Re: [PATCH v5 1/2] mm: add kstrimdup function

[Sebastian Capella <sebastian.capella@linaro.org>]

Quoting Andrew Morton (2014-01-30 13:22:51)
> On Thu, 30 Jan 2014 13:11:57 -0800 Sebastian Capella <sebastian.capella@linaro.org> wrote:
> > +char *kstrimdup(const char *s, gfp_t gfp)
> > +{
> > +     char *buf;
> > +     char *begin = skip_spaces(s);
> > +     size_t len = strlen(begin);
> > +
> > +     while (len > 1 && isspace(begin[len - 1]))
> > +             len--;
> 
> That's off-by-one isn't it?  kstrimdup("   ") should return "", not " ".
> 
> > +     buf = kmalloc_track_caller(len + 1, gfp);
> > +     if (!buf)
> > +             return NULL;
> > +
> > +     memcpy(buf, begin, len);
> > +     buf[len] = '\0';
> > +
> > +     return buf;
> > +}

Hi Andrew,

I think this is a little tricky.

For an empty string, the function relies on skip_spaces to point begin
at the \0'.

Alternately, if we don't have an empty string, we know we have at least 1
non-space, non-null character at begin[0], and there's no need to check it,
so the loop stops at [1].  If there's a space at 1, we just put the '\0'
there.

We could check at [0], but I think its already been checked by skip_spaces.

I'll add a comment above the while for that

Thanks,

Sebastian


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