Re: [PATCH 1/3][V3] lib: fix __sysfs_match_string() helper when n != -1

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 8 May 2019 14:19:11 +0300
Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:

> The documentation the `__sysfs_match_string()` helper mentions that `n`
> (the size of the given array) should be:
>  * @n: number of strings in the array or -1 for NULL terminated arrays
> 
> The behavior of the function is different, in the sense that it exits on
> the first NULL element in the array.
> 
> This patch changes the behavior, to exit the loop when a NULL element is
> found, and the size of the array is provided as -1.
> 
> All current users of __sysfs_match_string() & sysfs_match_string() provide
> contiguous arrays of strings, so this behavior change doesn't influence
> anything (at this point in time).
> 
> This behavior change allows for an array of strings to have NULL elements
> within the array, which will be ignored. This is particularly useful when
> creating mapping of strings and integers (as bitfields or other HW
> description).
> 
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Looks good to me.  I can take it through IIO given patch 3, but
fine with it taking another route if people would prefer as I don't
think the two 'need' to go together.

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
> 
> Changelog v2 -> v3:
> * fix __sysfs_match_string() vs adding a new
>   __sysfs_match_string_with_gaps() helper
> 
>  lib/string.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/string.c b/lib/string.c
> index 3ab861c1a857..5bea3f98478a 100644
> --- a/lib/string.c
> +++ b/lib/string.c
> @@ -674,8 +674,11 @@ int __sysfs_match_string(const char * const *array, size_t n, const char *str)
>  
>  	for (index = 0; index < n; index++) {
>  		item = array[index];
> -		if (!item)
> +		if (!item) {
> +			if (n != (size_t)-1)
> +				continue;
>  			break;
> +		}
>  		if (sysfs_streq(item, str))
>  			return index;
>  	}