From c44350269a60c941203431170df0262f421ff52a Mon Sep 17 00:00:00 2001
From: Patrick Wuttke <mewin@mewin.de>
Date: Sun, 26 Nov 2023 11:49:23 +0100
Subject: [PATCH] Added code to capture stacktrace whenever an exception is
 thrown.

---
 source/mijin/debug/stacktrace.cpp | 42 ++++++++++++++++++++++++++++++-
 source/mijin/debug/stacktrace.hpp |  1 +
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/source/mijin/debug/stacktrace.cpp b/source/mijin/debug/stacktrace.cpp
index 3936caf..dfca406 100644
--- a/source/mijin/debug/stacktrace.cpp
+++ b/source/mijin/debug/stacktrace.cpp
@@ -1,10 +1,10 @@
 
 #include "./stacktrace.hpp"
 
-#include <cstdint>
 #include <optional>
 #include <string>
 #include <backtrace.h>
+#include "../detect.hpp"
 
 namespace mijin
 {
@@ -32,6 +32,8 @@ struct BacktraceData
 // internal variables
 //
 
+thread_local Optional<Stacktrace> gCurrentExceptionStackTrace;
+
 //
 // internal functions
 //
@@ -85,4 +87,42 @@ Result<Stacktrace> captureStacktrace(unsigned skipFrames) noexcept
     return Stacktrace(std::move(btData.stackframes));
 }
 
+const Optional<Stacktrace>& getExceptionStacktrace() noexcept
+{
+    return gCurrentExceptionStackTrace;
+}
 } // namespace mijin
+
+#if MIJIN_STDLIB == MIJIN_STDLIB_GLIBC
+#include <dlfcn.h>
+
+namespace
+{
+using cxa_throw_type = void (*)(void*, std::type_info*, void(*)(void*));
+using cxa_rethrow_type = void (*)();
+
+cxa_throw_type orig_cxa_throw = nullptr; // Address of the original __cxa_throw
+// cxa_rethrow_type orig_cxa_rethrow = nullptr; // Address of the original __cxa_rethrow
+
+extern "C" void __cxa_throw(void* thrown_exception, std::type_info* tinfo, void (*dest)(void*))
+{
+    if (!orig_cxa_throw) {
+        orig_cxa_throw = reinterpret_cast<cxa_throw_type>(dlsym(RTLD_NEXT, "__cxa_throw"));
+    }
+    if (mijin::Result<mijin::Stacktrace> stacktrace = mijin::captureStacktrace(); stacktrace.isSuccess())
+    {
+        mijin::gCurrentExceptionStackTrace = std::move(*stacktrace);
+    }
+    else
+    {
+        mijin::gCurrentExceptionStackTrace.reset();
+    }
+    if (orig_cxa_throw) {
+        orig_cxa_throw(thrown_exception, tinfo, dest);
+    }
+    else {
+        std::abort();
+    }
+}
+}
+#endif
diff --git a/source/mijin/debug/stacktrace.hpp b/source/mijin/debug/stacktrace.hpp
index d039337..569734f 100644
--- a/source/mijin/debug/stacktrace.hpp
+++ b/source/mijin/debug/stacktrace.hpp
@@ -58,6 +58,7 @@ public:
 //
 
 [[nodiscard]] Result<Stacktrace> captureStacktrace(unsigned skipFrames = 0) noexcept;
+[[nodiscard]] const Optional<Stacktrace>& getExceptionStacktrace() noexcept;
 
 template<typename TStream>
 TStream& operator<<(TStream& stream, const Stackframe& stackframe)