src: expose ListNode<T>::prev_ on postmortem metadata

Make ListNode<T> postmortem easier to find last items in the queue.

PR-URL: https://github.com/nodejs/node/pull/30027
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

2 files changed, 24 insertions, 15 deletions

diff --git a/src/node_postmortem_metadata.cc b/src/node_postmortem_metadata.cc
index 05800f79b0..ccb347e951 100644
--- a/src/node_postmortem_metadata.cc
+++ b/src/node_postmortem_metadata.cc
@@ -27,9 +27,11 @@
     HandleWrap::handle_wrap_queue_)                                           \
   V(Environment_HandleWrapQueue, head_, ListNode_HandleWrap,                  \
     Environment::HandleWrapQueue::head_)                                      \
+  V(ListNode_HandleWrap, prev_, uintptr_t, ListNode<HandleWrap>::prev_)       \
   V(ListNode_HandleWrap, next_, uintptr_t, ListNode<HandleWrap>::next_)       \
   V(Environment_ReqWrapQueue, head_, ListNode_ReqWrapQueue,                   \
     Environment::ReqWrapQueue::head_)                                         \
+  V(ListNode_ReqWrap, prev_, uintptr_t, ListNode<ReqWrapBase>::prev_)         \
   V(ListNode_ReqWrap, next_, uintptr_t, ListNode<ReqWrapBase>::next_)
 
 extern "C" {
diff --git a/test/cctest/test_node_postmortem_metadata.cc b/test/cctest/test_node_postmortem_metadata.cc
index 79b766939b..f33d40eb5c 100644
--- a/test/cctest/test_node_postmortem_metadata.cc
+++ b/test/cctest/test_node_postmortem_metadata.cc
@@ -19,8 +19,10 @@ extern uintptr_t
 extern uintptr_t
     nodedbg_offset_Environment__req_wrap_queue___Environment_ReqWrapQueue;
 extern uintptr_t nodedbg_offset_ExternalString__data__uintptr_t;
+extern uintptr_t nodedbg_offset_ListNode_ReqWrap__prev___uintptr_t;
 extern uintptr_t nodedbg_offset_ListNode_ReqWrap__next___uintptr_t;
 extern uintptr_t nodedbg_offset_ReqWrap__req_wrap_queue___ListNode_ReqWrapQueue;
+extern uintptr_t nodedbg_offset_ListNode_HandleWrap__prev___uintptr_t;
 extern uintptr_t nodedbg_offset_ListNode_HandleWrap__next___uintptr_t;
 extern uintptr_t
     nodedbg_offset_Environment_ReqWrapQueue__head___ListNode_ReqWrapQueue;
@@ -129,6 +131,12 @@ TEST_F(DebugSymbolsTest, HandleWrapList) {
   const Argv argv;
   Env env{handle_scope, argv};
 
+  auto queue = reinterpret_cast<uintptr_t>((*env)->handle_wrap_queue());
+  auto head = queue +
+      nodedbg_offset_Environment_HandleWrapQueue__head___ListNode_HandleWrap;
+  auto tail = head + nodedbg_offset_ListNode_HandleWrap__prev___uintptr_t;
+  tail = *reinterpret_cast<uintptr_t*>(tail);
+
   uv_tcp_t handle;
 
   auto obj_template = v8::FunctionTemplate::New(isolate_);
@@ -140,16 +148,12 @@ TEST_F(DebugSymbolsTest, HandleWrapList) {
                                      .ToLocalChecked();
   TestHandleWrap obj(*env, object, &handle);
 
-  auto queue = reinterpret_cast<uintptr_t>((*env)->handle_wrap_queue());
-  auto head = queue +
-      nodedbg_offset_Environment_HandleWrapQueue__head___ListNode_HandleWrap;
-  auto next =
-      head + nodedbg_offset_ListNode_HandleWrap__next___uintptr_t;
-  next = *reinterpret_cast<uintptr_t*>(next);
+  auto last = tail + nodedbg_offset_ListNode_HandleWrap__next___uintptr_t;
+  last = *reinterpret_cast<uintptr_t*>(last);
 
   auto expected = reinterpret_cast<uintptr_t>(&obj);
-  auto calculated = next -
-      nodedbg_offset_HandleWrap__handle_wrap_queue___ListNode_HandleWrap;
+  auto calculated =
+      last - nodedbg_offset_HandleWrap__handle_wrap_queue___ListNode_HandleWrap;
   EXPECT_EQ(expected, calculated);
 
   obj.persistent().Reset();  // ~HandleWrap() expects an empty handle.
@@ -160,6 +164,13 @@ TEST_F(DebugSymbolsTest, ReqWrapList) {
   const Argv argv;
   Env env{handle_scope, argv};
 
+  auto queue = reinterpret_cast<uintptr_t>((*env)->req_wrap_queue());
+  auto head =
+      queue +
+      nodedbg_offset_Environment_ReqWrapQueue__head___ListNode_ReqWrapQueue;
+  auto tail = head + nodedbg_offset_ListNode_ReqWrap__prev___uintptr_t;
+  tail = *reinterpret_cast<uintptr_t*>(tail);
+
   auto obj_template = v8::FunctionTemplate::New(isolate_);
   obj_template->InstanceTemplate()->SetInternalFieldCount(1);
 
@@ -174,16 +185,12 @@ TEST_F(DebugSymbolsTest, ReqWrapList) {
   // ARM64 CI machinies.
   for (auto it : *(*env)->req_wrap_queue()) (void) &it;
 
-  auto queue = reinterpret_cast<uintptr_t>((*env)->req_wrap_queue());
-  auto head = queue +
-      nodedbg_offset_Environment_ReqWrapQueue__head___ListNode_ReqWrapQueue;
-  auto next =
-      head + nodedbg_offset_ListNode_ReqWrap__next___uintptr_t;
-  next = *reinterpret_cast<uintptr_t*>(next);
+  auto last = tail + nodedbg_offset_ListNode_ReqWrap__next___uintptr_t;
+  last = *reinterpret_cast<uintptr_t*>(last);
 
   auto expected = reinterpret_cast<uintptr_t>(&obj);
   auto calculated =
-      next - nodedbg_offset_ReqWrap__req_wrap_queue___ListNode_ReqWrapQueue;
+      last - nodedbg_offset_ReqWrap__req_wrap_queue___ListNode_ReqWrapQueue;
   EXPECT_EQ(expected, calculated);
 
   obj.Dispatched();