fix: greatly simplify rusb usage

ledger/Cargo.toml

@@ -20,16 +20,12 @@ crate-type = ["cdylib", "rlib"]
 async-trait = "0.1"
 cfg-if = "1.0"
 hex = "0.4"
-serde = { version = "1.0", features = ["derive"] }
-tap = "1.0"
 thiserror = "1.0"
 
 # native
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
-lazy_static = "1.4"
+once_cell = "1.18.0"
 byteorder = "1.5"
-libc = "0.2"
-matches = "0.1"
 tracing = "0.1"
 hidapi-rusb = "1.3"
 tokio = { version = "1.34", features = ["sync", "rt"] }

ledger/src/common.rs

@@ -32,6 +32,7 @@ impl APDUData {
     }
 
     /// Consume the struct and get the underlying data
+    #[allow(clippy::missing_const_for_fn)] // false positive
     pub fn data(self) -> Vec<u8> {
         self.0
     }
@@ -234,12 +235,12 @@ impl std::fmt::Display for APDUResponseCodes {
 
 impl APDUResponseCodes {
     /// True if the response is a success, else false.
-    pub fn is_success(self) -> bool {
-        self == APDUResponseCodes::NoError
+    pub const fn is_success(self) -> bool {
+        matches!(self, APDUResponseCodes::NoError)
     }
 
     /// Return a description of the response code.
-    pub fn description(self) -> &'static str {
+    pub const fn description(self) -> &'static str {
         match self {
             APDUResponseCodes::NoError => "[APDU_CODE_NOERROR]",
             APDUResponseCodes::ExecutionError => {
@@ -265,7 +266,7 @@ impl APDUResponseCodes {
             }
             APDUResponseCodes::InvalidP1P2 => "[APDU_CODE_INVALIDP1P2] Wrong parameter(s) P1-P2",
             APDUResponseCodes::InsNotSupported => {
-                "[APDU_CODE_INS_NOT_SUPPORTED] Instruction code not supported or invalid"
+                "[APDU_CODE_INS_NOT_SUPPORTED] Instruction code not supported or invalid. Hint: Is the correct application open on the device?"
             }
             APDUResponseCodes::ClaNotSupported => {
                 "[APDU_CODE_CLA_NOT_SUPPORTED] Class not supported"

ledger/src/lib.rs

@@ -1,7 +1,16 @@
 //! Ledger utilites and transports
 
-#![warn(missing_docs)]
-#![warn(unused_extern_crates)]
+#![warn(
+    missing_copy_implementations,
+    missing_debug_implementations,
+    missing_docs,
+    unreachable_pub,
+    clippy::missing_const_for_fn,
+    rustdoc::all
+)]
+#![deny(unused_must_use, rust_2018_idioms)]
+#![cfg_attr(not(test), warn(unused_crate_dependencies))]
+#![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
 
 /// APDU utilities.
 pub mod common;
@@ -19,3 +28,4 @@ pub use {
 };
 
 mod protocol;
+pub use protocol::LedgerProtocol;

ledger/src/protocol.rs

@@ -9,6 +9,7 @@ use crate::{Ledger, LedgerError};
 /// be invoked. The protocol may also fail to recover, in which case future
 /// uses of the device may fail.
 pub trait LedgerProtocol {
+    /// The output of the protocol.
     type Output;
 
     /// Run the protocol. This sends commands to the device, and receives
@@ -29,6 +30,8 @@ pub trait LedgerProtocol {
         Ok(())
     }
 
+    /// Run the protocol. This sends commands to the device, and receives
+    /// responses. The transport is locked while this function is running.
     fn run(&mut self, transport: &mut Ledger) -> Result<Self::Output, LedgerError> {
         match self.execute(transport) {
             Ok(output) => Ok(output),

ledger/src/transports/mod.rs

@@ -27,6 +27,7 @@ cfg_if::cfg_if! {
 /// A Ledger device connection. This wraps the default transport type. In
 /// native code, this is the `hidapi` library. When the `node` or `browser`
 /// feature is selected, it is a Ledger JS transport library.
+#[derive(Debug)]
 pub struct Ledger(DefaultTransport);
 
 #[cfg_attr(not(target_arch = "wasm32"), async_trait)]

ledger/src/transports/native/error.rs

@@ -0,0 +1,50 @@
+use thiserror::Error;
+
+// Mock the type in other target_os
+#[cfg(not(target_os = "linux"))]
+mod nix {
+    #[derive(thiserror::Error, Debug, Copy, Clone)]
+    pub enum Error {
+        #[error("")]
+        Unimplemented,
+    }
+}
+
+/// Ledger transport errors
+#[derive(Error, Debug)]
+pub enum NativeTransportError {
+    /// Device not found error
+    #[error("Ledger device not found")]
+    DeviceNotFound,
+    /// Device open error.
+    #[error("Error opening device. {0}. Hint: This usually means that the device is already in use by another transport instance.")]
+    CantOpen(hidapi_rusb::HidError),
+    /// SequenceMismatch
+    #[error("Sequence mismatch. Got {got} from device. Expected {expected}")]
+    SequenceMismatch {
+        /// The sequence returned by the device
+        got: u16,
+        /// The expected sequence
+        expected: u16,
+    },
+    /// Communication error
+    #[error("Ledger device: communication error `{0}`")]
+    Comm(&'static str),
+    /// Ioctl error
+    #[error(transparent)]
+    Ioctl(#[from] nix::Error),
+    /// i/o error
+    #[error(transparent)]
+    Io(#[from] std::io::Error),
+    /// HID error
+    #[error(transparent)]
+    Hid(#[from] hidapi_rusb::HidError),
+    /// UT8F error
+    #[error(transparent)]
+    UTF8(#[from] std::str::Utf8Error),
+    /// Termux USB FD env var does not exist or fails to parse. This error is
+    /// only returned by android-specific code paths, and may be safely ignored
+    /// by non-android users
+    #[error("Invalid TERMUX_USB_FD variable. Are you using termux-usb?")]
+    InvalidTermuxUsbFd,
+}