0';
> -		++buf;
> +		if (spec.base == 16 || !is_null) {
> +			if (buf < end)
> +				*buf = '0';
> +			++buf;
> +		}
>  		if (spec.base == 16) {
>  			if (buf < end)
>  				*buf = ('X' | locase);

There is also another earlier section that tests "need_pfx" that reduces
the field width.  You should fix that up as well.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/