From 54464bd3832f82c27f96ea2df892088b5b63fa81 Mon Sep 17 00:00:00 2001
From: Brian Ben Maranville <brian.maranville@nist.gov>
Date: Thu, 18 Feb 2021 14:32:53 -0500
Subject: [PATCH] fixing read errors on object headers v2 - was not tracking
 continuation blocks properly, or skipping the signature on the continuation
 blocks

---
 esm/dataobjects.js | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/esm/dataobjects.js b/esm/dataobjects.js
index 8566097..9ce4292 100644
--- a/esm/dataobjects.js
+++ b/esm/dataobjects.js
@@ -353,6 +353,8 @@ export class DataObjects {
 
   _parse_v2_objects(buf, offset) {
     /* Parse a collection of version 2 Data Objects. */
+    // NOTE: this is using absolute address even for messages in continuation 
+    // blocks, and not keeping a concatenated message block (unlike pyfive)
 
     var [header, creation_order_size, block_offset] = this._parse_v2_header(buf, offset);
     offset = block_offset;
@@ -365,7 +367,7 @@ export class DataObjects {
     var local_offset = 0;
 
     while (true) {
-      if (local_offset >= block_size) {
+      if (local_offset >= block_size - HEADER_MSG_INFO_V2_SIZE) {
         let next_block = object_header_blocks[++current_block];
         if (next_block == null) {
           break
@@ -378,7 +380,8 @@ export class DataObjects {
       msg.set('offset_to_message', offset_to_message);
       if (msg.get('type') == OBJECT_CONTINUATION_MSG_TYPE) {
         var [fh_off, size] = struct.unpack_from('<QQ', buf, offset_to_message);
-        object_header_blocks.push([fh_off, size]);
+        // skip the "OFHC" signature in v2 continuation objects:
+        object_header_blocks.push([fh_off+4, size-4]);
       }
       local_offset += HEADER_MSG_INFO_V2_SIZE + msg.get('size') + creation_order_size;
       msgs.push(msg);