[PATCH 2/2] efi: Print an error if boot to firmware setup is not supported

[Javier Martinez Canillas]

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 a "can't find command `fwsetup`" error 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>
---

 grub-core/commands/efi/efifwsetup.c | 43 +++++++++++++++--------------
 1 file changed, 23 insertions(+), 20 deletions(-)

diff --git a/grub-core/commands/efi/efifwsetup.c 
b/grub-core/commands/efi/efifwsetup.c
index eaca0328388..328c45e82e0 100644
--- a/grub-core/commands/efi/efifwsetup.c
+++ b/grub-core/commands/efi/efifwsetup.c
@@ -27,6 +27,25 @@
 
 GRUB_MOD_LICENSE ("GPLv3+");
 
+static grub_efi_boolean_t
+efifwsetup_is_supported (void)
+{
+  grub_efi_uint64_t *os_indications_supported = NULL;
+  grub_size_t oi_size = 0;
+  grub_efi_guid_t global = GRUB_EFI_GLOBAL_VARIABLE_GUID;
+
+  grub_efi_get_variable ("OsIndicationsSupported", &global, &oi_size,
+                        (void **) &os_indications_supported);
+
+  if (!os_indications_supported)
+    return 0;
+
+  if (*os_indications_supported & GRUB_EFI_OS_INDICATIONS_BOOT_TO_FW_UI)
+    return 1;
+
+  return 0;
+}
+
 static grub_err_t
 grub_cmd_fwsetup (grub_command_t cmd __attribute__ ((unused)),
                  int argc __attribute__ ((unused)),
@@ -38,6 +57,10 @@ grub_cmd_fwsetup (grub_command_t cmd __attribute__ 
((unused)),
   grub_size_t oi_size;
   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"));
+
   grub_efi_get_variable ("OsIndications", &global, &oi_size,
                         (void **) &old_os_indications);
 
@@ -56,28 +79,8 @@ grub_cmd_fwsetup (grub_command_t cmd __attribute__ 
((unused)),
 
 static grub_command_t cmd = NULL;
 
-static grub_efi_boolean_t
-efifwsetup_is_supported (void)
-{
-  grub_efi_uint64_t *os_indications_supported = NULL;
-  grub_size_t oi_size = 0;
-  grub_efi_guid_t global = GRUB_EFI_GLOBAL_VARIABLE_GUID;
-
-  grub_efi_get_variable ("OsIndicationsSupported", &global, &oi_size,
-                        (void **) &os_indications_supported);
-
-  if (!os_indications_supported)
-    return 0;
-
-  if (*os_indications_supported & GRUB_EFI_OS_INDICATIONS_BOOT_TO_FW_UI)
-    return 1;
-
-  return 0;
-}
-
 GRUB_MOD_INIT (efifwsetup)
 {
-  if (efifwsetup_is_supported ())
     cmd = grub_register_command ("fwsetup", grub_cmd_fwsetup, NULL,
                                 N_("Reboot into firmware setup menu."));
 
-- 
2.31.1