From 2b3b22f5594c4699ee238477d56aa98282ff3666 Mon Sep 17 00:00:00 2001
From: Riccardo Casatta <riccardo@casatta.it>
Date: Fri, 16 Jul 2021 15:05:15 +0200
Subject: [PATCH] impl Encodable for Annex to avoid allocation

---
 src/consensus/encode.rs |  2 +-
 src/util/sighash.rs     | 10 ++++++++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/consensus/encode.rs b/src/consensus/encode.rs
index cdf4496d..a796c60b 100644
--- a/src/consensus/encode.rs
+++ b/src/consensus/encode.rs
@@ -600,7 +600,7 @@ impl_vec!(u64);
 #[cfg(feature = "std")] impl_vec!((u32, Address));
 #[cfg(feature = "std")] impl_vec!(AddrV2Message);
 
-fn consensus_encode_with_size<S: io::Write>(data: &[u8], mut s: S) -> Result<usize, io::Error> {
+pub(crate) fn consensus_encode_with_size<S: io::Write>(data: &[u8], mut s: S) -> Result<usize, io::Error> {
     let vi_len = VarInt(data.len() as u64).consensus_encode(&mut s)?;
     s.emit_slice(&data)?;
     Ok(vi_len + data.len())
diff --git a/src/util/sighash.rs b/src/util/sighash.rs
index d049e37d..5557fa0a 100644
--- a/src/util/sighash.rs
+++ b/src/util/sighash.rs
@@ -20,7 +20,7 @@
 //!
 
 pub use blockdata::transaction::SigHashType as LegacySigHashType;
-use consensus::Encodable;
+use consensus::{encode, Encodable};
 use core::fmt;
 use core::ops::{Deref, DerefMut};
 use hashes::{sha256, sha256d, Hash};
@@ -344,7 +344,7 @@ impl<R: Deref<Target = Transaction>> SigHashCache<R> {
         //      includes the mandatory 0x50 prefix.
         if let Some(annex) = annex {
             let mut enc = sha256::Hash::engine();
-            annex.as_bytes().to_vec().consensus_encode(&mut enc)?;
+            annex.consensus_encode(&mut enc)?;
             let hash = sha256::Hash::from_engine(enc);
             hash.consensus_encode(&mut writer)?;
         }
@@ -626,6 +626,12 @@ impl<'a> Annex<'a> {
     }
 }
 
+impl<'a> Encodable for Annex<'a> {
+    fn consensus_encode<W: io::Write>(&self, writer: W) -> Result<usize, io::Error> {
+        encode::consensus_encode_with_size(&self.0, writer)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use consensus::deserialize;