Re: [PATCH v1] sunrpc/cache: convert to use string_escape_str()

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Mon, 2014-12-08 at 17:38 -0500, J. Bruce Fields wrote:
> On Fri, Nov 28, 2014 at 05:50:28PM +0200, Andy Shevchenko wrote:
> > There is nice kernel helper to escape a given strings by provided rules. Let's
> > use it instead of custom approach.
> 
> Looks good, but it broke nfsd.
> 
> After staring at the patch for a while:

> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > ---
> >  net/sunrpc/cache.c | 27 ++++++---------------------
> >  1 file changed, 6 insertions(+), 21 deletions(-)
> > 
> > diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
> > index 0663621..5cf60a4 100644
> > --- a/net/sunrpc/cache.c
> > +++ b/net/sunrpc/cache.c
> > @@ -20,6 +20,7 @@
> >  #include <linux/list.h>
> >  #include <linux/module.h>
> >  #include <linux/ctype.h>
> > +#include <linux/string_helpers.h>
> >  #include <asm/uaccess.h>
> >  #include <linux/poll.h>
> >  #include <linux/seq_file.h>
> > @@ -1067,32 +1068,16 @@ void qword_add(char **bpp, int *lp, char *str)
> >  {
> >  	char *bp = *bpp;
> >  	int len = *lp;
> > -	char c;
> > +	int ret;
> >  
> >  	if (len < 0) return;
> >  
> > -	while ((c=*str++) && len)
> > -		switch(c) {
> > -		case ' ':
> > -		case '\t':
> > -		case '\n':
> > -		case '\\':
> > -			if (len >= 4) {
> > -				*bp++ = '\\';
> > -				*bp++ = '0' + ((c & 0300)>>6);
> > -				*bp++ = '0' + ((c & 0070)>>3);
> > -				*bp++ = '0' + ((c & 0007)>>0);
> > -			}
> > -			len -= 4;
> > -			break;
> > -		default:
> > -			*bp++ = c;
> > -			len--;
> > -		}
> > -	if (c || len <1) len = -1;
> > +	ret = string_escape_str(str, &bp, len, ESCAPE_OCTAL, "\\ \n\t");
> > +	if (ret < 0 || ret == len)
> > +		len = -1;
> >  	else {
> >  		*bp++ = ' ';
> > -		len--;
> > +		len -= ret - 1;
> 
> Looks like that should be ret + 1, not ret - 1.  With that change,
> things work.
> 
> Inclined to actually commit that as:
> 
> 	len -= ret;
> 	*bp++ = ' ';
> 	len--;
> 
> just to make the arithmetic really obvious.
> 
> --b.

Good catch, thanks! It should decrement length indeed. In the form of -=
it must be + 1. Shall I resubmit patch? If so, can I include your tag
(Tested-by I suppose) ?

> 
> >  	}
> >  	*bpp = bp;
> >  	*lp = len;
> > -- 
> > 2.1.3
> > 


-- 
Andy Shevchenko <andriy.shevchenko@intel.com>
Intel Finland Oy