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

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Message-ID: <20140130034137.2769.50210@capellas-linux>
Date:	Wed, 29 Jan 2014 19:41:37 -0800
From:	Sebastian Capella <sebastian.capella@...aro.org>
To:	Joe Perches <joe@...ches.com>,
	"Mikulas Patocka" <mpatocka@...hat.com>
Cc:	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

Quoting Joe Perches (2014-01-29 17:24:28)
> Why not minimize the malloc length too?
> 
> maybe something like:
> 
> char *kstrimdup(const char *s, gfp_t gfp)
> {
>         char *buf;
>         const char *begin = skip_spaces(s);
>         size_t len = strlen(begin);
> 
>         while (len && 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;
> }

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?

Thanks,

Sebastian


char *kstrimdup(const char *s, gfp_t gfp)
{                                                                                
        char *buf;                                                               
        const char *begin = skip_spaces(s);                                      
        size_t len = strlen(begin);                                              

        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;                                                              
}        



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