From 7f72218a151b6196be0ad83008ddb80d499f34e4 Mon Sep 17 00:00:00 2001
From: skrrb <skrrb@pm.me>
Date: Wed, 7 Feb 2024 11:44:55 +0100
Subject: [PATCH] impl ZeroCopyDeserialize for jup

---
 lib/client/src/jup.rs  | 15 +++++++++------
 lib/client/src/util.rs | 17 ++++++++++++++++-
 2 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/lib/client/src/jup.rs b/lib/client/src/jup.rs
index 77d0b0ebf..83d67a60b 100644
--- a/lib/client/src/jup.rs
+++ b/lib/client/src/jup.rs
@@ -1,4 +1,3 @@
-use anchor_lang::AccountDeserialize;
 use anchor_lang::__private::bytemuck::Zeroable;
 use anchor_lang::prelude::*;
 use anchor_spl::token::Token;
@@ -14,6 +13,7 @@ use openbook_v2::{
 use crate::{
     book::{amounts_from_book, Amounts},
     remaining_accounts_to_crank,
+    util::ZeroCopyDeserialize,
 };
 use jupiter_amm_interface::{
     AccountMap, Amm, KeyedAccount, Quote, QuoteParams, Side as JupiterSide, Swap,
@@ -59,7 +59,8 @@ impl Amm for OpenBookMarket {
     }
 
     fn from_keyed_account(keyed_account: &KeyedAccount) -> Result<Self> {
-        let market = Market::try_deserialize(&mut keyed_account.account.data.as_slice())?;
+        let market =
+            Market::try_deserialize_from_slice(&mut keyed_account.account.data.as_slice())?;
         let mut related_accounts = vec![
             market.bids,
             market.asks,
@@ -91,13 +92,14 @@ impl Amm for OpenBookMarket {
 
     fn update(&mut self, account_map: &AccountMap) -> Result<()> {
         let bids_data = account_map.get(&self.market.bids).unwrap();
-        self.bids = BookSide::try_deserialize(&mut bids_data.data.as_slice()).unwrap();
+        self.bids = BookSide::try_deserialize_from_slice(&mut bids_data.data.as_slice()).unwrap();
 
         let asks_data = account_map.get(&self.market.asks).unwrap();
-        self.asks = BookSide::try_deserialize(&mut asks_data.data.as_slice()).unwrap();
+        self.asks = BookSide::try_deserialize_from_slice(&mut asks_data.data.as_slice()).unwrap();
 
         let event_heap_data = account_map.get(&self.market.event_heap).unwrap();
-        self.event_heap = EventHeap::try_deserialize(&mut event_heap_data.data.as_slice()).unwrap();
+        self.event_heap =
+            EventHeap::try_deserialize_from_slice(&mut event_heap_data.data.as_slice()).unwrap();
 
         let clock_data = account_map.get(&clock::ID).unwrap();
         let clock: Clock = bincode::deserialize(clock_data.data.as_slice())?;
@@ -401,7 +403,8 @@ mod test {
             let user_input_account = Pubkey::new_unique();
             let user_output_account = Pubkey::new_unique();
 
-            let market_data = Market::try_deserialize(&mut market_account.account.data.as_slice())?;
+            let market_data =
+                Market::try_deserialize_from_slice(&mut market_account.account.data.as_slice())?;
 
             add_token_account(user_input_account, user.pubkey(), input_mint);
             add_token_account(user_output_account, user.pubkey(), output_mint);
diff --git a/lib/client/src/util.rs b/lib/client/src/util.rs
index 02d0e9177..fd771debb 100644
--- a/lib/client/src/util.rs
+++ b/lib/client/src/util.rs
@@ -1,3 +1,4 @@
+use anchor_lang::{error::Error, AccountDeserialize, ZeroCopy};
 use solana_client::{
     client_error::Result as ClientResult, rpc_client::RpcClient, rpc_request::RpcError,
 };
@@ -6,9 +7,23 @@ use solana_sdk::{
     clock::Slot, commitment_config::CommitmentConfig, signature::Signature,
     transaction::uses_durable_nonce,
 };
-
 use std::{thread, time};
 
+/// zero copy accounts could be larger than the underlying struct
+/// https://github.com/coral-xyz/anchor/blob/08110e63fa5a7369830db972d4abdcfa1aaa7f2e/lang/src/accounts/account_loader.rs#L165
+/// https://github.com/coral-xyz/anchor/blob/08110e63fa5a7369830db972d4abdcfa1aaa7f2e/lang/attribute/account/src/lib.rs#L195
+pub trait ZeroCopyDeserialize {
+    fn try_deserialize_from_slice(buf: &mut &[u8]) -> Result<Self, Error>
+    where
+        Self: Sized;
+}
+
+impl<T: AccountDeserialize + ZeroCopy> ZeroCopyDeserialize for T {
+    fn try_deserialize_from_slice(buf: &mut &[u8]) -> Result<Self, Error> {
+        Self::try_deserialize(&mut &buf[..std::mem::size_of::<Self>() + 8])
+    }
+}
+
 /// Some Result<> types don't convert to anyhow::Result nicely. Force them through stringification.
 pub trait AnyhowWrap {
     type Value;