From 4c299bfca91c85bce73b7a17672050594d0b3d29 Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Thu, 14 Nov 2024 10:32:15 -0500
Subject: [PATCH] Better handle unexpected conditions when deserializing

For example, when deserialzing from corrupted storage.
---
 src/js/s14e-serializer.js | 36 ++++++++++++++++++++----------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/src/js/s14e-serializer.js b/src/js/s14e-serializer.js
index 98f0d9cc2..8b1850f13 100644
--- a/src/js/s14e-serializer.js
+++ b/src/js/s14e-serializer.js
@@ -1097,32 +1097,36 @@ export const serialize = (data, options = {}) => {
     return ratio <= 0.85 ? t : s;
 };
 
-export const deserialize = s => {
-    if ( s.startsWith(MAGICLZ4PREFIX) ) {
-        refCounter = 1;
-        readStr = s;
-        readEnd = s.length;
-        readPtr = MAGICLZ4PREFIX.length;
-        const lz4 = _deserialize();
-        readRefs.clear();
-        readStr = '';
-        const lz4Util = new LZ4BlockJS();
-        const uint8ArrayAfter = lz4Util.decode(lz4.data, 0, lz4.size);
-        s = textCodec.decode(new Uint8Array(uint8ArrayAfter));
-    }
-    if ( s.startsWith(MAGICPREFIX) === false ) { return; }
+const deserializeById = (blockid, s) => {
     refCounter = 1;
     readStr = s;
     readEnd = s.length;
-    readPtr = MAGICPREFIX.length;
+    readPtr = blockid.length;
     const data = _deserialize();
     readRefs.clear();
     readStr = '';
-    uint8Input = null;
     if ( readPtr === FAILMARK ) { return; }
     return data;
 };
 
+export const deserialize = s => {
+    if ( s.startsWith(MAGICLZ4PREFIX) ) {
+        const lz4 = deserializeById(MAGICLZ4PREFIX, s);
+        if ( lz4 ) {
+            const lz4Util = new LZ4BlockJS();
+            const uint8ArrayAfter = lz4Util.decode(lz4.data, 0, lz4.size);
+            if ( uint8ArrayAfter ) {
+                s = textCodec.decode(new Uint8Array(uint8ArrayAfter));
+            }
+        }
+    }
+    const data = s.startsWith(MAGICPREFIX)
+        ? deserializeById(MAGICPREFIX, s)
+        : undefined;
+    uint8Input = null;
+    return data;
+};
+
 export const isSerialized = s =>
     typeof s === 'string' &&
         (s.startsWith(MAGICLZ4PREFIX) || s.startsWith(MAGICPREFIX));