From d75a5969eca9a83893af0b9324168e669547511d Mon Sep 17 00:00:00 2001
From: pinkiebell <40266861+pinkiebell@users.noreply.github.com>
Date: Wed, 30 Nov 2022 07:57:06 +0000
Subject: [PATCH 1/2] bus-mapping: fix return data offset and length
 bookkeeping

This resolves a problem with the returndatacopy opcode because
of zero return_data.[offset, length]
---
 .../src/circuit_input_builder/input_state_ref.rs       | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/bus-mapping/src/circuit_input_builder/input_state_ref.rs b/bus-mapping/src/circuit_input_builder/input_state_ref.rs
index 724e897290..6b05649204 100644
--- a/bus-mapping/src/circuit_input_builder/input_state_ref.rs
+++ b/bus-mapping/src/circuit_input_builder/input_state_ref.rs
@@ -808,7 +808,7 @@ impl<'a> CircuitInputStateRef<'a> {
     pub fn handle_return(&mut self, step: &GethExecStep) -> Result<(), Error> {
         // handle return_data
         if !self.call()?.is_root {
-            match step.op {
+            let (offset, length) = match step.op {
                 OpcodeId::RETURN | OpcodeId::REVERT => {
                     let offset = step.stack.nth_last(0)?.as_usize();
                     let length = step.stack.nth_last(1)?.as_usize();
@@ -821,12 +821,18 @@ impl<'a> CircuitInputStateRef<'a> {
                         caller_ctx.return_data[0..length]
                             .copy_from_slice(&callee_memory.0[offset..offset + length]);
                     }
+                    (offset, length)
                 }
                 _ => {
                     let caller_ctx = self.caller_ctx_mut()?;
                     caller_ctx.return_data.truncate(0);
+                    (0, 0)
                 }
-            }
+            };
+
+            let call = self.call_mut()?;
+            call.return_data_offset = offset.try_into().unwrap();
+            call.return_data_length = length.try_into().unwrap();
         }
 
         let call = self.call()?.clone();

From 6cd966d3895d28e19a35e9eccabd97c81f204def Mon Sep 17 00:00:00 2001
From: pinkiebell <40266861+pinkiebell@users.noreply.github.com>
Date: Wed, 30 Nov 2022 14:23:31 +0000
Subject: [PATCH 2/2] fix conflict

---
 .../circuit_input_builder/input_state_ref.rs  | 56 ++++++++++---------
 1 file changed, 29 insertions(+), 27 deletions(-)

diff --git a/bus-mapping/src/circuit_input_builder/input_state_ref.rs b/bus-mapping/src/circuit_input_builder/input_state_ref.rs
index 6b05649204..e6221bcdf6 100644
--- a/bus-mapping/src/circuit_input_builder/input_state_ref.rs
+++ b/bus-mapping/src/circuit_input_builder/input_state_ref.rs
@@ -807,33 +807,35 @@ impl<'a> CircuitInputStateRef<'a> {
     /// previous call context.
     pub fn handle_return(&mut self, step: &GethExecStep) -> Result<(), Error> {
         // handle return_data
-        if !self.call()?.is_root {
-            let (offset, length) = match step.op {
-                OpcodeId::RETURN | OpcodeId::REVERT => {
-                    let offset = step.stack.nth_last(0)?.as_usize();
-                    let length = step.stack.nth_last(1)?.as_usize();
-                    // TODO: Try to get rid of clone.
-                    // At the moment it conflicts with `call_ctx` and `caller_ctx`.
-                    let callee_memory = self.call_ctx()?.memory.clone();
-                    let caller_ctx = self.caller_ctx_mut()?;
-                    caller_ctx.return_data.resize(length, 0);
-                    if length != 0 {
-                        caller_ctx.return_data[0..length]
-                            .copy_from_slice(&callee_memory.0[offset..offset + length]);
+        let (return_data_offset, return_data_length) = {
+            if !self.call()?.is_root {
+                let (offset, length) = match step.op {
+                    OpcodeId::RETURN | OpcodeId::REVERT => {
+                        let offset = step.stack.nth_last(0)?.as_usize();
+                        let length = step.stack.nth_last(1)?.as_usize();
+                        // TODO: Try to get rid of clone.
+                        // At the moment it conflicts with `call_ctx` and `caller_ctx`.
+                        let callee_memory = self.call_ctx()?.memory.clone();
+                        let caller_ctx = self.caller_ctx_mut()?;
+                        caller_ctx.return_data.resize(length, 0);
+                        if length != 0 {
+                            caller_ctx.return_data[0..length]
+                                .copy_from_slice(&callee_memory.0[offset..offset + length]);
+                        }
+                        (offset, length)
                     }
-                    (offset, length)
-                }
-                _ => {
-                    let caller_ctx = self.caller_ctx_mut()?;
-                    caller_ctx.return_data.truncate(0);
-                    (0, 0)
-                }
-            };
+                    _ => {
+                        let caller_ctx = self.caller_ctx_mut()?;
+                        caller_ctx.return_data.truncate(0);
+                        (0, 0)
+                    }
+                };
 
-            let call = self.call_mut()?;
-            call.return_data_offset = offset.try_into().unwrap();
-            call.return_data_length = length.try_into().unwrap();
-        }
+                (offset.try_into().unwrap(), length.try_into().unwrap())
+            } else {
+                (0, 0)
+            }
+        };
 
         let call = self.call()?.clone();
         let call_ctx = self.call_ctx()?;
@@ -861,8 +863,8 @@ impl<'a> CircuitInputStateRef<'a> {
         // If current call has caller.
         if let Ok(caller) = self.caller_mut() {
             caller.last_callee_id = call.call_id;
-            caller.last_callee_return_data_length = call.return_data_length;
-            caller.last_callee_return_data_offset = call.return_data_offset;
+            caller.last_callee_return_data_length = return_data_length;
+            caller.last_callee_return_data_offset = return_data_offset;
         }
 
         self.tx_ctx.pop_call_ctx();