From ba7d3c41bf1f5531990850b31d00fb7026fc1b69 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Mon, 28 Mar 2022 19:46:47 +0000
Subject: [PATCH] rust: Improve `PrecomputedTransactionData` construction
 errors

We now log separate errors for "provided inputs when signing a coinbase
transaction" and "provided the wrong number of inputs to a transaction".
---
 src/rust/src/transaction_ffi.rs | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/src/rust/src/transaction_ffi.rs b/src/rust/src/transaction_ffi.rs
index 29bb48c20..517567a73 100644
--- a/src/rust/src/transaction_ffi.rs
+++ b/src/rust/src/transaction_ffi.rs
@@ -207,21 +207,32 @@ pub extern "C" fn zcash_transaction_precomputed_init(
                     return ptr::null_mut();
                 }
                 Ok(all_prev_outputs)
-                    if !tx
+                    if tx.transparent_bundle().map_or(false, |t| {
+                        // Coinbase txs have one fake input.
+                        t.is_coinbase() && !all_prev_outputs.is_empty()
+                    }) =>
+                {
+                    error!(
+                        "all_prev_outputs should be empty for a coinbase tx but has length {}",
+                        all_prev_outputs.len()
+                    );
+                    return ptr::null_mut();
+                }
+                Ok(all_prev_outputs)
+                    if tx
                         .transparent_bundle()
                         .map(|t| {
-                            if t.is_coinbase() {
-                                // Coinbase txs have one fake input.
-                                all_prev_outputs.is_empty()
-                            } else {
-                                // For non-coinbase txs, every input is real.
-                                t.vin.len() == all_prev_outputs.len()
-                            }
+                            // For non-coinbase txs, every input is real.
+                            !t.is_coinbase() && t.vin.len() != all_prev_outputs.len()
                         })
                         // If we have no transparent part, we should have no prev outputs.
-                        .unwrap_or_else(|| all_prev_outputs.is_empty()) =>
+                        .unwrap_or_else(|| !all_prev_outputs.is_empty()) =>
                 {
-                    error!("all_prev_outputs is incorrect length");
+                    error!(
+                        "all_prev_outputs is incorrect length {} (should be {})",
+                        all_prev_outputs.len(),
+                        tx.transparent_bundle().map(|t| t.vin.len()).unwrap_or(0),
+                    );
                     return ptr::null_mut();
                 }
                 Ok(all_prev_outputs) => MapTransparent {