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

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

[Glenn Washburn]

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"));
+      err = GRUB_ERR_NONE;
     }
 
 cleanup:
@@ -102,7 +104,7 @@ cleanup:
   if (file2)
     grub_file_close (file2);
 
-  return grub_errno;
+  return err;
 }
 
 static grub_command_t cmd;
-- 
2.34.1

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

[Daniel Kiper]

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.

Daniel

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

[Glenn Washburn]

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?
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.

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

Glenn

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