On Tue, Dec 22, 2020 at 3:09 PM Alexandru Ardelean
<alexandru.ardelean@xxxxxxxxxx> wrote:
>
> The original docstring of the __sysfs_match_string() and match_string()
> helper, implied that -1 could be used to search through NULL terminated
> arrays, and positive 'n' could be used to go through arrays that may have
> NULL elements in the middle of the array.
>
> This isn't true. Regardless of the value of 'n', the first NULL element in
> the array will stop the search, even if the element may be after a NULL
> element.
>
> To allow for a behavior where we can use the __sysfs_match_string() to
> search over arrays with NULL elements in the middle, the
> __sysfs_match_string_with_gaps() helper is added.
> If n > 0, the search will continue until the element is found or n is
> reached.
> If n < 0, the search will continue until the element is found or a NULL
> character is found.
I'm wondering if we can leave __sysfs_match_string() alone (w/o adding
unnecessary branch).
int __sysfs_match_string_with_gaps(const char * const *array, size_t
n, const char *str)
{
const char *item;
int index;
for (index = 0; index < n; index++) {
item = array[index];
if (!item)
continue;
if (sysfs_streq(item, str))
return index;
}
return -EINVAL;
}
Note, the check n>0 seems redundant for this particular function.
> +static int __sysfs_match_string_common(const char * const *array, ssize_t n,
> + const char *str, bool gaps)
> +{
> + const char *item;
> + int index;
> +
> + for (index = 0; index < n; index++) {
> + item = array[index];
> + if (!item) {
> + if (gaps && n > 0)
> + continue;
> + break;
> + }
> + if (sysfs_streq(item, str))
> + return index;
> + }
> +
> + return -EINVAL;
> +}
> +
> /**
> * __sysfs_match_string - matches given string in an array
> * @array: array of strings
> @@ -770,21 +790,32 @@ EXPORT_SYMBOL(match_string);
> */
> int __sysfs_match_string(const char * const *array, size_t n, const char *str)
> {
> - const char *item;
> - int index;
> -
> - for (index = 0; index < n; index++) {
> - item = array[index];
> - if (!item)
> - break;
> - if (sysfs_streq(item, str))
> - return index;
> - }
> -
> - return -EINVAL;
> + return __sysfs_match_string_common(array, n, str, false);
> }
--
With Best Regards,
Andy Shevchenko
