From 254d5123a17f1c43393a7608dc537c671a4e0003 Mon Sep 17 00:00:00 2001
From: daxpedda <daxpedda@gmail.com>
Date: Fri, 6 Dec 2024 09:30:50 +0100
Subject: [PATCH] Don't create sub-array unless necessary

---
 src/backends/wasm_js.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/backends/wasm_js.rs b/src/backends/wasm_js.rs
index 8837dab5..d42e62db 100644
--- a/src/backends/wasm_js.rs
+++ b/src/backends/wasm_js.rs
@@ -29,7 +29,11 @@ pub fn fill_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
                 .expect("chunk length is bounded by CRYPTO_BUFFER_SIZE");
             // The chunk can be smaller than buf's length, so we call to
             // JS to create a smaller view of buf without allocation.
-            let sub_buf = buf.subarray(0, chunk_len);
+            let sub_buf = if chunk_len == u32::from(CRYPTO_BUFFER_SIZE) {
+                buf.clone()
+            } else {
+                buf.subarray(0, chunk_len)
+            };
 
             if crypto.get_random_values(&sub_buf).is_err() {
                 return Err(Error::WEB_GET_RANDOM_VALUES);