Re: [PATCH] btrfs-progs: Improve the parse_size() error message.

[Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>]

-------- Original Message --------
Subject: Re: [PATCH] btrfs-progs: Improve the parse_size() error message.
From: Mike Fleetwood <mike.fleetwood@xxxxxxxxxxxxxx>
To: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
Date: 2014年05月29日 05:07
> On 20 May 2014 08:51, Qu Wenruo <quwenruo@xxxxxxxxxxxxxx> wrote:
> > When using parse_size(), even non-numeric value is passed, it will only
> > give error message "ERROR: size value is empty", which is quite
> > confusing for end users.
> >
> > This patch will introduce more meaningful error message for the
> > following new cases
> > 1) Invalid size string (non-numeric string)
> > 2) Minus size value (like "-1K")
> >
> > Also this patch will take full use of endptr returned by strtoll() to
> > reduce unneeded loop.
> >
> > Reported-by: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
> > Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
> > ---
> >   utils.c | 53 +++++++++++++++++++++++++++++++++--------------------
> >   1 file changed, 33 insertions(+), 20 deletions(-)
> >
> > diff --git a/utils.c b/utils.c
> > index 392c5cf..1cbe102 100644
> > --- a/utils.c
> > +++ b/utils.c
> > @@ -1612,18 +1612,20 @@ scan_again:
> >
> >   u64 parse_size(char *s)
> >   {
> > -       int i;
> >          char c;
> >          u64 mult = 1;
> > -
> > -       for (i = 0; s && s[i] && isdigit(s[i]); i++) ;
> > -       if (!i) {
> > -               fprintf(stderr, "ERROR: size value is empty\n");
> > -               exit(50);
> > -       }
> > -
> > -       if (s[i]) {
> > -               c = tolower(s[i]);
> > +       long long int ret = 0;
> > +       char *endptr;
> > +
> > +       if (!s)
> > +               goto empty;
> > +       ret = strtoll(s, &endptr, 10);
> > +       if (endptr == s)
> > +               goto invalid;
> > +       if (endptr[0] && endptr[1])
> > +               goto suffix;
> > +       if (endptr[0]) {
> > +               c = tolower(endptr[0]);
> >                  switch (c) {
> >                  case 'e':
> >                          mult *= 1024;
> > @@ -1646,18 +1648,29 @@ u64 parse_size(char *s)
> >                  case 'b':
> >                          break;
> >                  default:
> > -                       fprintf(stderr, "ERROR: Unknown size descriptor "
> > -                               "'%c'\n", c);
> > -                       exit(1);
> > +                       goto descriptor;
> >                  }
> >          }
> > -       if (s[i] && s[i+1]) {
> > -               fprintf(stderr, "ERROR: Illegal suffix contains "
> > -                       "character '%c' in wrong position\n",
> > -                       s[i+1]);
> > -               exit(51);
> > -       }
> > -       return strtoull(s, NULL, 10) * mult;
> > +       ret *= mult;
> > +       if (ret <= 0)
> > +               goto minus;
> > +       return (u64) ret;
> > +empty:
> > +       fprintf(stderr, "ERROR: Size value is empty\n");
> > +       exit(50);
> > +suffix:
> > +       fprintf(stderr, "ERROR: Illegal suffix contains character '%c' in wrong position\n",
> > +               endptr[1]);
> > +       exit(51);
> > +descriptor:
> > +       fprintf(stderr, "ERROR: Unknown size descriptor '%c'\n", c);
> > +       exit(52);
> > +invalid:
> > +       fprintf(stderr, "ERROR: Size value '%s' is invalid\n", s);
> > +       exit(53);
> > +minus:
> > +       fprintf(stderr, "ERROR: Size value '%s' is less equal than 0\n", s);
> > +       exit(54);
> >   }
> >
> >   int open_file_or_dir3(const char *fname, DIR **dirstream, int open_flags)
> > --
> > 1.9.2
> IMHO use of this "if condition goto print error exit" pattern makes
> the code harder to read.  Use of gotos is used when a function creates
> state which needs tearing down in reverse on error before returning.
> I think the errors should be printed at the point of detection.  Like
> this:
>
> +       if (!s) {
> +               fprintf(stderr, "ERROR: Size value is empty\n");
> +               exit(1);
> +       }
> +       ret = strtoll(s, &endptr, 10);
> +       if (endptr == s) {
> +               fprintf(stderr, "ERROR: Size value '%s' is invalid\n", s);
> +               exit(1);
> +       }
>
> etc.
>
> Thanks,
> Mike
Yes, that's true. I will change it to the original style.

Thanks,
Qu
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html