turn FormattableErrorResponse into an actual Error type

By removing the NoError variant as it is useless.

src/lib.rs

@@ -133,11 +133,10 @@ impl<'a> RefreshableOathCredential<'a> {
 }
 
 impl<'a> OathSession<'a> {
-    pub fn new(name: &str) -> Result<Self, FormattableErrorResponse> {
+    pub fn new(name: &str) -> Result<Self, Error> {
         let transaction_context = TransactionContext::from_name(name)?;
-        let info_buffer = transaction_context
-            .apdu_read_all(0, INS_SELECT, 0x04, 0, Some(&OATH_AID))
-            .unwrap();
+        let info_buffer =
+            transaction_context.apdu_read_all(0, INS_SELECT, 0x04, 0, Some(&OATH_AID))?;
 
         let info_map = tlv_to_map(info_buffer);
         for (tag, data) in &info_map {
@@ -167,10 +166,7 @@ impl<'a> OathSession<'a> {
         self.version
     }
 
-    pub fn delete_code(
-        &self,
-        cred: OathCredential,
-    ) -> Result<ApduResponse, FormattableErrorResponse> {
+    pub fn delete_code(&self, cred: OathCredential) -> Result<ApduResponse, Error> {
         self.transaction_context.apdu(
             0,
             Instruction::Delete as u8,
@@ -184,9 +180,9 @@ impl<'a> OathSession<'a> {
         &self,
         cred: OathCredential,
         timestamp_sys: Option<SystemTime>,
-    ) -> Result<OathCodeDisplay, FormattableErrorResponse> {
+    ) -> Result<OathCodeDisplay, Error> {
         if self.name != cred.device_id {
-            return Err(FormattableErrorResponse::DeviceMismatchError);
+            return Err(Error::DeviceMismatchError);
         }
 
         let timestamp = time_to_u64(timestamp_sys.unwrap_or_else(SystemTime::now));
@@ -207,23 +203,18 @@ impl<'a> OathSession<'a> {
             Some(&data),
         );
 
-        let meta =
-            TlvIter::from_vec(resp?)
-                .next()
-                .ok_or(FormattableErrorResponse::ParsingError(
+        let meta = TlvIter::from_vec(resp?).next().ok_or(Error::ParsingError(
             "No credentials to unpack found in response".to_string(),
         ))?;
 
-        OathCodeDisplay::from_tlv(meta).ok_or(FormattableErrorResponse::ParsingError(
+        OathCodeDisplay::from_tlv(meta).ok_or(Error::ParsingError(
             "error parsing calculation response".to_string(),
         ))
     }
 
     /// Read the OATH codes from the device, calculate TOTP codes that don't
     /// need touch
-    pub fn calculate_oath_codes(
-        &self,
-    ) -> Result<Vec<RefreshableOathCredential>, FormattableErrorResponse> {
+    pub fn calculate_oath_codes(&self) -> Result<Vec<RefreshableOathCredential>, Error> {
         let timestamp = SystemTime::now();
         // Request OATH codes from device
         let response = self.transaction_context.apdu_read_all(
@@ -258,7 +249,7 @@ impl<'a> OathSession<'a> {
 
         return Ok(key_buffer);
     }
-    pub fn list_oath_codes(&self) -> Result<Vec<CredentialIDData>, FormattableErrorResponse> {
+    pub fn list_oath_codes(&self) -> Result<Vec<CredentialIDData>, Error> {
         // Request OATH codes from device
         let response =
             self.transaction_context

src/transaction.rs

@@ -8,8 +8,7 @@ use pcsc::{Card, Transaction};
 use crate::{ErrorResponse, Instruction, SuccessResponse, Tag};
 
 #[derive(PartialEq, Eq, Debug)]
-pub enum FormattableErrorResponse {
-    NoError,
+pub enum Error {
     Unknown(String),
     Protocol(ErrorResponse),
     PcscError(pcsc::Error),
@@ -17,46 +16,31 @@ pub enum FormattableErrorResponse {
     DeviceMismatchError,
 }
 
-impl FormattableErrorResponse {
-    pub fn from_apdu_response(sw1: u8, sw2: u8) -> Self {
+impl Error {
+    fn from_apdu_response(sw1: u8, sw2: u8) -> Result<(), Self> {
         let code: u16 = (sw1 as u16 | sw2 as u16) << 8;
         if let Some(e) = ErrorResponse::any_match(code) {
-            return Self::Protocol(e);
+            return Err(Self::Protocol(e));
         }
         if SuccessResponse::any_match(code)
             .or(SuccessResponse::any_match(sw1.into()))
             .is_some()
         {
-            return Self::NoError;
+            return Ok(());
         }
-        Self::Unknown(String::from("Unknown error"))
-    }
-    pub fn is_ok(&self) -> bool {
-        *self == Self::NoError
-    }
-    pub fn as_opt(self) -> Option<Self> {
-        if self.is_ok() {
-            None
-        } else {
-            Some(self)
-        }
-    }
-
-    fn from_transmit(err: pcsc::Error) -> Self {
-        Self::PcscError(err)
+        Err(Self::Unknown(String::from("Unknown error")))
     }
 }
 
-impl From<pcsc::Error> for FormattableErrorResponse {
+impl From<pcsc::Error> for Error {
     fn from(value: pcsc::Error) -> Self {
         Self::PcscError(value)
     }
 }
 
-impl Display for FormattableErrorResponse {
+impl Display for Error {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            Self::NoError => f.write_str("ok"),
             Self::Unknown(msg) => f.write_str(msg),
             Self::Protocol(error_response) => f.write_fmt(format_args!("{}", error_response)),
             Self::PcscError(error) => f.write_fmt(format_args!("{}", error)),
@@ -80,7 +64,7 @@ fn apdu(
     parameter1: u8,
     parameter2: u8,
     data: Option<&[u8]>,
-) -> Result<ApduResponse, FormattableErrorResponse> {
+) -> Result<ApduResponse, Error> {
     let command = if let Some(data) = data {
         Command::new_with_payload(class, instruction, parameter1, parameter2, data)
     } else {
@@ -93,19 +77,9 @@ fn apdu(
     let mut rx_buf = [0; pcsc::MAX_BUFFER_SIZE];
 
     // Write the payload to the device and error if there is a problem
-    let rx_buf = match tx.transmit(&tx_buf, &mut rx_buf) {
-        Ok(slice) => slice,
-        // Err(err) => return Err(format!("{}", err)),
-        Err(err) => return Err(FormattableErrorResponse::from_transmit(err)),
-    };
-
+    let rx_buf = tx.transmit(&tx_buf, &mut rx_buf)?;
     let resp = Response::from(rx_buf);
-    let error_context =
-        FormattableErrorResponse::from_apdu_response(resp.trailer.0, resp.trailer.1);
-
-    if !error_context.is_ok() {
-        return Err(error_context);
-    }
+    Error::from_apdu_response(resp.trailer.0, resp.trailer.1)?;
 
     Ok(ApduResponse {
         buf: resp.payload.to_vec(),
@@ -121,7 +95,7 @@ fn apdu_read_all(
     parameter1: u8,
     parameter2: u8,
     data: Option<&[u8]>,
-) -> Result<Vec<u8>, FormattableErrorResponse> {
+) -> Result<Vec<u8>, Error> {
     let mut response_buf = Vec::new();
     let mut resp = apdu(tx, class, instruction, parameter1, parameter2, data)?;
     response_buf.extend(resp.buf);
@@ -141,7 +115,7 @@ pub struct TransactionContext {
 }
 
 impl TransactionContext {
-    pub fn from_name(name: &str) -> Result<Self, FormattableErrorResponse> {
+    pub fn from_name(name: &str) -> Result<Self, Error> {
         // Establish a PC/SC context
         let ctx = pcsc::Context::establish(pcsc::Scope::User)?;
 
@@ -166,7 +140,7 @@ impl TransactionContext {
         parameter1: u8,
         parameter2: u8,
         data: Option<&[u8]>,
-    ) -> Result<ApduResponse, FormattableErrorResponse> {
+    ) -> Result<ApduResponse, Error> {
         apdu(
             self.borrow_transaction(),
             class,
@@ -184,7 +158,7 @@ impl TransactionContext {
         parameter1: u8,
         parameter2: u8,
         data: Option<&[u8]>,
-    ) -> Result<Vec<u8>, FormattableErrorResponse> {
+    ) -> Result<Vec<u8>, Error> {
         apdu_read_all(
             self.borrow_transaction(),
             class,