Don't assume that boot commands will only return on fail

While it's true that for most loaders the boot command never returns, it
may be the case that it does. For example the GRUB emulator boot command
calls to systemctl kexec which in turn does an asynchonous call to kexec.

So in this case GRUB will wrongly assume that the boot command fails and
print a "Failed to boot both default and fallback entries" even when the
kexec call later succeeds.

Signed-off-by: Javier Martinez Canillas <[email protected]>

grub-core/normal/menu.c

@@ -285,7 +285,7 @@ get_and_remove_first_entry_number (grub_menu_t menu, const char *name)
 }
 
 /* Run a menu entry.  */
-static void
+static grub_err_t
 grub_menu_execute_entry(grub_menu_entry_t entry, int auto_boot)
 {
   grub_err_t err = GRUB_ERR_NONE;
@@ -302,7 +302,7 @@ grub_menu_execute_entry(grub_menu_entry_t entry, int auto_boot)
     {
       grub_print_error ();
       grub_errno = GRUB_ERR_NONE;
-      return;
+      return grub_errno;
     }
 
   errs_before = grub_err_printed_errors;
@@ -315,7 +315,7 @@ grub_menu_execute_entry(grub_menu_entry_t entry, int auto_boot)
       grub_env_context_open ();
       menu = grub_zalloc (sizeof (*menu));
       if (! menu)
-	return;
+	return grub_errno;
       grub_env_set_menu (menu);
       if (auto_boot)
 	grub_env_set ("timeout", "0");
@@ -385,7 +385,7 @@ grub_menu_execute_entry(grub_menu_entry_t entry, int auto_boot)
 
   if (grub_errno == GRUB_ERR_NONE && grub_loader_is_loaded ())
     /* Implicit execution of boot, only if something is loaded.  */
-    grub_command_execute ("boot", 0, 0);
+    err = grub_command_execute ("boot", 0, 0);
 
   if (errs_before != grub_err_printed_errors)
     grub_wait_after_message ();
@@ -408,6 +408,8 @@ grub_menu_execute_entry(grub_menu_entry_t entry, int auto_boot)
   else
     grub_env_unset ("default");
   grub_env_unset ("timeout");
+
+  return err;
 }
 
 /* Execute ENTRY from the menu MENU, falling back to entries specified
@@ -422,10 +424,13 @@ grub_menu_execute_with_fallback (grub_menu_t menu,
 				 void *callback_data)
 {
   int fallback_entry;
+  grub_err_t err;
 
   callback->notify_booting (entry, callback_data);
 
-  grub_menu_execute_entry (entry, 1);
+  err = grub_menu_execute_entry (entry, 1);
+  if (err == GRUB_ERR_NONE)
+    return;
 
   /* Deal with fallback entries.  */
   while ((fallback_entry = get_and_remove_first_entry_number (menu, "fallback"))
@@ -436,11 +441,9 @@ grub_menu_execute_with_fallback (grub_menu_t menu,
 
       entry = grub_menu_get_entry (menu, fallback_entry);
       callback->notify_fallback (entry, callback_data);
-      grub_menu_execute_entry (entry, 1);
-      /* If the function call to execute the entry returns at all, then this is
-	 taken to indicate a boot failure.  For menu entries that do something
-	 other than actually boot an operating system, this could assume
-	 incorrectly that something failed.  */
+      err = grub_menu_execute_entry (entry, 1);
+      if (err == GRUB_ERR_NONE)
+        return;
     }
 
   if (!autobooted)