From c69c3eafe73c6cb0a55809c6c0b819c055b195f9 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Tue, 28 Sep 2021 14:22:21 +1000
Subject: [PATCH] Partially implement --terminal-block-hash-override

---
 beacon_node/client/src/builder.rs |  4 ++++
 beacon_node/client/src/config.rs  |  4 +++-
 beacon_node/src/cli.rs            | 15 +++++++++++++--
 beacon_node/src/config.rs         |  2 ++
 4 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/beacon_node/client/src/builder.rs b/beacon_node/client/src/builder.rs
index 0079d3ec59..c3498397c9 100644
--- a/beacon_node/client/src/builder.rs
+++ b/beacon_node/client/src/builder.rs
@@ -150,12 +150,16 @@ where
         let terminal_total_difficulty = config
             .terminal_total_difficulty_override
             .unwrap_or(spec.terminal_total_difficulty);
+        let terminal_block_hash = config
+            .terminal_block_hash
+            .unwrap_or(spec.terminal_block_hash);
 
         let execution_layer = if let Some(execution_endpoints) = config.execution_endpoints {
             let context = runtime_context.service_context("exec".into());
             let execution_layer = ExecutionLayer::from_urls(
                 execution_endpoints,
                 terminal_total_difficulty,
+                terminal_block_hash,
                 config.fee_recipient,
                 context.executor.clone(),
                 context.log().clone(),
diff --git a/beacon_node/client/src/config.rs b/beacon_node/client/src/config.rs
index f950d3922d..d1fb4bd98a 100644
--- a/beacon_node/client/src/config.rs
+++ b/beacon_node/client/src/config.rs
@@ -4,7 +4,7 @@ use sensitive_url::SensitiveUrl;
 use serde_derive::{Deserialize, Serialize};
 use std::fs;
 use std::path::PathBuf;
-use types::{Address, Graffiti, PublicKeyBytes, Uint256};
+use types::{Address, Graffiti, Hash256, PublicKeyBytes, Uint256};
 
 /// Default directory name for the freezer database under the top-level data dir.
 const DEFAULT_FREEZER_DB_DIR: &str = "freezer_db";
@@ -76,6 +76,7 @@ pub struct Config {
     pub eth1: eth1::Config,
     pub execution_endpoints: Option<Vec<SensitiveUrl>>,
     pub terminal_total_difficulty_override: Option<Uint256>,
+    pub terminal_block_hash: Option<Hash256>,
     pub fee_recipient: Option<Address>,
     pub http_api: http_api::Config,
     pub http_metrics: http_metrics::Config,
@@ -99,6 +100,7 @@ impl Default for Config {
             eth1: <_>::default(),
             execution_endpoints: None,
             terminal_total_difficulty_override: None,
+            terminal_block_hash: None,
             fee_recipient: None,
             disabled_forks: Vec::new(),
             graffiti: Graffiti::default(),
diff --git a/beacon_node/src/cli.rs b/beacon_node/src/cli.rs
index e130518106..24edfdf2c4 100644
--- a/beacon_node/src/cli.rs
+++ b/beacon_node/src/cli.rs
@@ -376,8 +376,19 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                 .help("Used to coordinate manual overrides to the TERMINAL_TOTAL_DIFFICULTY parameter. \
                        This flag should only be used if the user has a clear understanding that \
                        the broad Ethereum community has elected to override the terminal difficulty. \
-                       Failure to do so will cause your node to experience a consensus failure. \
-                       Be extremely careful with the use of this flag.")
+                       Incorrect use of this flag will cause your node to experience a consensus
+                       failure. Be extremely careful with this flag.")
+                .takes_value(true)
+        )
+        .arg(
+            Arg::with_name("terminal-block-hash-override")
+                .long("terminal-block-hash-override")
+                .value_name("TERMINAL_BLOCK_HASH")
+                .help("Used to coordinate manual overrides to the TERMINAL_BLOCK_HASH parameter. \
+                       This flag should only be used if the user has a clear understanding that \
+                       the broad Ethereum community has elected to override the terminal PoW block. \
+                       Incorrect use of this flag will cause your node to experience a consensus
+                       failure. Be extremely careful with this flag.")
                 .takes_value(true)
         )
         .arg(
diff --git a/beacon_node/src/config.rs b/beacon_node/src/config.rs
index ea0a0ba148..96dbaf8cc9 100644
--- a/beacon_node/src/config.rs
+++ b/beacon_node/src/config.rs
@@ -238,6 +238,8 @@ pub fn get_config<E: EthSpec>(
     }
 
     client_config.fee_recipient = clap_utils::parse_optional(cli_args, "fee-recipient")?;
+    client_config.terminal_block_hash =
+        clap_utils::parse_optional(cli_args, "terminal-block-hash")?;
 
     if let Some(freezer_dir) = cli_args.value_of("freezer-dir") {
         client_config.freezer_db_path = Some(PathBuf::from(freezer_dir));