Add list_devices function

This patch adds support for libnitrokey’s NK_list_devices function by
introducing the top-level list_devices function.  It returns a vector of
DeviceInfo structs with information about all connected Nitrokey
devices.

1 files changed, 68 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
index dad4a20..5600d24 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -109,8 +109,10 @@ mod otp;
 mod pws;
 mod util;
 
+use std::convert::TryInto as _;
 use std::fmt;
 use std::marker;
+use std::ptr::NonNull;
 use std::sync;
 
 use nitrokey_sys;
@@ -126,6 +128,8 @@ pub use crate::otp::{ConfigureOtp, GenerateOtp, OtpMode, OtpSlotData};
 pub use crate::pws::{GetPasswordSafe, PasswordSafe, SLOT_COUNT};
 pub use crate::util::LogLevel;
 
+use crate::util::get_last_result;
+
 /// The default admin PIN for all Nitrokey devices.
 pub const DEFAULT_ADMIN_PIN: &str = "12345678";
 /// The default user PIN for all Nitrokey devices.
@@ -416,6 +420,70 @@ pub fn force_take() -> Result<sync::MutexGuard<'static, Manager>, Error> {
     }
 }
 
+/// List all connected Nitrokey devices.
+///
+/// This functions returns a vector with [`DeviceInfo`][] structs that contain information about
+/// all connected Nitrokey devices.  It will even list unsupported models, although you cannot
+/// connect to them.
+///
+/// # Errors
+///
+/// - [`NotConnected`][] if a Nitrokey device has been disconnected during enumeration
+/// - [`Utf8Error`][] if the USB path or the serial number returned by libnitrokey are invalid
+///   UTF-8 strings
+///
+/// # Example
+///
+/// ```
+/// let devices = nitrokey::list_devices()?;
+/// if devices.is_empty() {
+///     println!("No connected Nitrokey devices found.");
+/// } else {
+///     println!("model\tpath\tserial number");
+///     for device in devices {
+///         match device.model {
+///             Some(model) => print!("{}", model),
+///             None => print!("unsupported"),
+///         }
+///         print!("\t{}\t", device.path);
+///         match device.serial_number {
+///             Some(serial_number) => println!("{}", serial_number),
+///             None => println!("unknown"),
+///         }
+///     }
+/// }
+/// # Ok::<(), nitrokey::Error>(())
+/// ```
+///
+/// [`DeviceInfo`]: struct.DeviceInfo.html
+/// [`NotConnected`]: enum.CommunicationError.html#variant.NotConnected
+/// [`Utf8Error`]: enum.Error.html#variant.Utf8Error
+pub fn list_devices() -> Result<Vec<DeviceInfo>, Error> {
+    let ptr = NonNull::new(unsafe { nitrokey_sys::NK_list_devices() });
+    match ptr {
+        Some(mut ptr) => {
+            let mut vec: Vec<DeviceInfo> = Vec::new();
+            push_device_info(&mut vec, unsafe { ptr.as_ref() })?;
+            unsafe {
+                nitrokey_sys::NK_free_device_info(ptr.as_mut());
+            }
+            Ok(vec)
+        }
+        None => get_last_result().map(|_| Vec::new()),
+    }
+}
+
+fn push_device_info(
+    vec: &mut Vec<DeviceInfo>,
+    info: &nitrokey_sys::NK_device_info,
+) -> Result<(), Error> {
+    vec.push(info.try_into()?);
+    if let Some(ptr) = NonNull::new(info.next) {
+        push_device_info(vec, unsafe { ptr.as_ref() })?;
+    }
+    Ok(())
+}
+
 /// Enables or disables debug output.  Calling this method with `true` is equivalent to setting the
 /// log level to `Debug`; calling it with `false` is equivalent to the log level `Error` (see
 /// [`set_log_level`][]).