Re: [PATCH] cmp: Only return success when both files have the same contents

[Daniel Kiper]

On Sat, Oct 01, 2022 at 12:44:50AM -0500, Glenn Washburn wrote:
> On Thu, 29 Sep 2022 16:00:59 +0200
> Daniel Kiper <dkiper@net-space.pl> wrote:
>
> > On Thu, Aug 25, 2022 at 07:56:29PM -0500, Glenn Washburn wrote:
> > > From: Li Gen <ligenlive@gmail.com>
> > >
> > > This allows the cmp command to be used in GRUB scripts to conditionally
> > > run commands based on whether two files are the same.
> > >
> > > Signed-off-by: Li Gen <ligenlive@gmail.com>
> > > Signed-off-by: Glenn Washburn <development@efficientek.com>
> > > ---
> > >  grub-core/commands/cmp.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/grub-core/commands/cmp.c b/grub-core/commands/cmp.c
> > > index e9c3b25d34..e1665cf27b 100644
> > > --- a/grub-core/commands/cmp.c
> > > +++ b/grub-core/commands/cmp.c
> > > @@ -38,6 +38,7 @@ grub_cmd_cmp (grub_command_t cmd __attribute__ 
> > > ((unused)),
> > >    grub_file_t file2 = 0;
> > >    char *buf1 = 0;
> > >    char *buf2 = 0;
> > > +  grub_err_t err = GRUB_ERR_TEST_FAILURE;
> > >
> > >    if (argc != 2)
> > >      return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("two arguments 
> > > expected"));
> > > @@ -91,6 +92,7 @@ grub_cmd_cmp (grub_command_t cmd __attribute__ 
> > > ((unused)),
> > >
> > >        /* TRANSLATORS: it's always exactly 2 files.  */
> > >        grub_printf_ (N_("The files are identical.\n"));
> >
> > I think we should add a quite option to not switch video mode if it is
> > not needed. And these new cmp features should be mentioned in doc.
>
> To adding a quiet mode, I completely agree and thought about adding it.
> I decided against it in this patch because it didn't seem related. I
> might get around to doing it, but it could be a while. What do you
> think about having instead a verbose mode, and the default being quiet?

Yeah, I thought about it too. Go for it!.

> Since doing some logic based on cmp output should not really be
> happening, I don't think this should be a problem, only might cause
> some people not to see expected output.

Yep, but I do not expect many users of cmp command right now...

> As for a documentation update, agreed. I try to find some time this
> week to submit a v2 adding the documentation.

Cool! Thanks!

Daniel