Re: [PATCH 4/4] config: avoid calling `labs()` on too-large data type

[Junio C Hamano <gitster@xxxxxxxxx>]

"Johannes Schindelin via GitGitGadget" <gitgitgadget@xxxxxxxxx>
writes:

> From: Johannes Schindelin <johannes.schindelin@xxxxxx>
>
> The `labs()` function operates, as the initial `l` suggests, on `long`
> parameters. However, in `config.c` we tried to use it on values of type
> `intmax_t`.
>
> This problem was found by GCC v9.x.
>
> To fix it, let's just "unroll" the function (i.e. negate the value if it
> is negative).

Thanks.  Obviously correct.

>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
> ---
>  config.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/config.c b/config.c
> index 296a6d9cc4..01c6e9df23 100644
> --- a/config.c
> +++ b/config.c
> @@ -869,9 +869,9 @@ static int git_parse_signed(const char *value, intmax_t *ret, intmax_t max)
>  			errno = EINVAL;
>  			return 0;
>  		}
> -		uval = labs(val);
> +		uval = val < 0 ? -val : val;
>  		uval *= factor;
> -		if (uval > max || labs(val) > uval) {
> +		if (uval > max || (val < 0 ? -val : val) > uval) {
>  			errno = ERANGE;
>  			return 0;
>  		}