Represent serial numbers using SerialNumber struct

In a previous commit, we changed the serial number representation from a
string to an integer.  This made it easier to compare serial numbers,
but also introduced new problems:
- Serial numbers should be formatted consistently, for example as
  "{:#010x}".  It is hard to ensure this for an integer value.
- The format of the serial number may be subject to change.  Users
  should not rely too much on the u32 representation.

Therefore we introduce a new SerialNumber struct that represents a
serial number.  Currently it only stores a u32 value.  The following
traits and functions can be used to access its value:
- FromStr for string parsing
- ToString/Display for string formatting
- as_u32 to access the underlying integer value

1 files changed, 2 insertions, 2 deletions

diff --git a/src/device/storage.rs b/src/device/storage.rs
index 1e2c46d..5669a91 100644
--- a/src/device/storage.rs
+++ b/src/device/storage.rs
@@ -7,7 +7,7 @@ use std::ops;
 
 use nitrokey_sys;
 
-use crate::device::{Device, FirmwareVersion, Model, Status};
+use crate::device::{Device, FirmwareVersion, Model, SerialNumber, Status};
 use crate::error::{CommandError, Error};
 use crate::otp::GenerateOtp;
 use crate::util::{get_command_result, get_cstring, get_last_error};
@@ -827,7 +827,7 @@ impl<'a> Device<'a> for Storage<'a> {
 
         let storage_status = self.get_storage_status()?;
         status.firmware_version = storage_status.firmware_version;
-        status.serial_number = storage_status.serial_number_smart_card;
+        status.serial_number = SerialNumber::new(storage_status.serial_number_smart_card);
 
         Ok(status)
     }