Hash & gather factory deps to snapshot (#42)

Factory deps (smart contracts in zkSync) are stored separately in
snapshots, but they must be gathered together with storage log entries
when fetching the state from L1. This change will do preliminary work
required for writing out the separate factory dep snapshot file.

Cargo.toml

@@ -23,3 +23,4 @@ tokio = { version = "1.33.0", features = ["macros"] }
 tracing = "0.1.40"
 tracing-subscriber = "0.3.17"
 zksync_merkle_tree = { git = "https://github.com/matter-labs/zksync-era.git" }
+zkevm_opcode_defs = { git = "https://github.com/matter-labs/era-zkevm_opcode_defs.git" }

src/processor/snapshot/bytecode.rs

@@ -0,0 +1,26 @@
+use ethers::types::H256;
+
+// These are copied from zkSync-era project to avoid pulling in full dependency.
+pub fn bytes_to_chunks(bytes: &[u8]) -> Vec<[u8; 32]> {
+    assert!(
+        bytes.len() % 32 == 0,
+        "Bytes must be divisible by 32 to split into chunks"
+    );
+
+    bytes
+        .chunks(32)
+        .map(|el| {
+            let mut chunk = [0u8; 32];
+            chunk.copy_from_slice(el);
+            chunk
+        })
+        .collect()
+}
+
+pub fn hash_bytecode(code: &[u8]) -> H256 {
+    let chunked_code = bytes_to_chunks(code);
+    let hash =
+        zkevm_opcode_defs::utils::bytecode_to_code_hash(&chunked_code).expect("Invalid bytecode");
+
+    H256(hash)
+}

src/processor/snapshot/mod.rs

@@ -1,5 +1,6 @@
 use std::{collections::HashMap, fmt, fs, path::PathBuf, str::FromStr};
 
+mod bytecode;
 mod types;
 
 use async_trait::async_trait;
@@ -13,7 +14,7 @@ use state_reconstruct_fetcher::{
 };
 use tokio::sync::mpsc;
 
-use self::types::{SnapshotStorageLog, StorageKey, StorageValue};
+use self::types::{SnapshotFactoryDependency, SnapshotStorageLog, StorageKey, StorageValue};
 use super::Processor;
 use crate::processor::snapshot::types::MiniblockNumber;
 
@@ -22,6 +23,7 @@ const DEFAULT_EXPORT_PATH: &str = "snapshot_export";
 
 pub struct SnapshotExporter {
     storage_log_entries: HashMap<StorageKey, SnapshotStorageLog>,
+    factory_deps: Vec<SnapshotFactoryDependency>,
     index_to_key_map: IndexSet<U256>,
     path: PathBuf,
 }
@@ -45,6 +47,7 @@ impl SnapshotExporter {
 
         Self {
             storage_log_entries,
+            factory_deps: vec![],
             index_to_key_map,
             path,
         }
@@ -103,9 +106,13 @@ impl Processor for SnapshotExporter {
                     .and_modify(|log| log.value = value);
             }
 
-            // TODO: We need to index these by hash.
             // Factory dependencies.
-            // for dep in &block.factory_deps {}
+            for dep in block.factory_deps {
+                self.factory_deps.push(SnapshotFactoryDependency {
+                    bytecode_hash: bytecode::hash_bytecode(&dep),
+                    bytecode: dep,
+                });
+            }
         }
 
         fs::write(&self.path, self.to_string()).expect("failed to export snapshot");