From: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> Subject: lib/string.c: update match_string() doc-strings with correct behavior There were a few attempts at changing behavior of the match_string() helpers (i.e. 'match_string()' & 'sysfs_match_string()'), to change & extend the behavior according to the doc-string. But the simplest approach is to just fix the doc-strings. The current behavior is fine as-is, and some bugs were introduced trying to fix it. As for extending the behavior, new helpers can always be introduced if needed. The match_string() helpers behave more like 'strncmp()' in the sense that they go up to n elements or until the first NULL element in the array of strings. This change updates the doc-strings with this info. Link: http://lkml.kernel.org/r/20200213072722.8249-1-alexandru.ardelean@xxxxxxxxxx Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> Acked-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: "Tobin C . Harding" <tobin@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/string.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) --- a/lib/string.c~lib-string-update-match_string-doc-strings-with-correct-behavior +++ a/lib/string.c @@ -699,6 +699,14 @@ EXPORT_SYMBOL(sysfs_streq); * @n: number of strings in the array or -1 for NULL terminated arrays * @string: string to match with * + * This routine will look for a string in an array of strings up to the + * n-th element in the array or until the first NULL element. + * + * Historically the value of -1 for @n, was used to search in arrays that + * are NULL terminated. However, the function does not make a distinction + * when finishing the search: either @n elements have been compared OR + * the first NULL element was found. + * * Return: * index of a @string in the @array if matches, or %-EINVAL otherwise. */ @@ -727,6 +735,14 @@ EXPORT_SYMBOL(match_string); * * Returns index of @str in the @array or -EINVAL, just like match_string(). * Uses sysfs_streq instead of strcmp for matching. + * + * This routine will look for a string in an array of strings up to the + * n-th element in the array or until the first NULL element. + * + * Historically the value of -1 for @n, was used to search in arrays that + * are NULL terminated. However, the function does not make a distinction + * when finishing the search: either @n elements have been compared OR + * the first NULL element was found. */ int __sysfs_match_string(const char * const *array, size_t n, const char *str) { _
