Fixed error management in ui_display_tx

src/app_ui/sign.rs

@@ -19,56 +19,62 @@ use core::str::from_utf8;
 
 use crate::handlers::sign_tx::Tx;
 use crate::utils::concatenate;
+use crate::AppSW;
 use ledger_device_ui_sdk::bitmaps::{CROSSMARK, EYE, VALIDATE_14};
 use ledger_device_ui_sdk::ui::{Field, MultiFieldReview};
 use numtoa::NumToA;
 
 const MAX_COIN_LENGTH: usize = 10;
 
-pub fn ui_display_tx(tx: &Tx) -> bool {
+/// Displays a transaction and returns true if user approved it.
+///
+/// This method can return [`AppSW::TxDisplayFail`] error if the coin name length is too long.
+///
+/// # Arguments
+///
+/// * `tx` - Transaction to be displayed for validation
+pub fn ui_display_tx(tx: &Tx) -> Result<bool, AppSW> {
     // Generate string for amount
     let mut numtoa_buf = [0u8; 20];
     let mut value_buf = [0u8; 20 + MAX_COIN_LENGTH + 1];
 
-    if let Ok(value_str) = concatenate(
+    let value_str = concatenate(
         &[tx.coin, &" ", tx.value.numtoa_str(10, &mut numtoa_buf)],
         &mut value_buf,
-    ) {
-        // Generate destination address string in hexadecimal format.
-        let mut to_str = [0u8; 42];
-        to_str[..2].copy_from_slice("0x".as_bytes());
-        hex::encode_to_slice(tx.to, &mut to_str[2..]).unwrap();
+    )
+    .map_err(|_| AppSW::TxDisplayFail)?; // Fails if value_buf is too small
 
-        // Define transaction review fields
-        let my_fields = [
-            Field {
-                name: "Amount",
-                value: value_str,
-            },
-            Field {
-                name: "Destination",
-                value: core::str::from_utf8(&to_str).unwrap(),
-            },
-            Field {
-                name: "Memo",
-                value: tx.memo,
-            },
-        ];
+    // Generate destination address string in hexadecimal format.
+    let mut to_str = [0u8; 42];
+    to_str[..2].copy_from_slice("0x".as_bytes());
+    hex::encode_to_slice(tx.to, &mut to_str[2..]).unwrap();
 
-        // Create transaction review
-        let my_review = MultiFieldReview::new(
-            &my_fields,
-            &["Review ", "Transaction"],
-            Some(&EYE),
-            "Approve",
-            Some(&VALIDATE_14),
-            "Reject",
-            Some(&CROSSMARK),
-        );
+    // Define transaction review fields
+    let my_fields = [
+        Field {
+            name: "Amount",
+            value: value_str,
+        },
+        Field {
+            name: "Destination",
+            value: core::str::from_utf8(&to_str).unwrap(),
+        },
+        Field {
+            name: "Memo",
+            value: tx.memo,
+        },
+    ];
 
-        my_review.show()
-    } else {
-        // Coin name too long, concatenation buffer was too small.
-        return false;
-    }
+    // Create transaction review
+    let my_review = MultiFieldReview::new(
+        &my_fields,
+        &["Review ", "Transaction"],
+        Some(&EYE),
+        "Approve",
+        Some(&VALIDATE_14),
+        "Reject",
+        Some(&CROSSMARK),
+    );
+
+    Ok(my_review.show())
 }

src/handlers/sign_tx.rs

@@ -103,7 +103,7 @@ pub fn handler_sign_tx(
             // Display transaction. If user approves
             // the transaction, sign it. Otherwise,
             // return a "deny" status word.
-            if ui_display_tx(&tx) {
+            if ui_display_tx(&tx)? {
                 return compute_signature_and_append(comm, ctx);
             } else {
                 return Err(AppSW::Deny);