linux-kernel - Re: [PATCH v2 3/8] lib/uuid: introduce few more generic helpers for UUID

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Date:	Mon, 4 Apr 2016 16:40:29 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:	Arnd Bergmann <arnd@...db.de>, "Theodore Ts'o" <tytso@....edu>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	linux-api@...r.kernel.org
Subject: Re: [PATCH v2 3/8] lib/uuid: introduce few more generic helpers for
 UUID

On Mon,  4 Apr 2016 16:30:05 +0300 Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:

> There are new helpers in this patch:
> 
> uuid_is_valid		checks if a UUID is valid
> uuid_be_to_bin		converts from string to binary (big endian)
> uuid_le_to_bin		converts from string to binary (little endian)
	> 
> They will be used in future, i.e. in the following patches in the series.
> 
> This also moves indices arrays to lib/uuid.c to be shared accross modules.
> 
> ...
>
> --- a/include/linux/uuid.h
> +++ b/include/linux/uuid.h

Nit:

> +/**
> +  * uuid_is_valid - checks if UUID string valid
> +  * @uuid:	UUID string to check
> +  *
> +  * Description:
> +  * It checks if the UUID string is following the format:
> +  *	xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
> +  * where x is a hex digit.
> +  *
> +  * Return: 0 on success, %-EINVAL otherwise.
> +  */
> +int uuid_is_valid(const char *uuid)
> +{
> +	unsigned int i;
> +
> +	if (strnlen(uuid, UUID_STRING_LEN) < UUID_STRING_LEN)
> +		return -EINVAL;
> +
> +	for (i = 0; i < UUID_STRING_LEN; i++) {
> +		if (i == 8 || i == 13 || i == 18 || i == 23) {
> +			if (uuid[i] != '-')
> +				return -EINVAL;
> +		} else if (!isxdigit(uuid[i])) {
> +			return -EINVAL;
> +		}
> +	}

Could add

	if (uuid[i])
		return -EINVAL;

here and lose the additional pass across the input (strlen).

> +	return 0;
> +}
>
> ...
>