From 3a1864517efe402b71685b75ebb01436052b5983 Mon Sep 17 00:00:00 2001
From: Kris Zyp <kriszyp@gmail.com>
Date: Thu, 2 Jan 2025 12:38:49 -0700
Subject: [PATCH] Enforce safe access to the user shared array buffers

---
 read.js | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/read.js b/read.js
index 0587d5501..7148d50f4 100644
--- a/read.js
+++ b/read.js
@@ -401,17 +401,23 @@ export function addReadMethods(
 					keySize = this.writeKey(id, keyBytes, 4);
 				}
 			};
-			setKeyBytes();
-			let sharedBuffer = getUserSharedBuffer(
-				env.address,
-				keySize,
-				defaultBuffer,
-				options?.callback,
-			);
-			sharedBuffer.notify = () => {
+			let userSharedBuffers =
+				this._userSharedBuffers || (this._userSharedBuffers = new Map());
+			let sharedBuffer = userSharedBuffers.get(id.toString());
+			if (!sharedBuffer) {
 				setKeyBytes();
-				return notifyUserCallbacks(env.address, keySize);
-			};
+				sharedBuffer = getUserSharedBuffer(
+					env.address,
+					keySize,
+					defaultBuffer,
+					options?.callback,
+				);
+				userSharedBuffers.set(id.toString(), sharedBuffer);
+				sharedBuffer.notify = () => {
+					setKeyBytes();
+					return notifyUserCallbacks(env.address, keySize);
+				};
+			}
 			return sharedBuffer;
 		},