From 9531ebd65af362c7b4c5970080cd6b16812da741 Mon Sep 17 00:00:00 2001
From: Timo Paulssen <timonator@perpetuum-immobile.de>
Date: Tue, 21 Jul 2026 01:46:31 +0200
Subject: [PATCH] "when-end" command that gives the last event number of the
 recording

---
 src/DebuggerExtensionCommand.cc | 15 +++++++++++++++
 src/test/when.py                | 27 +++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/src/DebuggerExtensionCommand.cc b/src/DebuggerExtensionCommand.cc
index 869d326ef3e..fa6ef1b03a0 100644
--- a/src/DebuggerExtensionCommand.cc
+++ b/src/DebuggerExtensionCommand.cc
@@ -80,6 +80,21 @@ static SimpleDebuggerExtensionCommand info_recording(
       return string("Path of recording: \"") + json_escape(trace_dir) + string("\"");
     });
 
+static SimpleDebuggerExtensionCommand when_end(
+    "when-end", "Print the number of the last rr event in the recording.",
+    [](GdbServer&, Task* t, const vector<string>&) {
+      auto task = static_cast<ReplayTask*>(t);
+      auto seek_reader(task->session().as_replay()->trace_reader());
+      FrameTime time;
+      for (;;) {
+        auto result = seek_reader.read_task_event(&time);
+        if (result.type() == TraceTaskEvent::Type::NONE) {
+          break;
+        }
+      }
+      return string("Event at end of recording: ") + to_string(time);
+    });
+
 static std::vector<ReplayTimeline::Mark> back_stack;
 static ReplayTimeline::Mark current_history_cp;
 static std::vector<ReplayTimeline::Mark> forward_stack;
diff --git a/src/test/when.py b/src/test/when.py
index e37b6fd71be..47a47e234ec 100644
--- a/src/test/when.py
+++ b/src/test/when.py
@@ -1,6 +1,11 @@
 from util import *
 import re
 
+send_custom_command('when-end')
+expect_debugger(re.compile(r'Event at end of recording: (\d+)'))
+first_when_end_result = int(last_match().group(1))
+# Check this value after running the program for a bit.
+
 send_custom_command('when')
 expect_debugger(re.compile(r'Completed event: (\d+)'))
 t = int(last_match().group(1))
@@ -43,6 +48,10 @@
 if tid2 != tid:
     failed('ERROR ... tid changed')
 
+send_custom_command('when-end')
+expect_debugger(re.compile(r'Event at end of recording: (\d+)'))
+second_when_end_result = int(last_match().group(1))
+
 # Ensure 'when' terminates a diversion
 expect_expression('(int)strlen("abcd")', 4)
 send_custom_command('when')
@@ -65,4 +74,22 @@
 if tid3 != tid2:
     failed('ERROR ... diversion changed tid')
 
+stepi()
+
+send_custom_command('when-end')
+expect_debugger(re.compile(r'Event at end of recording: (\d+)'))
+final_when_end_result = int(last_match().group(1))
+
+if first_when_end_result != second_when_end_result:
+    failed("ERROR ... first when-end result differs from second when-end result")
+if second_when_end_result != final_when_end_result:
+    failed("ERROR ... second when-end result differs from final when-end result")
+
+if t >= first_when_end_result:
+    failed("ERROR ... First when result was after when-end")
+if t3 >= first_when_end_result:
+    failed("ERROR ... Second when result was after when-end")
+if t3 >= first_when_end_result:
+    failed("ERROR ... Third when result was after when-end")
+
 ok()