Re: [PATCH v2 6/8] dtc: Fix signedness comparisons warnings: pointer diff

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Fri, Jun 11, 2021 at 06:10:38PM +0100, Andre Przywara wrote:
> With -Wsign-compare, compilers warn about a mismatching signedness
> in comparisons in the function get_node_by_path().
> 
> Taking the difference between two pointers results in a signed ptrdiff_t
> type, which mismatches the unsigned type returned by strlen().
> Since "p" has been returned by a call to strchr() with "path" as its
> argument, we know for sure that it's bigger than "path", so the
> difference must be positive. So a cast to an unsigned type is valid.
> 
> Signed-off-by: Andre Przywara <andre.przywara-5wv7dgnIgG8@public.gmane.org>

Applied, thanks.

> ---
>  livetree.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/livetree.c b/livetree.c
> index cf2f63d..ef141a0 100644
> --- a/livetree.c
> +++ b/livetree.c
> @@ -526,7 +526,7 @@ struct node *get_node_by_path(struct node *tree, const char *path)
>  	p = strchr(path, '/');
>  
>  	for_each_child(tree, child) {
> -		if (p && strprefixeq(path, p - path, child->name))
> +		if (p && strprefixeq(path, (size_t)(p - path), child->name))
>  			return get_node_by_path(child, p+1);
>  		else if (!p && streq(path, child->name))
>  			return child;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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