Add set_unencrypted_volume_mode to Storage

The new set_unencrypted_volume_mode method sets the access mode of the
unencrypted volume on the Nitrokey Storage.  Depending on the requested
access mode, it calls either NK_set_unencrypted_read_only_admin or
NK_set_unencrypted_read_write_admin.

Note that this function requires firmware version 0.51 or later.
(Earlier firmware versions used the user PIN.)

4 files changed, 81 insertions, 3 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b475168..b5f7b45 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,8 @@
   `CommandError::InvalidHexString` and `CommandError::TargetBufferTooSmall`.
 - Add the `get_library_version` function to query the libnitrokey version.
 - Add the `wink` method to the `Storage` struct.
+- Add the `set_unencrypted_volume_mode` to set the access mode of the
+  unencrypted volume.
 
 # v0.3.1 (2019-01-07)
 - Use `nitrokey-test` to select and execute the unit tests.
diff --git a/TODO.md b/TODO.md
index cd258fc..65ee4ea 100644
--- a/TODO.md
+++ b/TODO.md
@@ -3,9 +3,7 @@
     - `NK_is_AES_supported`
     - `NK_send_startup`
     - `NK_set_unencrypted_read_only`
-    - `NK_set_unencrypted_read_only_admin`
     - `NK_set_unencrypted_read_write`
-    - `NK_set_unencrypted_read_write_admin`
     - `NK_set_encrypted_read_only`
     - `NK_set_encrypted_read_write`
     - `NK_export_firmware`
diff --git a/src/device.rs b/src/device.rs
index 792ac2f..ee8e31c 100644
--- a/src/device.rs
+++ b/src/device.rs
@@ -1076,6 +1076,52 @@ impl Storage {
         }
     }
 
+    /// Sets the access mode of the unencrypted volume.
+    ///
+    /// This command will reconnect the unencrypted volume so buffers should be flushed before
+    /// calling it.  Since firmware version v0.51, this command requires the admin PIN.  Older
+    /// firmware versions are not supported.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if the provided password contains a null byte
+    /// - [`WrongPassword`][] if the provided admin password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::CommandError;
+    /// use nitrokey::VolumeMode;
+    ///
+    /// # fn try_main() -> Result<(), CommandError> {
+    /// let device = nitrokey::Storage::connect()?;
+    /// match device.set_unencrypted_volume_mode("123456", VolumeMode::ReadWrite) {
+    ///     Ok(()) => println!("Set the unencrypted volume to read-write mode."),
+    ///     Err(err) => println!("Could not set the unencrypted volume to read-write mode: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidString`]: enum.CommandError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    pub fn set_unencrypted_volume_mode(
+        &self,
+        admin_pin: &str,
+        mode: VolumeMode,
+    ) -> Result<(), CommandError> {
+        let admin_pin = get_cstring(admin_pin)?;
+        let result = match mode {
+            VolumeMode::ReadOnly => unsafe {
+                nitrokey_sys::NK_set_unencrypted_read_only_admin(admin_pin.as_ptr())
+            },
+            VolumeMode::ReadWrite => unsafe {
+                nitrokey_sys::NK_set_unencrypted_read_write_admin(admin_pin.as_ptr())
+            },
+        };
+        get_command_result(result)
+    }
+
     /// Returns the status of the connected storage device.
     ///
     /// # Example
diff --git a/tests/device.rs b/tests/device.rs
index 6f21dcb..9985e7a 100644
--- a/tests/device.rs
+++ b/tests/device.rs
@@ -6,7 +6,7 @@ use std::{thread, time};
 
 use nitrokey::{
     Authenticate, CommandError, Config, ConfigureOtp, Device, GenerateOtp, GetPasswordSafe,
-    OtpMode, OtpSlotData,
+    OtpMode, OtpSlotData, Storage, VolumeMode,
 };
 use nitrokey_test::test as test_device;
 
@@ -399,6 +399,38 @@ fn lock(device: Storage) {
 }
 
 #[test_device]
+fn set_unencrypted_volume_mode(device: Storage) {
+    fn assert_mode(device: &Storage, mode: VolumeMode) {
+        let status = device.get_status();
+        assert!(status.is_ok());
+        assert_eq!(
+            status.unwrap().unencrypted_volume.read_only,
+            mode == VolumeMode::ReadOnly
+        );
+    }
+
+    fn assert_success(device: &Storage, mode: VolumeMode) {
+        assert_eq!(
+            Ok(()),
+            device.set_unencrypted_volume_mode(ADMIN_PASSWORD, mode)
+        );
+        assert_mode(&device, mode);
+    }
+
+    assert_success(&device, VolumeMode::ReadOnly);
+
+    assert_eq!(
+        Err(CommandError::WrongPassword),
+        device.set_unencrypted_volume_mode(USER_PASSWORD, VolumeMode::ReadOnly)
+    );
+    assert_mode(&device, VolumeMode::ReadOnly);
+
+    assert_success(&device, VolumeMode::ReadWrite);
+    assert_success(&device, VolumeMode::ReadWrite);
+    assert_success(&device, VolumeMode::ReadOnly);
+}
+
+#[test_device]
 fn get_storage_status(device: Storage) {
     let status = device.get_status().unwrap();