Add support for LoaderEntryOneshot EFI variable

Index: grub-2.12/grub-core/normal/menu.c
===================================================================
--- grub-2.12.orig/grub-core/normal/menu.c
+++ grub-2.12/grub-core/normal/menu.c
@@ -36,6 +36,16 @@
 #ifdef GRUB_MACHINE_IEEE1275
 #include <grub/ieee1275/ieee1275.h>
 #endif
+#ifdef GRUB_MACHINE_EFI
+#include <grub/charset.h>
+#include <grub/efi/api.h>
+#include <grub/efi/efi.h>
+
+#define GRUB_EFI_LOADER_GUID \
+        { 0x4a67b082, 0x0a4c, 0x41cf, { 0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f } }
+static grub_guid_t grub_efi_loader_guid = GRUB_EFI_LOADER_GUID;
+
+#endif
 
 /* Time to delay after displaying an error message about a default/fallback
    entry failing to boot.  */
@@ -562,6 +572,62 @@ menuentry_eq (const char *id, const char
     }
 }
 
+/* Search for an entry in the menu by its name */
+static int
+search_entry (grub_menu_t menu, const char* name)
+{
+  /* See if the variable matches the title of a menu entry.  */
+  grub_menu_entry_t e = menu->entry_list;
+  int i;
+  int entry;
+
+  /* Skip hidden entries */
+  while (e && e->hidden)
+  e = e->next;
+
+  grub_errno = GRUB_ERR_NONE;
+
+  for (i = 0; e; i++)
+  {
+	if (menuentry_eq (e->title, name)
+		|| menuentry_eq (e->id, name))
+	  {
+		entry = i;
+		break;
+	  }
+
+	if (e->bls)
+	  {
+		char *v, *ext;
+
+		if ((v = grub_strdup (name)) &&
+			(ext = grub_strrchr (v, '.')) &&
+			grub_strcmp (ext, ".conf") == 0)
+		  {
+			*ext = '\0';
+			if (menuentry_eq (e->id, v))
+			  {
+				entry = i;
+				grub_free (v);
+				break;
+			  }
+		  }
+		grub_free (v);
+	  }
+
+	e = e->next;
+
+	/* Skip hidden entries */
+	while (e && e->hidden)
+	  e = e->next;
+  }
+
+  if (! e)
+	entry = -1;
+
+  return entry;
+}
+
 
 /* Get the entry number from the variable NAME.  */
 static int
@@ -580,53 +646,7 @@ get_entry_number (grub_menu_t menu, cons
 
   if (grub_errno == GRUB_ERR_BAD_NUMBER)
     {
-      /* See if the variable matches the title of a menu entry.  */
-      grub_menu_entry_t e = menu->entry_list;
-      int i;
-
-      /* Skip hidden entries */
-      while (e && e->hidden)
-	e = e->next;
-
-      grub_errno = GRUB_ERR_NONE;
-
-      for (i = 0; e; i++)
-	{
-	  if (menuentry_eq (e->title, val)
-	      || menuentry_eq (e->id, val))
-	    {
-	      entry = i;
-	      break;
-	    }
-
-	  if (e->bls)
-	    {
-	      char *v, *ext;
-
-	      if ((v = grub_strdup (val)) &&
-		  (ext = grub_strrchr (v, '.')) &&
-		  grub_strcmp (ext, ".conf") == 0)
-		{
-		  *ext = '\0';
-		  if (menuentry_eq (e->id, v))
-		    {
-		      entry = i;
-		      grub_free (v);
-		      break;
-		    }
-		}
-	      grub_free (v);
-	    }
-
-	  e = e->next;
-
-	  /* Skip hidden entries */
-	  while (e && e->hidden)
-	    e = e->next;
-	}
-
-      if (! e)
-	entry = -1;
+      entry = search_entry (menu, val);
     }
 
   if (grub_errno != GRUB_ERR_NONE)
@@ -724,6 +744,45 @@ run_menu (grub_menu_t menu, int nested,
 
   default_entry = get_entry_number (menu, "default");
 
+#ifdef GRUB_MACHINE_EFI
+  /* verify we are using blscfg */
+  const char* val = grub_env_get ("enable_blscfg");
+  if (val && (val[0] == '1' || val[0] == 'y'))
+	{
+	  grub_efi_status_t status;
+	  int oneshot_entry_index;
+	  grub_efi_char16_t *oneshot_entry_efi = NULL;
+	  char *oneshot_entry = NULL;
+	  grub_size_t oneshot_entry_size;
+	  status = grub_efi_get_variable("LoaderEntryOneShot",
+									 &grub_efi_loader_guid,
+									 &oneshot_entry_size,
+									 (void**) &oneshot_entry_efi);
+	  if (status == GRUB_EFI_SUCCESS)
+		{
+		  grub_efi_char16_t *src = oneshot_entry_efi;
+		  int size = 0;
+		  while (*src++)
+			size++;
+		  if (size == 0)
+			{
+			  oneshot_entry = grub_malloc (size * sizeof (char));
+			  grub_utf16_to_utf8 ((grub_uint8_t*) oneshot_entry,
+								  (grub_uint16_t*) oneshot_entry_efi, size);
+			  oneshot_entry_index = search_entry (menu, oneshot_entry);
+			  if (oneshot_entry_index != -1)
+				{
+				  default_entry = oneshot_entry_index;
+				  grub_efi_set_variable_to_string("LoaderEntryOneShot",
+						  						  &grub_efi_loader_guid, "", 0);
+				}
+			  grub_free(oneshot_entry);
+			}
+		  grub_free(oneshot_entry_efi);
+		}
+	}
+#endif
+
   workaround_snapshot_menu_default_entry (menu, "default", &default_entry);
 
   /* If DEFAULT_ENTRY is not within the menu entries, fall back to