MokManager: Stop using EFI_VARIABLE_APPEND_WRITE

When writing MokList with EFI_VARIABLE_APPEND_WRITE, some HP laptops
may just return EFI_SUCCESS without writing the content into the flash,
so we have no way to detect if MokList is updated or not. Now we always
read MokList first and write it back with the new content.

#105

Signed-off-by: Gary Lin <[email protected]>

MokManager.c

@@ -880,14 +880,9 @@ static EFI_STATUS write_db(CHAR16 * db_name, void *MokNew, UINTN MokNewSize)
 	UINTN old_size;
 	UINTN new_size;
 
-	efi_status = gRT->SetVariable(db_name, &SHIM_LOCK_GUID,
-				      EFI_VARIABLE_NON_VOLATILE |
-				      EFI_VARIABLE_BOOTSERVICE_ACCESS |
-				      EFI_VARIABLE_APPEND_WRITE,
-				      MokNewSize, MokNew);
-	if (!EFI_ERROR(efi_status) || efi_status != EFI_INVALID_PARAMETER) {
-		return efi_status;
-	}
+	/* Do not use EFI_VARIABLE_APPEND_WRITE due to faulty firmwares.
+	 * ref: https://github.com/rhboot/shim/issues/55
+	 *      https://github.com/rhboot/shim/issues/105 */
 
 	efi_status = get_variable_attr(db_name, (UINT8 **)&old_data, &old_size,
 				       SHIM_LOCK_GUID, &attributes);