Re: [PATCHv13,1/3] lib/string: add sysfs_match_string helper

[Guenter Roeck]

On Thu, Nov 24, 2016 at 02:21:42PM +0200, Heikki Krogerus wrote:
> Make a simple helper for matching strings with sysfs
> attribute files. In most parts the same as match_string(),
> except sysfs_match_string() uses sysfs_streq() instead of
> strcmp() for matching. This is more convenient when used
> with sysfs attributes.
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
>  include/linux/string.h | 10 ++++++++++
>  lib/string.c           | 26 ++++++++++++++++++++++++++
>  2 files changed, 36 insertions(+)
> 
> diff --git a/include/linux/string.h b/include/linux/string.h
> index 26b6f6a..c4011b2 100644
> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -135,6 +135,16 @@ static inline int strtobool(const char *s, bool *res)
>  }
>  
>  int match_string(const char * const *array, size_t n, const char *string);
> +int __sysfs_match_string(const char * const *array, size_t n, const char *s);
> +
> +/**
> + * sysfs_match_string - matches given string in an array
> + * @_a: array of strings
> + * @_s: string to match with
> + *
> + * Helper for __sysfs_match_string(). Calculates the size of @a automatically.
> + */
> +#define sysfs_match_string(_a, _s) __sysfs_match_string(_a, ARRAY_SIZE(_a), _s)
>  
>  #ifdef CONFIG_BINARY_PRINTF
>  int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);
> diff --git a/lib/string.c b/lib/string.c
> index ed83562..c7a20cb 100644
> --- a/lib/string.c
> +++ b/lib/string.c
> @@ -656,6 +656,32 @@ int match_string(const char * const *array, size_t n, const char *string)
>  }
>  EXPORT_SYMBOL(match_string);
>  
> +/**
> + * __sysfs_match_string - matches given string in an array
> + * @array: array of strings
> + * @n: number of strings in the array or -1 for NULL terminated arrays
> + * @str: string to match with
> + *
> + * Returns index of @str in the @array or -EINVAL, just like match_string().
> + * Uses sysfs_streq instead of strcmp for matching.
> + */
> +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))

No idea how this slipped in: sysfs_streq() returns true on a match,
meaning the "!" here is wrong.

Guenter

> +			return index;
> +	}
> +
> +	return -EINVAL;
> +}
> +EXPORT_SYMBOL(__sysfs_match_string);
> +
>  #ifndef __HAVE_ARCH_MEMSET
>  /**
>   * memset - Fill a region of memory with the given value