On Mon, Aug 08, 2022 at 08:20:28AM +0200, Ahmad Fatoum wrote:
> In addition to strstarts which we already have, Linux also defines
> str_has_prefix(), which returns the length of the prefix on success and
> zero otherwise. This allows writing straight-forward code to skip over
> a prefix in case it exists. Port it over.
>
> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
> ---
> include/linux/string.h | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
Applied, thanks
Sascha
>
> diff --git a/include/linux/string.h b/include/linux/string.h
> index ae5e5bca8d24..0c79d3e5cf3e 100644
> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -155,4 +155,25 @@ static inline bool strstarts(const char *str, const char *prefix)
> return strncmp(str, prefix, strlen(prefix)) == 0;
> }
>
> +/**
> + * str_has_prefix - Test if a string has a given prefix
> + * @str: The string to test
> + * @prefix: The string to see if @str starts with
> + *
> + * A common way to test a prefix of a string is to do:
> + * strncmp(str, prefix, sizeof(prefix) - 1)
> + *
> + * But this can lead to bugs due to typos, or if prefix is a pointer
> + * and not a constant. Instead use str_has_prefix().
> + *
> + * Returns:
> + * * strlen(@prefix) if @str starts with @prefix
> + * * 0 if @str does not start with @prefix
> + */
> +static __always_inline size_t str_has_prefix(const char *str, const char *prefix)
> +{
> + size_t len = strlen(prefix);
> + return strncmp(str, prefix, len) == 0 ? len : 0;
> +}
> +
> #endif /* _LINUX_STRING_H_ */
> --
> 2.30.2
>
>
>
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