[PATCH v4 4/5] efi: Print an error if boot to firmware setup is not supported

[Robbie Harwood]

From: Javier Martinez Canillas <javierm@redhat.com>

The "fwsetup" command is only registered if the firmware supports booting
to the firmware setup UI. But it could be possible that the GRUB config
already contains a "fwsetup" entry, because it was generated in a machine
that has support for this feature.

To prevent users getting an error like:

    error: ../../grub-core/script/function.c:109:can't find command `fwsetup'.

if it is not supported by the firmware, let's just always register the
command but print a more accurate message if the firmware doesn't
support this option.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Robbie Harwood <rharwood@redhat.com>
---
 grub-core/commands/efi/efifwsetup.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/grub-core/commands/efi/efifwsetup.c 
b/grub-core/commands/efi/efifwsetup.c
index 51bb2ace3b..cb4b6ff18c 100644
--- a/grub-core/commands/efi/efifwsetup.c
+++ b/grub-core/commands/efi/efifwsetup.c
@@ -27,6 +27,8 @@
 
 GRUB_MOD_LICENSE ("GPLv3+");
 
+static grub_efi_boolean_t efifwsetup_is_supported (void);
+
 static grub_err_t
 grub_cmd_fwsetup (grub_command_t cmd __attribute__ ((unused)),
                  int argc __attribute__ ((unused)),
@@ -38,6 +40,10 @@ grub_cmd_fwsetup (grub_command_t cmd __attribute__ 
((unused)),
   grub_size_t oi_size;
   static grub_efi_guid_t global = GRUB_EFI_GLOBAL_VARIABLE_GUID;
 
+  if (!efifwsetup_is_supported ())
+         return grub_error (GRUB_ERR_INVALID_COMMAND,
+                            N_("reboot to firmware setup is not supported by 
the current firmware"));
+
   grub_efi_get_variable ("OsIndications", &global, &oi_size,
                         (void **) &old_os_indications);
 
@@ -82,10 +88,8 @@ efifwsetup_is_supported (void)
 
 GRUB_MOD_INIT (efifwsetup)
 {
-  if (efifwsetup_is_supported ())
-    cmd = grub_register_command ("fwsetup", grub_cmd_fwsetup, NULL,
-                                N_("Reboot into firmware setup menu."));
-
+  cmd = grub_register_command ("fwsetup", grub_cmd_fwsetup, NULL,
+                               N_("Reboot into firmware setup menu."));
 }
 
 GRUB_MOD_FINI (efifwsetup)
-- 
2.35.1