From c8d9c099b78f5771a0faa420828be4e574040736 Mon Sep 17 00:00:00 2001
From: Alexander Motzkau <a.motzkau@web.de>
Date: Tue, 14 Feb 2023 22:24:25 +0100
Subject: [PATCH] Fix crash (bad stack) when calling coroutines with
 efun::trace()

When efun::trace() is active, the stack pointer was modified in a wrong
way when executing a yield() statement.
---
 src/interpret.c          |  4 ++-
 test/t-trace-coroutine.c | 60 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 test/t-trace-coroutine.c

diff --git a/src/interpret.c b/src/interpret.c
index a2f9f50a..cd0c2c8a 100644
--- a/src/interpret.c
+++ b/src/interpret.c
@@ -10042,6 +10042,8 @@ eval_instruction (bytecode_p first_instruction
         sp = restore_argument_frames(sp-1, &ap)+1;
         if (sp < inter_sp)
             *sp = *inter_sp;
+
+        tracedepth++;
     }
     SET_TRACE_EXEC();
 
@@ -11389,7 +11391,7 @@ again:
 
         tracedepth--; /* We leave this level */
         if (trace_level)
-            do_trace_return(sp);
+            do_trace_return(inter_sp);
 
         pop_control_stack();
 
diff --git a/test/t-trace-coroutine.c b/test/t-trace-coroutine.c
new file mode 100644
index 00000000..2fd09d16
--- /dev/null
+++ b/test/t-trace-coroutine.c
@@ -0,0 +1,60 @@
+#include "/inc/base.inc"
+#include "/inc/client.inc"
+
+#include "/sys/trace.h"
+
+/* We test calling coroutines while efun::trace() is active. */
+
+void run_server()
+{
+    efun::trace(TRACE_CALL_OTHER|TRACE_RETURN|TRACE_ARGS);
+
+    coroutine cr = async function void()
+    {
+        yield("A");
+        yield("B");
+        yield("C");
+    };
+
+    foreach(string str: cr)
+        if (!stringp(str))
+        {
+            efun::shutdown(1);
+            return;
+        }
+
+    efun::trace(TRACE_NOTHING);
+
+    /* The test succeeds, if we didn't crash. */
+    call_out(#'efun::shutdown,0,0);
+}
+
+void run_client()
+{
+    input_to("client_input");
+}
+
+void client_input(string str)
+{
+    input_to("client_input");
+}
+
+void run_test()
+{
+    msg("\nRunning test for tracing with coroutines:\n"
+          "-----------------------------------------\n");
+
+    /* For efun::trace() we need an interactive object. */
+    connect_self("run_server", "run_client");
+}
+
+string *epilog(int eflag)
+{
+    run_test();
+    return 0;
+}
+
+int valid_trace(string what, int|string arg)
+{
+    return 1;
+}