Re: [PATCH] io/attr.c: Disallow specifying both -D and -R options for chattr command

[Eric Sandeen <sandeen@sandeen.net>]

On 7/22/20 11:39 PM, Xiao Yang wrote:
> On 2020/7/23 14:08, Christoph Hellwig wrote:
>> On Thu, Jul 23, 2020 at 01:27:23PM +0800, Xiao Yang wrote:
>>> -D and -R options are mutually exclusive actually but chattr command
>>> doesn't check it so that always applies -D option when both of them
>>> are specified.  For example:
>> Looks good,
>>
>> Reviewed-by: Christoph Hellwig<hch@lst.de>
> Hi,
> 
> Ah,  I have a question after sending the patch:
> Other commands(e.g. cowextsize) including the same options seem to avoid the issue by accepting the last option, as below:
> --------------------------------------------------------
> io/cowextsize.c
> 141         while ((c = getopt(argc, argv, "DR")) != EOF) {
> 142                 switch (c) {
> 143                 case 'D':
> 144                         recurse_all = 0;
> 145                         recurse_dir = 1;
> 146                         break;
> 147                 case 'R':
> 148                         recurse_all = 1;
> 149                         recurse_dir = 0;
> 150                         break;

Yep, I meant to look at this but hadn't gotten to it yet.  These should all
be consistent, and I tend to agree with Dave that explicitly conflicting
incompatible options and erroring out is better than silently accepting
the last one specified.

And indeed help specifies that they are exclusive:

        cowextsize_cmd.args = _("[-D | -R] [cowextsize]");

It'd be great if you want to send a V2 that makes the behavior (and
documentation) of any/all commands that accept [-D | -R] consistent.

Thanks,
-Eric