linux-kernel - Re: [PATCH] Staging: TIDSPBRIDGE: Remove UUID helper

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Message-ID: <1385924770.2664.14.camel@joe-AO722>
Date:	Sun, 01 Dec 2013 11:06:10 -0800
From:	Joe Perches <joe@...ches.com>
To:	Ivaylo DImitrov <ivo.g.dimitrov.75@...il.com>
Cc:	omar.ramirez@...itl.com, gregkh@...uxfoundation.org,
	pali.rohar@...il.com, pavel@....cz, linux-kernel@...r.kernel.org,
	devel@...verdev.osuosl.org, Ivaylo Dimitrov <freemangordon@....bg>
Subject: Re: [PATCH] Staging: TIDSPBRIDGE: Remove UUID helper

On Sun, 2013-12-01 at 19:07 +0200, Ivaylo DImitrov wrote:
> From: Ivaylo Dimitrov <freemangordon@....bg>
> 
> Custom uuid helper function is needed only in rmgr/dbdcd.c and doesn't
> need to be exported. It can also be made way simpler by using sscanf.
[]
> diff --git a/drivers/staging/tidspbridge/rmgr/dbdcd.c b/drivers/staging/tidspbridge/rmgr/dbdcd.c
[]
> @@ -74,6 +74,40 @@ static int get_dep_lib_info(struct dcd_manager *hdcd_mgr,
>  				   enum nldr_phase phase);
>  
>  /*
> + *  ======== dcd_uuid_from_string ========
> + *  Purpose:
> + *      Converts an ANSI string to a dsp_uuid.
> + *  Parameters:
> + *      sz_uuid:    Pointer to a string that represents a dsp_uuid object.
> + *      uuid_obj:      Pointer to a dsp_uuid object.
> + *  Returns:
> + *  Requires:
> + *      uuid_obj & sz_uuid are non-NULL values.
> + *  Ensures:
> + *  Details:
> + *      We assume the string representation of a UUID has the following format:
> + *      "12345678_1234_1234_1234_123456789abc".
> + */
> +static void dcd_uuid_from_string(char *sz_uuid, struct dsp_uuid *uuid_obj)
> +{
> +	char c;
> +	u64 t;
> +
> +	/*
> +	 * sscanf implementation cannot deal with hh format modifier
> +	 * if the converted value doesn't fit in u32. So, convert the
> +	 * last six bytes to u64 and memcpy what is needed
> +	 */
> +	sscanf(sz_uuid, "%8x%c%4hx%c%4hx%c%2hhx%2hhx%c%llx",
> +	       &uuid_obj->data1, &c, &uuid_obj->data2, &c,
> +	       &uuid_obj->data3, &c, &uuid_obj->data4,
> +	       &uuid_obj->data5, &c, &t);
> +
> +	t = cpu_to_be64(t);
> +	memcpy(&uuid_obj->data6[0], ((char*)&t) + 2, 6);
> +}

It'd probably be better to return true or false on
successful conversion, use a temporary struct dsp_uuid,
check the sscanf return is 10 and only copy to uuid_obj
on success.

Something like:

static bool dcd_uuid_from_string(char *sz_uuid, struct dsp_uuid *uuid_obj)
{
	char c;
	u64 t;
	struct dsp_uuid tmp;

	/*
	 * sscanf implementation cannot deal with hh format modifier
	 * if the converted value doesn't fit in u32. So, convert the
	 * last six bytes to u64 and memcpy what is needed
	 */
	if (sscanf(sz_uuid, "%8x%c%4hx%c%4hx%c%2hhx%2hhx%c%llx",
		   &tmp.data1, &c, &tmp.data2, &c,
		   &tmp.data3, &c, &tmp.data4,
		   &tmp.data5, &c, &t) != 10)
		return false;

	t = cpu_to_be64(t);
	memcpy(&tmp.data6[0], ((char*)&t) + 2, 6);
	*uuid_obj =  tmp;

	return true;
}


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