linux-kernel - Re: [PATCH v4 1/2] mm: add kstrimdup function

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Date:	Wed, 29 Jan 2014 19:50:59 -0800
From:	Joe Perches <joe@...ches.com>
To:	Sebastian Capella <sebastian.capella@...aro.org>
Cc:	Mikulas Patocka <mpatocka@...hat.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-pm@...r.kernel.org, linaro-kernel@...ts.linaro.org,
	patches@...aro.org, Andrew Morton <akpm@...ux-foundation.org>,
	Michel Lespinasse <walken@...gle.com>,
	Shaohua Li <shli@...nel.org>,
	Jerome Marchand <jmarchan@...hat.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v4 1/2] mm: add kstrimdup function

On Wed, 2014-01-29 at 19:41 -0800, Sebastian Capella wrote:
> Quoting Joe Perches (2014-01-29 17:24:28)
> > Why not minimize the malloc length too?
> > 

> I figured it would be mostly for small trimming, but it seems like
> it could be and advantage and used more generally this way.
> 
> I have a couple of small changes to return NULL in empty string/all ws
> cases and fix a buffer underrun.
> 
> How does this look?
[]
> char *kstrimdup(const char *s, gfp_t gfp)
> {                                                                                
>         char *buf;                                                               
>         const char *begin = skip_spaces(s);                                      
>         size_t len = strlen(begin);                                              

removing begin and just using s would work

>         if (len == 0)                                                            
>                 return NULL;                                                     
>                                                                                  
>         while (len > 1 && isspace(begin[len - 1]))                               
>                 len--;                                                           
>                                                                                  
>         buf = kmalloc_track_caller(len + 1, gfp);                                
>         if (!buf)                                                                
>                 return NULL;                                                     
>                                                                                  
>         memcpy(buf, begin, len);                                                 
>         buf[len] = '\0';                                                            
>                                                                                  
>         return buf;                                                              
> }

What should the return be to this string?

" "

Should it be "" or " " or NULL?

I don't think it should be NULL.
I don't think it should be " ".

cheers, Joe

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