lkml.org 
[lkml]   [2014]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2 2/2] lib.c: skip --param parameters
From
Date
On Sat, 2014-06-28 at 09:59 -0700, Christopher Li wrote:
> Oops, I just click send before I type up the reply. Here we go again.
>
> On Tue, Jun 17, 2014 at 2:11 AM, Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> > Very dumb patch to just skip --param allow-store-data-races=0 introduced in
> > newer GCC versions.
> >
> > +static char **handle_param(char *arg, char **next)
> > +{
> > + const char *value = NULL;
> > +
> > + /* For now just skip any '--param=*' or '--param *' */
> > + value = split_value_from_arg(arg, value);
> > + if (!value)
> > + ++next;
> > +
> > + return ++next;
> > +}
>
> I think this is problematic.There are three possible input
> from args:
> 1) "--parm", you need to ++next skip to next arg, which is the value for parm.
> 2) "--parm=x", you don't need to skip to next arg.
> 3) "--parm-with-crap", invalid argument. You don't need to skip next arg.
>
> I think the patch is wrong on case 2) and case 3).
> In case 2), the patch skip two arguments and make next point
> points to out of bound memory.

Hmm... I'd just added test printf to the handle_param() and see if I
print *next, it is either --param or --param=*. So, using return (next +
2) helps, otherwise we end up with the same situation as before patch.

What did I miss?

>
> The split_value_from_arg function is not a good abstraction for this job.
> Its return value can only indicate 2 possible out come.
> Also, returning the default value force the test against the input
> default value. That make the logic a bit complicate.
>
> > struct switches {
> > const char *name;
> > char **(*fn)(char *, char **);
> > @@ -686,13 +698,14 @@ struct switches {
> > static char **handle_long_options(char *arg, char **next)
> > {
> > static struct switches cmd[] = {
> > + { "param", handle_param },
> > { "version", handle_version },
> > { NULL, NULL }
> > };
> > struct switches *s = cmd;
> >
> > while (s->name) {
> > - if (!strcmp(s->name, arg))
> > + if (!strncmp(arg, s->name, strlen(s->name)))
>
> This will allow "--version-with-crap" as valid arguments.

Which was explicitly mentioned in the commit message.

>
> I think we can have one extra member in "struct switch"
> to indicate this option is a prefix rather than a whole word.
> For "parm", it need to set that prefix member to non zero.

No objections about this approach.

> Please let me know if there is a V3 coming.

Apparently you did this on weekend.


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



\
 
 \ /
  Last update: 2014-06-30 11:21    [W:0.113 / U:6.504 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site